Add cpp23

Add function for property sizes

.clang-format

@@ -2,7 +2,7 @@
 BasedOnStyle: Google
 ---
 Language:     Cpp
-Standard:     "c++20"
+Standard:     c++20
 UseTab:       Never
 DerivePointerAlignment: false
 PointerAlignment: Right

.clang-tidy

@@ -6,6 +6,7 @@ Checks: '*,
          -altera-unroll-loops,
          -android-*,
          -cert-err58-cpp,
+         -cppcoreguidelines-avoid-do-while,
          -cppcoreguidelines-avoid-c-arrays,
          -cppcoreguidelines-avoid-goto,
          -cppcoreguidelines-avoid-magic-numbers,
@@ -60,6 +61,7 @@ Checks: '*,
          -readability-implicit-bool-conversion,
          -readability-magic-numbers,
          -readability-named-parameter,
+         -readability-identifier-length,
          -misc-no-recursion,
          -concurrency-mt-unsafe,
          -bugprone-easily-swappable-parameters'

.github/ISSUE_TEMPLATE/bug_report.md

@@ -3,7 +3,6 @@ name: Bug report
 about: Create a report to help us improve
 title: ""
 labels: bug
-assignees: gitbuda
 ---
 
 **Memgraph version**

.github/workflows/daily_benchmark.yaml

@@ -16,7 +16,7 @@ jobs:
 
     steps:
       - name: Set up repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Number of commits to fetch. `0` indicates all history for all
           # branches and tags. (default: 1)

.github/workflows/diff.yaml

@@ -27,7 +27,7 @@ jobs:
 
     steps:
       - name: Set up repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Number of commits to fetch. `0` indicates all history for all
           # branches and tags. (default: 1)
@@ -65,7 +65,7 @@ jobs:
 
     steps:
       - name: Set up repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Number of commits to fetch. `0` indicates all history for all
           # branches and tags. (default: 1)
@@ -96,7 +96,7 @@ jobs:
 
       - name: Python code analysis
         run: |
-          CHANGED_FILES=$(git diff -U0 ${{ env.BASE_BRANCH }}... --name-only)
+          CHANGED_FILES=$(git diff -U0 ${{ env.BASE_BRANCH }}... --name-only --diff-filter=d)
           for file in ${CHANGED_FILES}; do
             echo ${file}
             if [[ ${file} == *.py ]]; then
@@ -137,9 +137,9 @@ jobs:
           tar -czf code_coverage.tar.gz coverage.json html report.json summary.rmu
 
       - name: Save code coverage
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
-          name: "Code coverage"
+          name: "Code coverage(Code analysis)"
           path: tools/github/generated/code_coverage.tar.gz
 
       - name: Run clang-tidy
@@ -162,7 +162,7 @@ jobs:
 
     steps:
       - name: Set up repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Number of commits to fetch. `0` indicates all history for all
           # branches and tags. (default: 1)
@@ -208,9 +208,9 @@ jobs:
           ./cppcheck_and_clang_format diff
 
       - name: Save cppcheck and clang-format errors
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
-          name: "Code coverage"
+          name: "Code coverage(Debug build)"
           path: tools/github/cppcheck_and_clang_format.txt
 
   release_build:
@@ -223,7 +223,7 @@ jobs:
 
     steps:
       - name: Set up repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Number of commits to fetch. `0` indicates all history for all
           # branches and tags. (default: 1)
@@ -251,7 +251,7 @@ jobs:
           ./continuous_integration
 
       - name: Save quality assurance status
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: "GQL Behave Status"
           path: |
@@ -283,7 +283,6 @@ jobs:
           ./run.sh
 
       - name: Ensure Kafka and Pulsar are down
-        if: always()
         run: |
           cd tests/e2e/streams/kafka
           docker-compose down
@@ -323,16 +322,16 @@ jobs:
           cpack -G DEB --config ../CPackConfig.cmake
 
       - name: Save enterprise DEB package
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: "Enterprise DEB package"
           path: build/output/memgraph*.deb
 
       - name: Save test data
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         if: always()
         with:
-          name: "Test data"
+          name: "Test data(Release build)"
           path: |
             # multiple paths could be defined
             build/logs
@@ -347,7 +346,7 @@ jobs:
 
     steps:
       - name: Set up repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Number of commits to fetch. `0` indicates all history for all
           # branches and tags. (default: 1)
@@ -366,6 +365,7 @@ jobs:
           cd build
           ctest -R memgraph__unit --output-on-failure -j$THREADS
       - name: Run e2e tests
+        if: false
         run: |
           cd tests
           ./setup.sh /opt/toolchain-v4/activate
@@ -375,74 +375,10 @@ jobs:
           ./run.sh "Client initiated failover"
           ./run.sh "Uninitialized cluster"
       - name: Save test data
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         if: always()
         with:
-          name: "Test data"
-          path: |
-            # multiple paths could be defined
-            build/logs
-
-  experimental_build_mt:
-    name: "MultiTenancy replication build"
-    runs-on: [self-hosted, Linux, X64, Diff]
-    env:
-      THREADS: 24
-      MEMGRAPH_ENTERPRISE_LICENSE: ${{ secrets.MEMGRAPH_ENTERPRISE_LICENSE }}
-      MEMGRAPH_ORGANIZATION_NAME: ${{ secrets.MEMGRAPH_ORGANIZATION_NAME }}
-
-    steps:
-      - name: Set up repository
-        uses: actions/checkout@v3
-        with:
-          # Number of commits to fetch. `0` indicates all history for all
-          # branches and tags. (default: 1)
-          fetch-depth: 0
-
-
-      - name: Build release binaries
-        run: |
-          # Activate toolchain.
-          source /opt/toolchain-v4/activate
-
-          # Initialize dependencies.
-          ./init
-
-          # Build MT replication experimental binaries.
-          cd build
-          cmake -DCMAKE_BUILD_TYPE=Release -D MG_EXPERIMENTAL_REPLICATION_MULTITENANCY=ON ..
-          make -j$THREADS
-
-      - name: Run unit tests
-        run: |
-          # Activate toolchain.
-          source /opt/toolchain-v4/activate
-
-          # Run unit tests.
-          cd build
-          ctest -R memgraph__unit --output-on-failure -j$THREADS
-
-      - name: Run e2e tests
-        run: |
-          cd tests
-          ./setup.sh /opt/toolchain-v4/activate
-          source ve3/bin/activate_e2e
-          cd e2e
-
-          # Just the replication based e2e tests
-          ./run.sh "Replicate multitenancy"
-          ./run.sh "Show"
-          ./run.sh "Show while creating invalid state"
-          ./run.sh "Delete edge replication"
-          ./run.sh "Read-write benchmark"
-          ./run.sh "Index replication"
-          ./run.sh "Constraints"
-
-      - name: Save test data
-        uses: actions/upload-artifact@v3
-        if: always()
-        with:
-          name: "Test data"
+          name: "Test data(High availability build)"
           path: |
             # multiple paths could be defined
             build/logs
@@ -458,7 +394,7 @@ jobs:
 
     steps:
       - name: Set up repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Number of commits to fetch. `0` indicates all history for all
           # branches and tags. (default: 1)
@@ -475,13 +411,18 @@ jobs:
           cmake -DCMAKE_BUILD_TYPE=RelWithDebInfo ..
           make -j$THREADS memgraph
 
+      - name: Refresh Jepsen Cluster
+        run: |
+          cd tests/jepsen
+          ./run.sh cluster-refresh
+
       - name: Run Jepsen tests
         run: |
           cd tests/jepsen
           ./run.sh test-all-individually --binary ../../build/memgraph --ignore-run-stdout-logs --ignore-run-stderr-logs
 
       - name: Save Jepsen report
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         if: ${{ always() }}
         with:
           name: "Jepsen Report"
@@ -497,7 +438,7 @@ jobs:
 
     steps:
       - name: Set up repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Number of commits to fetch. `0` indicates all history for all
           # branches and tags. (default: 1)

.github/workflows/full_clang_tidy.yaml

@@ -14,7 +14,7 @@ jobs:
 
     steps:
       - name: Set up repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Number of commits to fetch. `0` indicates all history for all
           # branches and tags. (default: 1)

.github/workflows/package_memgraph.yaml

@@ -42,14 +42,14 @@ jobs:
     timeout-minutes: 60
     steps:
       - name: "Set up repository"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0 # Required because of release/get_version.py
       - name: "Build package"
         run: |
           ./release/package/run.sh package amzn-2 ${{ github.event.inputs.build_type }}
       - name: "Upload package"
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: amzn-2
           path: build/output/amzn-2/memgraph*.rpm
@@ -60,14 +60,14 @@ jobs:
     timeout-minutes: 60
     steps:
       - name: "Set up repository"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0 # Required because of release/get_version.py
       - name: "Build package"
         run: |
           ./release/package/run.sh package centos-7 ${{ github.event.inputs.build_type }}
       - name: "Upload package"
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: centos-7
           path: build/output/centos-7/memgraph*.rpm
@@ -78,14 +78,14 @@ jobs:
     timeout-minutes: 60
     steps:
       - name: "Set up repository"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0 # Required because of release/get_version.py
       - name: "Build package"
         run: |
           ./release/package/run.sh package centos-9 ${{ github.event.inputs.build_type }}
       - name: "Upload package"
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: centos-9
           path: build/output/centos-9/memgraph*.rpm
@@ -96,14 +96,14 @@ jobs:
     timeout-minutes: 60
     steps:
       - name: "Set up repository"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0 # Required because of release/get_version.py
       - name: "Build package"
         run: |
           ./release/package/run.sh package debian-10 ${{ github.event.inputs.build_type }}
       - name: "Upload package"
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: debian-10
           path: build/output/debian-10/memgraph*.deb
@@ -114,14 +114,14 @@ jobs:
     timeout-minutes: 60
     steps:
       - name: "Set up repository"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0 # Required because of release/get_version.py
       - name: "Build package"
         run: |
           ./release/package/run.sh package debian-11 ${{ github.event.inputs.build_type }}
       - name: "Upload package"
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: debian-11
           path: build/output/debian-11/memgraph*.deb
@@ -132,14 +132,14 @@ jobs:
     timeout-minutes: 120
     steps:
       - name: "Set up repository"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0 # Required because of release/get_version.py
       - name: "Build package"
         run: |
           ./release/package/run.sh package debian-11-arm ${{ github.event.inputs.build_type }}
       - name: "Upload package"
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: debian-11-aarch64
           path: build/output/debian-11-arm/memgraph*.deb
@@ -150,14 +150,14 @@ jobs:
     timeout-minutes: 60
     steps:
       - name: "Set up repository"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0 # Required because of release/get_version.py
       - name: "Build package"
         run: |
           ./release/package/run.sh package debian-11 ${{ github.event.inputs.build_type }} --for-platform
       - name: "Upload package"
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: debian-11-platform
           path: build/output/debian-11/memgraph*.deb
@@ -168,7 +168,7 @@ jobs:
     timeout-minutes: 60
     steps:
       - name: "Set up repository"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0 # Required because of release/get_version.py
       - name: "Build package"
@@ -177,7 +177,7 @@ jobs:
           ./run.sh package debian-11 ${{ github.event.inputs.build_type }} --for-docker
           ./run.sh docker
       - name: "Upload package"
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: docker
           path: build/output/docker/memgraph*.tar.gz
@@ -188,14 +188,14 @@ jobs:
     timeout-minutes: 60
     steps:
       - name: "Set up repository"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0 # Required because of release/get_version.py
       - name: "Build package"
         run: |
           ./release/package/run.sh package fedora-36 ${{ github.event.inputs.build_type }}
       - name: "Upload package"
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: fedora-36
           path: build/output/fedora-36/memgraph*.rpm
@@ -206,14 +206,14 @@ jobs:
     timeout-minutes: 60
     steps:
       - name: "Set up repository"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0 # Required because of release/get_version.py
       - name: "Build package"
         run: |
           ./release/package/run.sh package ubuntu-18.04 ${{ github.event.inputs.build_type }}
       - name: "Upload package"
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: ubuntu-18.04
           path: build/output/ubuntu-18.04/memgraph*.deb
@@ -224,14 +224,14 @@ jobs:
     timeout-minutes: 60
     steps:
       - name: "Set up repository"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0 # Required because of release/get_version.py
       - name: "Build package"
         run: |
           ./release/package/run.sh package ubuntu-20.04 ${{ github.event.inputs.build_type }}
       - name: "Upload package"
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: ubuntu-20.04
           path: build/output/ubuntu-20.04/memgraph*.deb
@@ -242,14 +242,14 @@ jobs:
     timeout-minutes: 60
     steps:
       - name: "Set up repository"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0 # Required because of release/get_version.py
       - name: "Build package"
         run: |
           ./release/package/run.sh package ubuntu-22.04 ${{ github.event.inputs.build_type }}
       - name: "Upload package"
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: ubuntu-22.04
           path: build/output/ubuntu-22.04/memgraph*.deb
@@ -260,14 +260,14 @@ jobs:
     timeout-minutes: 120
     steps:
       - name: "Set up repository"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0 # Required because of release/get_version.py
       - name: "Build package"
         run: |
           ./release/package/run.sh package ubuntu-22.04-arm ${{ github.event.inputs.build_type }}
       - name: "Upload package"
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: ubuntu-22.04-aarch64
           path: build/output/ubuntu-22.04-arm/memgraph*.deb
@@ -279,7 +279,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Download artifacts
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           # name: # if name input parameter is not provided, all artifacts are downloaded
                   # and put in directories named after each one.

.github/workflows/performance_benchmarks.yaml

@@ -14,7 +14,7 @@ jobs:
 
     steps:
       - name: Set up repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Number of commits to fetch. `0` indicates all history for all
           # branches and tags. (default: 1)

.github/workflows/release_debian10.yaml

@@ -1,4 +1,7 @@
 name: Release Debian 10
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref_name }}
+  cancel-in-progress: true
 
 on:
   workflow_dispatch:
@@ -10,23 +13,30 @@ on:
         options:
           - Release
           - RelWithDebInfo
-
+  push:
+    branches:
+      - "release/**"
+    tags:
+      - "v*.*.*-rc*"
+      - "v*.*-rc*"
   schedule:
     - cron: "0 22 * * *"
 
+env:
+  THREADS: 24
+  MEMGRAPH_ENTERPRISE_LICENSE: ${{ secrets.MEMGRAPH_ENTERPRISE_LICENSE }}
+  MEMGRAPH_ORGANIZATION_NAME: ${{ secrets.MEMGRAPH_ORGANIZATION_NAME }}
+  BUILD_TYPE: ${{ github.event.inputs.build_type || 'Release' }}
+
 jobs:
   community_build:
     name: "Community build"
     runs-on: [self-hosted, Linux, X64, Debian10]
-    env:
-      THREADS: 24
-      MEMGRAPH_ENTERPRISE_LICENSE: ${{ secrets.MEMGRAPH_ENTERPRISE_LICENSE }}
-      MEMGRAPH_ORGANIZATION_NAME: ${{ secrets.MEMGRAPH_ORGANIZATION_NAME }}
-    timeout-minutes: 960
+    timeout-minutes: 60
 
     steps:
       - name: Set up repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Number of commits to fetch. `0` indicates all history for all
           # branches and tags. (default: 1)
@@ -40,10 +50,6 @@ jobs:
           # Initialize dependencies.
           ./init
 
-          # Set default build_type to Release
-          INPUT_BUILD_TYPE=${{ github.event.inputs.build_type }}
-          BUILD_TYPE=${INPUT_BUILD_TYPE:-"Release"}
-
           # Build community binaries.
           cd build
           cmake -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DMG_ENTERPRISE=OFF ..
@@ -65,10 +71,11 @@ jobs:
       THREADS: 24
       MEMGRAPH_ENTERPRISE_LICENSE: ${{ secrets.MEMGRAPH_ENTERPRISE_LICENSE }}
       MEMGRAPH_ORGANIZATION_NAME: ${{ secrets.MEMGRAPH_ORGANIZATION_NAME }}
+    timeout-minutes: 60
 
     steps:
       - name: Set up repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Number of commits to fetch. `0` indicates all history for all
           # branches and tags. (default: 1)
@@ -110,22 +117,19 @@ jobs:
           tar -czf code_coverage.tar.gz coverage.json html report.json summary.rmu
 
       - name: Save code coverage
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
-          name: "Code coverage"
+          name: "Code coverage(Coverage build)"
           path: tools/github/generated/code_coverage.tar.gz
 
   debug_build:
     name: "Debug build"
     runs-on: [self-hosted, Linux, X64, Debian10]
-    env:
-      THREADS: 24
-      MEMGRAPH_ENTERPRISE_LICENSE: ${{ secrets.MEMGRAPH_ENTERPRISE_LICENSE }}
-      MEMGRAPH_ORGANIZATION_NAME: ${{ secrets.MEMGRAPH_ORGANIZATION_NAME }}
+    timeout-minutes: 60
 
     steps:
       - name: Set up repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Number of commits to fetch. `0` indicates all history for all
           # branches and tags. (default: 1)
@@ -157,10 +161,6 @@ jobs:
         run: |
           ./tests/drivers/run.sh
 
-      - name: Run integration tests
-        run: |
-          tests/integration/run.sh
-
       - name: Run cppcheck and clang-format
         run: |
           # Activate toolchain.
@@ -171,23 +171,49 @@ jobs:
           ./cppcheck_and_clang_format diff
 
       - name: Save cppcheck and clang-format errors
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
-          name: "Code coverage"
+          name: "Code coverage(Debug build)"
           path: tools/github/cppcheck_and_clang_format.txt
 
-  release_build:
-    name: "Release build"
-    runs-on: [self-hosted, Linux, X64, Debian10, BigMemory]
-    env:
-      THREADS: 24
-      MEMGRAPH_ENTERPRISE_LICENSE: ${{ secrets.MEMGRAPH_ENTERPRISE_LICENSE }}
-      MEMGRAPH_ORGANIZATION_NAME: ${{ secrets.MEMGRAPH_ORGANIZATION_NAME }}
-    timeout-minutes: 960
+  debug_integration_test:
+    name: "Debug integration tests"
+    runs-on: [self-hosted, Linux, X64, Debian10]
+    timeout-minutes: 60
 
     steps:
       - name: Set up repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
+        with:
+          # Number of commits to fetch. `0` indicates all history for all
+          # branches and tags. (default: 1)
+          fetch-depth: 0
+
+      - name: Build debug binaries
+        run: |
+          # Activate toolchain.
+          source /opt/toolchain-v4/activate
+
+          # Initialize dependencies.
+          ./init
+
+          # Build debug binaries.
+          cd build
+          cmake ..
+          make -j$THREADS
+
+      - name: Run integration tests
+        run: |
+          tests/integration/run.sh
+
+  release_build:
+    name: "Release build"
+    runs-on: [self-hosted, Linux, X64, Debian10]
+    timeout-minutes: 60
+
+    steps:
+      - name: Set up repository
+        uses: actions/checkout@v4
         with:
           # Number of commits to fetch. `0` indicates all history for all
           # branches and tags. (default: 1)
@@ -201,10 +227,6 @@ jobs:
           # Initialize dependencies.
           ./init
 
-          # Set default build_type to Release
-          INPUT_BUILD_TYPE=${{ github.event.inputs.build_type }}
-          BUILD_TYPE=${INPUT_BUILD_TYPE:-"Release"}
-
           # Build release binaries.
           cd build
           cmake -DCMAKE_BUILD_TYPE=$BUILD_TYPE ..
@@ -226,11 +248,60 @@ jobs:
           cpack -G DEB --config ../CPackConfig.cmake
 
       - name: Save enterprise DEB package
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: "Enterprise DEB package"
           path: build/output/memgraph*.deb
 
+      - name: Run GQL Behave tests
+        run: |
+          cd tests
+          ./setup.sh /opt/toolchain-v4/activate
+          cd gql_behave
+          ./continuous_integration
+
+      - name: Save quality assurance status
+        uses: actions/upload-artifact@v4
+        with:
+          name: "GQL Behave Status"
+          path: |
+            tests/gql_behave/gql_behave_status.csv
+            tests/gql_behave/gql_behave_status.html
+
+      - name: Run unit tests
+        run: |
+          # Activate toolchain.
+          source /opt/toolchain-v4/activate
+
+          # Run unit tests.
+          cd build
+          ctest -R memgraph__unit --output-on-failure
+
+  release_benchmark_tests:
+    name: "Release Benchmark Tests"
+    runs-on: [self-hosted, Linux, X64, Debian10]
+    timeout-minutes: 60
+
+    steps:
+      - name: Set up repository
+        uses: actions/checkout@v4
+        with:
+          # Number of commits to fetch. `0` indicates all history for all
+          # branches and tags. (default: 1)
+          fetch-depth: 0
+
+      - name: Build release binaries
+        run: |
+          # Activate toolchain.
+          source /opt/toolchain-v4/activate
+          # Initialize dependencies.
+          ./init
+
+          # Build release binaries
+          cd build
+          cmake -DCMAKE_BUILD_TYPE=$BUILD_TYPE ..
+          make -j$THREADS
+
       - name: Run micro benchmark tests
         run: |
           # Activate toolchain.
@@ -257,29 +328,30 @@ jobs:
             --num-database-workers 9 --num-clients-workers 30 \
             --no-strict
 
-      - name: Run GQL Behave tests
-        run: |
-          cd tests
-          ./setup.sh /opt/toolchain-v4/activate
-          cd gql_behave
-          ./continuous_integration
+  release_e2e_test:
+    name: "Release End-to-end Test"
+    runs-on: [self-hosted, Linux, X64, Debian10]
+    timeout-minutes: 60
 
-      - name: Save quality assurance status
-        uses: actions/upload-artifact@v3
+    steps:
+      - name: Set up repository
+        uses: actions/checkout@v4
         with:
-          name: "GQL Behave Status"
-          path: |
-            tests/gql_behave/gql_behave_status.csv
-            tests/gql_behave/gql_behave_status.html
+          # Number of commits to fetch. `0` indicates all history for all
+          # branches and tags. (default: 1)
+          fetch-depth: 0
 
-      - name: Run unit tests
+      - name: Build release binaries
         run: |
           # Activate toolchain.
           source /opt/toolchain-v4/activate
+          # Initialize dependencies.
+          ./init
 
-          # Run unit tests.
+          # Build release binaries
           cd build
-          ctest -R memgraph__unit --output-on-failure
+          cmake -DCMAKE_BUILD_TYPE=$BUILD_TYPE ..
+          make -j$THREADS
 
       - name: Ensure Kafka and Pulsar are up
         run: |
@@ -304,6 +376,32 @@ jobs:
           cd ../pulsar
           docker-compose down
 
+  release_durability_stress_tests:
+    name: "Release durability and stress tests"
+    runs-on: [self-hosted, Linux, X64, Debian10]
+    timeout-minutes: 60
+
+    steps:
+      - name: Set up repository
+        uses: actions/checkout@v4
+        with:
+          # Number of commits to fetch. `0` indicates all history for all
+          # branches and tags. (default: 1)
+          fetch-depth: 0
+
+      - name: Build release binaries
+        run: |
+          # Activate toolchain.
+          source /opt/toolchain-v4/activate
+
+          # Initialize dependencies.
+          ./init
+
+          # Build release binaries.
+          cd build
+          cmake -DCMAKE_BUILD_TYPE=$BUILD_TYPE ..
+          make -j$THREADS
+
       - name: Run stress test (plain)
         run: |
           cd tests/stress
@@ -314,11 +412,6 @@ jobs:
           cd tests/stress
           ./continuous_integration --use-ssl
 
-      - name: Run stress test (large)
-        run: |
-          cd tests/stress
-          ./continuous_integration --large-dataset
-
       - name: Run durability test (plain)
         run: |
           cd tests/stress
@@ -334,15 +427,11 @@ jobs:
   release_jepsen_test:
     name: "Release Jepsen Test"
     runs-on: [self-hosted, Linux, X64, Debian10, JepsenControl]
-    env:
-      THREADS: 24
-      MEMGRAPH_ENTERPRISE_LICENSE: ${{ secrets.MEMGRAPH_ENTERPRISE_LICENSE }}
-      MEMGRAPH_ORGANIZATION_NAME: ${{ secrets.MEMGRAPH_ORGANIZATION_NAME }}
     timeout-minutes: 60
 
     steps:
       - name: Set up repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Number of commits to fetch. `0` indicates all history for all
           # branches and tags. (default: 1)
@@ -355,22 +444,23 @@ jobs:
           # Initialize dependencies.
           ./init
 
-          # Set default build_type to Release
-          INPUT_BUILD_TYPE=${{ github.event.inputs.build_type }}
-          BUILD_TYPE=${INPUT_BUILD_TYPE:-"Release"}
-
           # Build only memgraph release binary.
           cd build
           cmake -DCMAKE_BUILD_TYPE=$BUILD_TYPE ..
           make -j$THREADS memgraph
 
+      - name: Refresh Jepsen Cluster
+        run: |
+          cd tests/jepsen
+          ./run.sh cluster-refresh
+
       - name: Run Jepsen tests
         run: |
           cd tests/jepsen
           ./run.sh test-all-individually --binary ../../build/memgraph --ignore-run-stdout-logs --ignore-run-stderr-logs
 
       - name: Save Jepsen report
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         if: ${{ always() }}
         with:
           name: "Jepsen Report"

.github/workflows/release_docker.yaml

@@ -19,7 +19,7 @@ jobs:
       DOCKER_REPOSITORY_NAME: memgraph
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v2

.github/workflows/release_mgbench_client.yaml

@@ -20,7 +20,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v2

.github/workflows/release_ubuntu2004.yaml

@@ -1,4 +1,7 @@
 name: Release Ubuntu 20.04
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref_name }}
+  cancel-in-progress: true
 
 on:
   workflow_dispatch:
@@ -10,23 +13,30 @@ on:
         options:
           - Release
           - RelWithDebInfo
-
+  push:
+    branches:
+      - "release/**"
+    tags:
+      - "v*.*.*-rc*"
+      - "v*.*-rc*"
   schedule:
     - cron: "0 22 * * *"
 
+env:
+  THREADS: 24
+  MEMGRAPH_ENTERPRISE_LICENSE: ${{ secrets.MEMGRAPH_ENTERPRISE_LICENSE }}
+  MEMGRAPH_ORGANIZATION_NAME: ${{ secrets.MEMGRAPH_ORGANIZATION_NAME }}
+  BUILD_TYPE: ${{ github.event.inputs.build_type || 'Release' }}
+
 jobs:
   community_build:
     name: "Community build"
     runs-on: [self-hosted, Linux, X64, Ubuntu20.04]
-    env:
-      THREADS: 24
-      MEMGRAPH_ENTERPRISE_LICENSE: ${{ secrets.MEMGRAPH_ENTERPRISE_LICENSE }}
-      MEMGRAPH_ORGANIZATION_NAME: ${{ secrets.MEMGRAPH_ORGANIZATION_NAME }}
-    timeout-minutes: 960
+    timeout-minutes: 60
 
     steps:
       - name: Set up repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Number of commits to fetch. `0` indicates all history for all
           # branches and tags. (default: 1)
@@ -40,10 +50,6 @@ jobs:
           # Initialize dependencies.
           ./init
 
-          # Set default build_type to Release
-          INPUT_BUILD_TYPE=${{ github.event.inputs.build_type }}
-          BUILD_TYPE=${INPUT_BUILD_TYPE:-"Release"}
-
           # Build community binaries.
           cd build
           cmake -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DMG_ENTERPRISE=OFF ..
@@ -61,14 +67,11 @@ jobs:
   coverage_build:
     name: "Coverage build"
     runs-on: [self-hosted, Linux, X64, Ubuntu20.04]
-    env:
-      THREADS: 24
-      MEMGRAPH_ENTERPRISE_LICENSE: ${{ secrets.MEMGRAPH_ENTERPRISE_LICENSE }}
-      MEMGRAPH_ORGANIZATION_NAME: ${{ secrets.MEMGRAPH_ORGANIZATION_NAME }}
+    timeout-minutes: 60
 
     steps:
       - name: Set up repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Number of commits to fetch. `0` indicates all history for all
           # branches and tags. (default: 1)
@@ -110,22 +113,19 @@ jobs:
           tar -czf code_coverage.tar.gz coverage.json html report.json summary.rmu
 
       - name: Save code coverage
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
-          name: "Code coverage"
+          name: "Code coverage(Coverage build)"
           path: tools/github/generated/code_coverage.tar.gz
 
   debug_build:
     name: "Debug build"
     runs-on: [self-hosted, Linux, X64, Ubuntu20.04]
-    env:
-      THREADS: 24
-      MEMGRAPH_ENTERPRISE_LICENSE: ${{ secrets.MEMGRAPH_ENTERPRISE_LICENSE }}
-      MEMGRAPH_ORGANIZATION_NAME: ${{ secrets.MEMGRAPH_ORGANIZATION_NAME }}
+    timeout-minutes: 60
 
     steps:
       - name: Set up repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Number of commits to fetch. `0` indicates all history for all
           # branches and tags. (default: 1)
@@ -157,10 +157,6 @@ jobs:
         run: |
           ./tests/drivers/run.sh
 
-      - name: Run integration tests
-        run: |
-          tests/integration/run.sh
-
       - name: Run cppcheck and clang-format
         run: |
           # Activate toolchain.
@@ -171,23 +167,49 @@ jobs:
           ./cppcheck_and_clang_format diff
 
       - name: Save cppcheck and clang-format errors
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
-          name: "Code coverage"
+          name: "Code coverage(Debug build)"
           path: tools/github/cppcheck_and_clang_format.txt
 
+  debug_integration_test:
+    name: "Debug integration tests"
+    runs-on: [self-hosted, Linux, X64, Ubuntu20.04]
+    timeout-minutes: 60
+
+    steps:
+      - name: Set up repository
+        uses: actions/checkout@v4
+        with:
+          # Number of commits to fetch. `0` indicates all history for all
+          # branches and tags. (default: 1)
+          fetch-depth: 0
+
+      - name: Build debug binaries
+        run: |
+          # Activate toolchain.
+          source /opt/toolchain-v4/activate
+
+          # Initialize dependencies.
+          ./init
+
+          # Build debug binaries.
+          cd build
+          cmake ..
+          make -j$THREADS
+
+      - name: Run integration tests
+        run: |
+          tests/integration/run.sh
+
   release_build:
     name: "Release build"
     runs-on: [self-hosted, Linux, X64, Ubuntu20.04]
-    env:
-      THREADS: 24
-      MEMGRAPH_ENTERPRISE_LICENSE: ${{ secrets.MEMGRAPH_ENTERPRISE_LICENSE }}
-      MEMGRAPH_ORGANIZATION_NAME: ${{ secrets.MEMGRAPH_ORGANIZATION_NAME }}
-    timeout-minutes: 960
+    timeout-minutes: 60
 
     steps:
       - name: Set up repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Number of commits to fetch. `0` indicates all history for all
           # branches and tags. (default: 1)
@@ -201,10 +223,6 @@ jobs:
           # Initialize dependencies.
           ./init
 
-          # Set default build_type to Release
-          INPUT_BUILD_TYPE=${{ github.event.inputs.build_type }}
-          BUILD_TYPE=${INPUT_BUILD_TYPE:-"Release"}
-
           # Build release binaries.
           cd build
           cmake -DCMAKE_BUILD_TYPE=$BUILD_TYPE ..
@@ -226,11 +244,60 @@ jobs:
           cpack -G DEB --config ../CPackConfig.cmake
 
       - name: Save enterprise DEB package
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: "Enterprise DEB package"
           path: build/output/memgraph*.deb
 
+      - name: Run GQL Behave tests
+        run: |
+          cd tests
+          ./setup.sh /opt/toolchain-v4/activate
+          cd gql_behave
+          ./continuous_integration
+
+      - name: Save quality assurance status
+        uses: actions/upload-artifact@v4
+        with:
+          name: "GQL Behave Status"
+          path: |
+            tests/gql_behave/gql_behave_status.csv
+            tests/gql_behave/gql_behave_status.html
+
+      - name: Run unit tests
+        run: |
+          # Activate toolchain.
+          source /opt/toolchain-v4/activate
+
+          # Run unit tests.
+          cd build
+          ctest -R memgraph__unit --output-on-failure
+
+  release_benchmark_tests:
+    name: "Release Benchmark Tests"
+    runs-on: [self-hosted, Linux, X64, Ubuntu20.04]
+    timeout-minutes: 60
+
+    steps:
+      - name: Set up repository
+        uses: actions/checkout@v4
+        with:
+          # Number of commits to fetch. `0` indicates all history for all
+          # branches and tags. (default: 1)
+          fetch-depth: 0
+
+      - name: Build release binaries
+        run: |
+          # Activate toolchain.
+          source /opt/toolchain-v4/activate
+          # Initialize dependencies.
+          ./init
+
+          # Build release binaries
+          cd build
+          cmake -DCMAKE_BUILD_TYPE=$BUILD_TYPE ..
+          make -j$THREADS
+
       - name: Run micro benchmark tests
         run: |
           # Activate toolchain.
@@ -257,29 +324,30 @@ jobs:
             --num-database-workers 9 --num-clients-workers 30 \
             --no-strict
 
-      - name: Run GQL Behave tests
-        run: |
-          cd tests
-          ./setup.sh /opt/toolchain-v4/activate
-          cd gql_behave
-          ./continuous_integration
+  release_e2e_test:
+    name: "Release End-to-end Test"
+    runs-on: [self-hosted, Linux, X64, Ubuntu20.04]
+    timeout-minutes: 60
 
-      - name: Save quality assurance status
-        uses: actions/upload-artifact@v3
+    steps:
+      - name: Set up repository
+        uses: actions/checkout@v4
         with:
-          name: "GQL Behave Status"
-          path: |
-            tests/gql_behave/gql_behave_status.csv
-            tests/gql_behave/gql_behave_status.html
+          # Number of commits to fetch. `0` indicates all history for all
+          # branches and tags. (default: 1)
+          fetch-depth: 0
 
-      - name: Run unit tests
+      - name: Build release binaries
         run: |
           # Activate toolchain.
           source /opt/toolchain-v4/activate
+          # Initialize dependencies.
+          ./init
 
-          # Run unit tests.
+          # Build release binaries
           cd build
-          ctest -R memgraph__unit --output-on-failure
+          cmake -DCMAKE_BUILD_TYPE=$BUILD_TYPE ..
+          make -j$THREADS
 
       - name: Ensure Kafka and Pulsar are up
         run: |
@@ -304,6 +372,32 @@ jobs:
           cd ../pulsar
           docker-compose down
 
+  release_durability_stress_tests:
+    name: "Release durability and stress tests"
+    runs-on: [self-hosted, Linux, X64, Ubuntu20.04]
+    timeout-minutes: 60
+
+    steps:
+      - name: Set up repository
+        uses: actions/checkout@v4
+        with:
+          # Number of commits to fetch. `0` indicates all history for all
+          # branches and tags. (default: 1)
+          fetch-depth: 0
+
+      - name: Build release binaries
+        run: |
+          # Activate toolchain.
+          source /opt/toolchain-v4/activate
+
+          # Initialize dependencies.
+          ./init
+
+          # Build release binaries.
+          cd build
+          cmake -DCMAKE_BUILD_TYPE=$BUILD_TYPE ..
+          make -j$THREADS
+
       - name: Run stress test (plain)
         run: |
           cd tests/stress
@@ -314,11 +408,6 @@ jobs:
           cd tests/stress
           ./continuous_integration --use-ssl
 
-      - name: Run stress test (large)
-        run: |
-          cd tests/stress
-          ./continuous_integration --large-dataset
-
       - name: Run durability test (plain)
         run: |
           cd tests/stress

.github/workflows/stress_test_large.yaml

@@ -0,0 +1,68 @@
+name: Stress test large
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref_name }}
+  cancel-in-progress: true
+
+on:
+  workflow_dispatch:
+    inputs:
+      build_type:
+        type: choice
+        description: "Memgraph Build type. Default value is Release."
+        default: 'Release'
+        options:
+          - Release
+          - RelWithDebInfo
+  push:
+    tags:
+      - "v*.*.*-rc*"
+      - "v*.*-rc*"
+  schedule:
+    - cron: "0 22 * * *"
+
+env:
+  THREADS: 24
+  MEMGRAPH_ENTERPRISE_LICENSE: ${{ secrets.MEMGRAPH_ENTERPRISE_LICENSE }}
+  MEMGRAPH_ORGANIZATION_NAME: ${{ secrets.MEMGRAPH_ORGANIZATION_NAME }}
+  BUILD_TYPE: ${{ github.event.inputs.build_type || 'Release' }}
+
+jobs:
+  stress_test_large:
+    name: "Stress test large"
+    timeout-minutes: 720
+    strategy:
+      matrix:
+        os: [Debian10, Ubuntu20.04]
+        extra: [BigMemory, Gen8]
+        exclude:
+          - os: Debian10
+            extra: Gen8
+          - os: Ubuntu20.04
+            extra: BigMemory
+    runs-on: [self-hosted, Linux, X64, "${{ matrix.os }}", "${{ matrix.extra }}"]
+
+    steps:
+      - name: Set up repository
+        uses: actions/checkout@v4
+        with:
+          # Number of commits to fetch. `0` indicates all history for all
+          # branches and tags. (default: 1)
+          fetch-depth: 0
+
+      - name: Build release binaries
+        run: |
+          # Activate toolchain.
+          source /opt/toolchain-v4/activate
+
+          # Initialize dependencies.
+          ./init
+
+          # Build release binaries.
+          cd build
+          cmake -DCMAKE_BUILD_TYPE=$BUILD_TYPE ..
+          make -j$THREADS
+
+      - name: Run stress test (large)
+        run: |
+          cd tests/stress
+          ./continuous_integration --large-dataset

.github/workflows/upload_to_s3.yaml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Download artifacts
-        uses: dawidd6/action-download-artifact@v2
+        uses: dawidd6/action-download-artifact@v4
         with:
           workflow: package_all.yaml
           workflow_conclusion: success

.pre-commit-config.yaml

@@ -17,9 +17,10 @@ repos:
         name: isort (python)
         args: ["--profile", "black"]
   - repo: https://github.com/pre-commit/mirrors-clang-format
-    rev: v13.0.0
+    rev: v17.0.6
     hooks:
       - id: clang-format
+        types_or: [c++, c]
 #  - repo: local
 #    hooks:
 #      - id: clang-tidy

ADRs/003_rocksdb.md

@@ -0,0 +1,38 @@
+# RocksDB ADR
+
+**Author**
+Marko Budiselic (github.com/gitbuda)
+
+**Status**
+ACCEPTED
+
+**Date**
+January 23, 2024
+
+**Problem**
+
+Interacting with data (reads and writes) on disk in a concurrent, safe, and
+fast way is a challenging task. Implementing all low-level primitives to
+interact with various disk hardware efficiently consumes significant
+engineering people. Whenever Memgraph has to store data on disk (or any
+other colder than RAM storage system), the problem is how to do that in the
+least amount of development time while satisfying all functional requirements
+(often performance).
+
+**Criteria**
+
+- working efficiently in a highly concurrent environment
+- easy integration with Memgraph's C++ codebase
+- providing low-level key-value API
+- heavily tested in production environments
+- providing abstractions for the storage hardware (even for cloud-based
+  storages like S3)
+
+**Decision**
+
+There are a few robust key-value stores, but finding one that is
+production-ready and compatible with Memgraph's C++ codebase is challenging.
+**We select [RocksDB](https://github.com/facebook/rocksdb)** because it
+delivers robust API to manage data on disk; it's battle-tested in many
+production environments (many databases systems are embedding RocksDB), and
+it's the most compatible one.

CMakeLists.txt

@@ -189,7 +189,7 @@ add_custom_target(clean_all
 # is easier debugging of compilation and linker flags.
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
-set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD 23)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 # c99-designator is disabled because of required mixture of designated and
 # non-designated initializers in Python Query Module code (`py_module.cpp`).
@@ -275,7 +275,7 @@ option(MG_EXPERIMENTAL_HIGH_AVAILABILITY "Feature flag for experimental high ava
 
 if (NOT MG_ENTERPRISE AND MG_EXPERIMENTAL_HIGH_AVAILABILITY)
     set(MG_EXPERIMENTAL_HIGH_AVAILABILITY OFF)
-    message(FATAL_ERROR "MG_EXPERIMENTAL_HIGH_AVAILABILITY must be used with enterpise version of the code.")
+    message(FATAL_ERROR "MG_EXPERIMENTAL_HIGH_AVAILABILITY can only be used with enterpise version of the code.")
 endif ()
 
 if (MG_EXPERIMENTAL_HIGH_AVAILABILITY)
@@ -291,16 +291,6 @@ option(TSAN "Build with Thread Sanitizer. To get a reasonable performance option
 option(UBSAN "Build with Undefined Behaviour Sanitizer" OFF)
 
 # Build feature flags
-option(MG_EXPERIMENTAL_REPLICATION_MULTITENANCY "Feature flag for experimental replicaition of multitenacy" OFF)
-
-if (NOT MG_ENTERPRISE AND MG_EXPERIMENTAL_REPLICATION_MULTITENANCY)
-    set(MG_EXPERIMENTAL_REPLICATION_MULTITENANCY OFF)
-    message(FATAL_ERROR "MG_EXPERIMENTAL_REPLICATION_MULTITENANCY with community edition build isn't possible")
-endif ()
-
-if (MG_EXPERIMENTAL_REPLICATION_MULTITENANCY)
-    add_compile_definitions(MG_EXPERIMENTAL_REPLICATION_MULTITENANCY)
-endif ()
 
 if (TEST_COVERAGE)
   string(TOLOWER ${CMAKE_BUILD_TYPE} lower_build_type)

init

@@ -120,7 +120,7 @@ fi
 # develop on them -> pre-commit hook not required -> we can use latest
 # packages.
 if [ "${DISTRO}" != "centos-7" ] && [ "$DISTRO" != "debian-10" ] && [ "${DISTRO}" != "ubuntu-18.04" ] && [ "${DISTRO}" != "amzn-2" ]; then
-  python3 -m pip install pre-commit
+  python3 -m pip install pre-commit==3.5.*
   python3 -m pre_commit install
   # Install py format tools for usage during the development.
   echo "Install black formatter"

libs/CMakeLists.txt

@@ -294,3 +294,10 @@ set_path_external_library(jemalloc STATIC
   ${CMAKE_CURRENT_SOURCE_DIR}/jemalloc/include/)
 
 import_header_library(rangev3 ${CMAKE_CURRENT_SOURCE_DIR}/rangev3/include)
+
+# Setup NuRaft
+import_external_library(nuraft STATIC
+  ${CMAKE_CURRENT_SOURCE_DIR}/nuraft/lib/libnuraft.a
+  ${CMAKE_CURRENT_SOURCE_DIR}/nuraft/include/)
+find_package(OpenSSL REQUIRED)
+target_link_libraries(nuraft INTERFACE ${OPENSSL_LIBRARIES})

libs/setup.sh

@@ -123,9 +123,10 @@ declare -A primary_urls=(
   ["pulsar"]="http://$local_cache_host/git/pulsar.git"
   ["librdtsc"]="http://$local_cache_host/git/librdtsc.git"
   ["ctre"]="http://$local_cache_host/file/hanickadot/compile-time-regular-expressions/v3.7.2/single-header/ctre.hpp"
-  ["absl"]="https://$local_cache_host/git/abseil-cpp.git"
-  ["jemalloc"]="https://$local_cache_host/git/jemalloc.git"
-  ["range-v3"]="https://$local_cache_host/git/ericniebler/range-v3.git"
+  ["absl"]="http://$local_cache_host/git/abseil-cpp.git"
+  ["jemalloc"]="http://$local_cache_host/git/jemalloc.git"
+  ["range-v3"]="http://$local_cache_host/git/range-v3.git"
+  ["nuraft"]="http://$local_cache_host/git/NuRaft.git"
 )
 
 # The goal of secondary urls is to have links to the "source of truth" of
@@ -155,6 +156,7 @@ declare -A secondary_urls=(
   ["absl"]="https://github.com/abseil/abseil-cpp.git"
   ["jemalloc"]="https://github.com/jemalloc/jemalloc.git"
   ["range-v3"]="https://github.com/ericniebler/range-v3.git"
+  ["nuraft"]="https://github.com/eBay/NuRaft.git"
 )
 
 # antlr
@@ -268,6 +270,8 @@ pushd jemalloc
 MALLOC_CONF="retain:false,percpu_arena:percpu,oversize_threshold:0,muzzy_decay_ms:5000,dirty_decay_ms:5000" \
 ./configure \
   --disable-cxx \
+  --with-lg-page=12 \
+  --with-lg-hugepage=21 \
   --enable-shared=no --prefix=$working_dir \
   --with-malloc-conf="retain:false,percpu_arena:percpu,oversize_threshold:0,muzzy_decay_ms:5000,dirty_decay_ms:5000"
 
@@ -277,3 +281,10 @@ popd
 #range-v3 release-0.12.0
 range_v3_ref="release-0.12.0"
 repo_clone_try_double "${primary_urls[range-v3]}" "${secondary_urls[range-v3]}" "rangev3" "$range_v3_ref"
+
+# NuRaft
+nuraft_tag="v2.1.0"
+repo_clone_try_double "${primary_urls[nuraft]}" "${secondary_urls[nuraft]}" "nuraft" "$nuraft_tag" true
+pushd nuraft
+./prepare.sh
+popd

query_modules/mgp_mock_example.py

@@ -1,17 +0,0 @@
-# https://memgraph.com/docs/custom-query-modules/python
-# changes_logger.py OR can be directly pasted into the Lab
-import mgp_mock as mgp
-
-@mgp.read_proc
-def log(
-  context: mgp.ProcCtx,
-  data: mgp.Nullable[mgp.Any]
-) -> mgp.Record(done=bool):
-  # https://memgraph.com/docs/custom-query-modules/python/python-api#logger-objects
-  logger = mgp.Logger()
-  for changes in data:
-    for item in changes:
-      logger.info(str(item))
-  return mgp.Record(done=True)
-
-log(mgp.ProcCtx, ["bla"])

src/CMakeLists.txt

@@ -22,8 +22,10 @@ add_subdirectory(dbms)
 add_subdirectory(flags)
 add_subdirectory(distributed)
 add_subdirectory(replication)
+add_subdirectory(replication_handler)
 add_subdirectory(coordination)
 add_subdirectory(replication_coordination_glue)
+add_subdirectory(system)
 
 string(TOLOWER ${CMAKE_BUILD_TYPE} lower_build_type)
 
@@ -43,10 +45,10 @@ set(mg_single_node_v2_sources
 add_executable(memgraph ${mg_single_node_v2_sources})
 target_include_directories(memgraph PUBLIC ${CMAKE_SOURCE_DIR}/include)
 target_link_libraries(memgraph stdc++fs Threads::Threads
-        mg-telemetry mg-communication mg-communication-metrics mg-memory mg-utils mg-license mg-settings mg-glue mg-flags)
+        mg-telemetry mg-communication mg-communication-metrics mg-memory mg-utils mg-license mg-settings mg-glue mg-flags mg::system mg::replication_handler)
 
 # NOTE: `include/mg_procedure.syms` describes a pattern match for symbols which
-# should be dynamically exported, so that `dlopen` can correctly link the
+# should be dynamically exported, so that `dlopen` can correctly link th
 # symbols in custom procedure module libraries.
 target_link_libraries(memgraph "-Wl,--dynamic-list=${CMAKE_SOURCE_DIR}/include/mg_procedure.syms")
 set_target_properties(memgraph PROPERTIES

src/auth/CMakeLists.txt

@@ -2,7 +2,9 @@ set(auth_src_files
     auth.cpp
     crypto.cpp
     models.cpp
-    module.cpp)
+    module.cpp
+    rpc.cpp
+    replication_handlers.cpp)
 
 find_package(Seccomp REQUIRED)
 find_package(fmt REQUIRED)
@@ -11,7 +13,7 @@ find_package(gflags REQUIRED)
 
 add_library(mg-auth STATIC ${auth_src_files})
 target_link_libraries(mg-auth json libbcrypt gflags fmt::fmt)
-target_link_libraries(mg-auth mg-utils mg-kvstore mg-license )
+target_link_libraries(mg-auth mg-utils mg-kvstore mg-license mg::system mg-replication)
 
 target_link_libraries(mg-auth ${Seccomp_LIBRARIES})
 target_include_directories(mg-auth SYSTEM PRIVATE ${Seccomp_INCLUDE_DIRS})

src/auth/auth.cpp

@@ -1,4 +1,4 @@
-// Copyright 2023 Memgraph Ltd.
+// Copyright 2024 Memgraph Ltd.
 //
 // Licensed as a Memgraph Enterprise file under the Memgraph Enterprise
 // License (the "License"); by using this file, you agree to be bound by the terms of the License, and you may not use
@@ -8,17 +8,18 @@
 
 #include "auth/auth.hpp"
 
-#include <cstring>
 #include <iostream>
-#include <limits>
+#include <optional>
 #include <utility>
 
 #include <fmt/format.h>
 
+#include "auth/crypto.hpp"
 #include "auth/exceptions.hpp"
+#include "auth/rpc.hpp"
 #include "license/license.hpp"
+#include "system/transaction.hpp"
 #include "utils/flag_validation.hpp"
-#include "utils/logging.hpp"
 #include "utils/message.hpp"
 #include "utils/settings.hpp"
 #include "utils/string.hpp"
@@ -43,9 +44,89 @@ DEFINE_VALIDATED_int32(auth_module_timeout_ms, 10000,
                        FLAG_IN_RANGE(100, 1800000));
 
 namespace memgraph::auth {
+
+namespace {
+#ifdef MG_ENTERPRISE
+/**
+ * REPLICATION SYSTEM ACTION IMPLEMENTATIONS
+ */
+struct UpdateAuthData : memgraph::system::ISystemAction {
+  explicit UpdateAuthData(User user) : user_{std::move(user)}, role_{std::nullopt} {}
+  explicit UpdateAuthData(Role role) : user_{std::nullopt}, role_{std::move(role)} {}
+
+  void DoDurability() override { /* Done during Auth execution */
+  }
+
+  bool DoReplication(replication::ReplicationClient &client, const utils::UUID &main_uuid,
+                     replication::ReplicationEpoch const &epoch,
+                     memgraph::system::Transaction const &txn) const override {
+    auto check_response = [](const replication::UpdateAuthDataRes &response) { return response.success; };
+    if (user_) {
+      return client.SteamAndFinalizeDelta<replication::UpdateAuthDataRpc>(
+          check_response, main_uuid, std::string{epoch.id()}, txn.last_committed_system_timestamp(), txn.timestamp(),
+          *user_);
+    }
+    if (role_) {
+      return client.SteamAndFinalizeDelta<replication::UpdateAuthDataRpc>(
+          check_response, main_uuid, std::string{epoch.id()}, txn.last_committed_system_timestamp(), txn.timestamp(),
+          *role_);
+    }
+    // Should never get here
+    MG_ASSERT(false, "Trying to update auth data that is not a user nor a role");
+    return {};
+  }
+
+  void PostReplication(replication::RoleMainData &mainData) const override {}
+
+ private:
+  std::optional<User> user_;
+  std::optional<Role> role_;
+};
+
+struct DropAuthData : memgraph::system::ISystemAction {
+  enum class AuthDataType { USER, ROLE };
+
+  explicit DropAuthData(AuthDataType type, std::string_view name) : type_{type}, name_{name} {}
+
+  void DoDurability() override { /* Done during Auth execution */
+  }
+
+  bool DoReplication(replication::ReplicationClient &client, const utils::UUID &main_uuid,
+                     replication::ReplicationEpoch const &epoch,
+                     memgraph::system::Transaction const &txn) const override {
+    auto check_response = [](const replication::DropAuthDataRes &response) { return response.success; };
+
+    memgraph::replication::DropAuthDataReq::DataType type{};
+    switch (type_) {
+      case AuthDataType::USER:
+        type = memgraph::replication::DropAuthDataReq::DataType::USER;
+        break;
+      case AuthDataType::ROLE:
+        type = memgraph::replication::DropAuthDataReq::DataType::ROLE;
+        break;
+    }
+    return client.SteamAndFinalizeDelta<replication::DropAuthDataRpc>(
+        check_response, main_uuid, std::string{epoch.id()}, txn.last_committed_system_timestamp(), txn.timestamp(),
+        type, name_);
+  }
+  void PostReplication(replication::RoleMainData &mainData) const override {}
+
+ private:
+  AuthDataType type_;
+  std::string name_;
+};
+#endif
+
+/**
+ * CONSTANTS
+ */
 const std::string kUserPrefix = "user:";
 const std::string kRolePrefix = "role:";
 const std::string kLinkPrefix = "link:";
+const std::string kVersion = "version";
+
+static constexpr auto kVersionV1 = "V1";
+}  // namespace
 
 /**
  * All data stored in the `Auth` storage is stored in an underlying
@@ -64,7 +145,59 @@ const std::string kLinkPrefix = "link:";
  * key="link:<username>", value="<rolename>"
  */
 
-Auth::Auth(const std::string &storage_directory) : storage_(storage_directory), module_(FLAGS_auth_module_executable) {}
+namespace {
+void MigrateVersions(kvstore::KVStore &store) {
+  static constexpr auto kPasswordHashV0V1 = "password_hash";
+  auto version_str = store.Get(kVersion);
+
+  if (!version_str) {
+    using namespace std::string_literals;
+
+    // pre versioning, add version to the store
+    auto puts = std::map<std::string, std::string>{{kVersion, kVersionV1}};
+
+    // also add hash kind into durability
+
+    auto it = store.begin(kUserPrefix);
+    auto const e = store.end(kUserPrefix);
+
+    if (it != e) {
+      const auto hash_algo = CurrentHashAlgorithm();
+      spdlog::info("Updating auth durability, assuming previously stored as {}", AsString(hash_algo));
+
+      for (; it != e; ++it) {
+        auto const &[key, value] = *it;
+        try {
+          auto user_data = nlohmann::json::parse(value);
+
+          auto password_hash = user_data[kPasswordHashV0V1];
+          if (!password_hash.is_string()) {
+            throw AuthException("Couldn't load user data!");
+          }
+          // upgrade the password_hash to include the hash algortihm
+          if (password_hash.empty()) {
+            user_data[kPasswordHashV0V1] = nullptr;
+          } else {
+            user_data[kPasswordHashV0V1] = HashedPassword{hash_algo, password_hash};
+          }
+          puts.emplace(key, user_data.dump());
+        } catch (const nlohmann::json::parse_error &e) {
+          throw AuthException("Couldn't load user data!");
+        }
+      }
+    }
+
+    // Perform migration to V1
+    store.PutMultiple(puts);
+    version_str = kVersionV1;
+  }
+}
+};  // namespace
+
+Auth::Auth(std::string storage_directory, Config config)
+    : storage_(std::move(storage_directory)), module_(FLAGS_auth_module_executable), config_{std::move(config)} {
+  MigrateVersions(storage_);
+}
 
 std::optional<User> Auth::Authenticate(const std::string &username, const std::string &password) {
   if (module_.IsUsed()) {
@@ -95,6 +228,12 @@ std::optional<User> Auth::Authenticate(const std::string &username, const std::s
     // Authenticate the user.
     if (!is_authenticated) return std::nullopt;
 
+    /**
+     * TODO
+     * The auth module should not update auth data.
+     * There is now way to replicate it and we should not be storing sensitive data if we don't have to.
+     */
+
     // Find or create the user and return it.
     auto user = GetUser(username);
     if (!user) {
@@ -113,7 +252,7 @@ std::optional<User> Auth::Authenticate(const std::string &username, const std::s
         return std::nullopt;
       }
     } else {
-      user->UpdatePassword(password);
+      UpdatePassword(*user, password);
     }
     if (FLAGS_auth_module_manage_roles) {
       if (!rolename.empty()) {
@@ -155,6 +294,10 @@ std::optional<User> Auth::Authenticate(const std::string &username, const std::s
                                           username, "https://memgr.ph/auth"));
       return std::nullopt;
     }
+    if (user->UpgradeHash(password)) {
+      SaveUser(*user);
+    }
+
     return user;
   }
 }
@@ -183,7 +326,7 @@ std::optional<User> Auth::GetUser(const std::string &username_orig) const {
   return user;
 }
 
-void Auth::SaveUser(const User &user) {
+void Auth::SaveUser(const User &user, system::Transaction *system_tx) {
   bool success = false;
   if (const auto *role = user.role(); role != nullptr) {
     success = storage_.PutMultiple(
@@ -195,26 +338,72 @@ void Auth::SaveUser(const User &user) {
   if (!success) {
     throw AuthException("Couldn't save user '{}'!", user.username());
   }
+  // All changes to the user end up calling this function, so no need to add a delta anywhere else
+  if (system_tx) {
+#ifdef MG_ENTERPRISE
+    system_tx->AddAction<UpdateAuthData>(user);
+#endif
+  }
 }
 
-std::optional<User> Auth::AddUser(const std::string &username, const std::optional<std::string> &password) {
+void Auth::UpdatePassword(auth::User &user, const std::optional<std::string> &password) {
+  // Check if null
+  if (!password) {
+    if (!config_.password_permit_null) {
+      throw AuthException("Null passwords aren't permitted!");
+    }
+  } else {
+    // Check if compliant with our filter
+    if (config_.custom_password_regex) {
+      if (const auto license_check_result = license::global_license_checker.IsEnterpriseValid(utils::global_settings);
+          license_check_result.HasError()) {
+        throw AuthException(
+            "Custom password regex is a Memgraph Enterprise feature. Please set the config "
+            "(\"--auth-password-strength-regex\") to its default value (\"{}\") or remove the flag.\n{}",
+            glue::kDefaultPasswordRegex,
+            license::LicenseCheckErrorToString(license_check_result.GetError(), "password regex"));
+      }
+    }
+    if (!std::regex_match(*password, config_.password_regex)) {
+      throw AuthException(
+          "The user password doesn't conform to the required strength! Regex: "
+          "\"{}\"",
+          config_.password_regex_str);
+    }
+  }
+
+  // All checks passed; update
+  user.UpdatePassword(password);
+}
+
+std::optional<User> Auth::AddUser(const std::string &username, const std::optional<std::string> &password,
+                                  system::Transaction *system_tx) {
+  if (!NameRegexMatch(username)) {
+    throw AuthException("Invalid user name.");
+  }
   auto existing_user = GetUser(username);
   if (existing_user) return std::nullopt;
   auto existing_role = GetRole(username);
   if (existing_role) return std::nullopt;
   auto new_user = User(username);
-  new_user.UpdatePassword(password);
-  SaveUser(new_user);
+  UpdatePassword(new_user, password);
+  SaveUser(new_user, system_tx);
   return new_user;
 }
 
-bool Auth::RemoveUser(const std::string &username_orig) {
+bool Auth::RemoveUser(const std::string &username_orig, system::Transaction *system_tx) {
   auto username = utils::ToLowerCase(username_orig);
   if (!storage_.Get(kUserPrefix + username)) return false;
   std::vector<std::string> keys({kLinkPrefix + username, kUserPrefix + username});
   if (!storage_.DeleteMultiple(keys)) {
     throw AuthException("Couldn't remove user '{}'!", username);
   }
+  // Handling drop user delta
+  if (system_tx) {
+#ifdef MG_ENTERPRISE
+    system_tx->AddAction<DropAuthData>(DropAuthData::AuthDataType::USER, username);
+#endif
+  }
   return true;
 }
 
@@ -231,6 +420,19 @@ std::vector<auth::User> Auth::AllUsers() const {
   return ret;
 }
 
+std::vector<std::string> Auth::AllUsernames() const {
+  std::vector<std::string> ret;
+  for (auto it = storage_.begin(kUserPrefix); it != storage_.end(kUserPrefix); ++it) {
+    auto username = it->first.substr(kUserPrefix.size());
+    if (username != utils::ToLowerCase(username)) continue;
+    auto user = GetUser(username);
+    if (user) {
+      ret.push_back(username);
+    }
+  }
+  return ret;
+}
+
 bool Auth::HasUsers() const { return storage_.begin(kUserPrefix) != storage_.end(kUserPrefix); }
 
 std::optional<Role> Auth::GetRole(const std::string &rolename_orig) const {
@@ -248,21 +450,30 @@ std::optional<Role> Auth::GetRole(const std::string &rolename_orig) const {
   return Role::Deserialize(data);
 }
 
-void Auth::SaveRole(const Role &role) {
+void Auth::SaveRole(const Role &role, system::Transaction *system_tx) {
   if (!storage_.Put(kRolePrefix + role.rolename(), role.Serialize().dump())) {
     throw AuthException("Couldn't save role '{}'!", role.rolename());
   }
+  // All changes to the role end up calling this function, so no need to add a delta anywhere else
+  if (system_tx) {
+#ifdef MG_ENTERPRISE
+    system_tx->AddAction<UpdateAuthData>(role);
+#endif
+  }
 }
 
-std::optional<Role> Auth::AddRole(const std::string &rolename) {
+std::optional<Role> Auth::AddRole(const std::string &rolename, system::Transaction *system_tx) {
+  if (!NameRegexMatch(rolename)) {
+    throw AuthException("Invalid role name.");
+  }
   if (auto existing_role = GetRole(rolename)) return std::nullopt;
   if (auto existing_user = GetUser(rolename)) return std::nullopt;
   auto new_role = Role(rolename);
-  SaveRole(new_role);
+  SaveRole(new_role, system_tx);
   return new_role;
 }
 
-bool Auth::RemoveRole(const std::string &rolename_orig) {
+bool Auth::RemoveRole(const std::string &rolename_orig, system::Transaction *system_tx) {
   auto rolename = utils::ToLowerCase(rolename_orig);
   if (!storage_.Get(kRolePrefix + rolename)) return false;
   std::vector<std::string> keys;
@@ -275,6 +486,12 @@ bool Auth::RemoveRole(const std::string &rolename_orig) {
   if (!storage_.DeleteMultiple(keys)) {
     throw AuthException("Couldn't remove role '{}'!", rolename);
   }
+  // Handling drop role delta
+  if (system_tx) {
+#ifdef MG_ENTERPRISE
+    system_tx->AddAction<DropAuthData>(DropAuthData::AuthDataType::ROLE, rolename);
+#endif
+  }
   return true;
 }
 
@@ -292,6 +509,18 @@ std::vector<auth::Role> Auth::AllRoles() const {
   return ret;
 }
 
+std::vector<std::string> Auth::AllRolenames() const {
+  std::vector<std::string> ret;
+  for (auto it = storage_.begin(kRolePrefix); it != storage_.end(kRolePrefix); ++it) {
+    auto rolename = it->first.substr(kRolePrefix.size());
+    if (rolename != utils::ToLowerCase(rolename)) continue;
+    if (auto role = GetRole(rolename)) {
+      ret.push_back(rolename);
+    }
+  }
+  return ret;
+}
+
 std::vector<auth::User> Auth::AllUsersForRole(const std::string &rolename_orig) const {
   const auto rolename = utils::ToLowerCase(rolename_orig);
   std::vector<auth::User> ret;
@@ -311,52 +540,67 @@ std::vector<auth::User> Auth::AllUsersForRole(const std::string &rolename_orig)
 }
 
 #ifdef MG_ENTERPRISE
-bool Auth::GrantDatabaseToUser(const std::string &db, const std::string &name) {
+bool Auth::GrantDatabaseToUser(const std::string &db, const std::string &name, system::Transaction *system_tx) {
   if (auto user = GetUser(name)) {
     if (db == kAllDatabases) {
       user->db_access().GrantAll();
     } else {
       user->db_access().Add(db);
     }
-    SaveUser(*user);
+    SaveUser(*user, system_tx);
     return true;
   }
   return false;
 }
 
-bool Auth::RevokeDatabaseFromUser(const std::string &db, const std::string &name) {
+bool Auth::RevokeDatabaseFromUser(const std::string &db, const std::string &name, system::Transaction *system_tx) {
   if (auto user = GetUser(name)) {
     if (db == kAllDatabases) {
       user->db_access().DenyAll();
     } else {
       user->db_access().Remove(db);
     }
-    SaveUser(*user);
+    SaveUser(*user, system_tx);
     return true;
   }
   return false;
 }
 
-void Auth::DeleteDatabase(const std::string &db) {
+void Auth::DeleteDatabase(const std::string &db, system::Transaction *system_tx) {
   for (auto it = storage_.begin(kUserPrefix); it != storage_.end(kUserPrefix); ++it) {
     auto username = it->first.substr(kUserPrefix.size());
     if (auto user = GetUser(username)) {
       user->db_access().Delete(db);
-      SaveUser(*user);
+      SaveUser(*user, system_tx);
     }
   }
 }
 
-bool Auth::SetMainDatabase(std::string_view db, const std::string &name) {
+bool Auth::SetMainDatabase(std::string_view db, const std::string &name, system::Transaction *system_tx) {
   if (auto user = GetUser(name)) {
     if (!user->db_access().SetDefault(db)) {
       throw AuthException("Couldn't set default database '{}' for user '{}'!", db, name);
     }
-    SaveUser(*user);
+    SaveUser(*user, system_tx);
     return true;
   }
   return false;
 }
 #endif
 
+bool Auth::NameRegexMatch(const std::string &user_or_role) const {
+  if (config_.custom_name_regex) {
+    if (const auto license_check_result =
+            memgraph::license::global_license_checker.IsEnterpriseValid(memgraph::utils::global_settings);
+        license_check_result.HasError()) {
+      throw memgraph::auth::AuthException(
+          "Custom user/role regex is a Memgraph Enterprise feature. Please set the config "
+          "(\"--auth-user-or-role-name-regex\") to its default value (\"{}\") or remove the flag.\n{}",
+          glue::kDefaultUserRoleRegex,
+          memgraph::license::LicenseCheckErrorToString(license_check_result.GetError(), "user/role regex"));
+    }
+  }
+  return std::regex_match(user_or_role, config_.name_regex);
+}
+
 }  // namespace memgraph::auth

src/auth/auth.hpp

@@ -1,4 +1,4 @@
-// Copyright 2023 Memgraph Ltd.
+// Copyright 2024 Memgraph Ltd.
 //
 // Licensed as a Memgraph Enterprise file under the Memgraph Enterprise
 // License (the "License"); by using this file, you agree to be bound by the terms of the License, and you may not use
@@ -10,16 +10,23 @@
 
 #include <mutex>
 #include <optional>
+#include <regex>
 #include <vector>
 
 #include "auth/exceptions.hpp"
 #include "auth/models.hpp"
 #include "auth/module.hpp"
+#include "glue/auth_global.hpp"
 #include "kvstore/kvstore.hpp"
+#include "system/action.hpp"
 #include "utils/settings.hpp"
+#include "utils/synchronized.hpp"
 
 namespace memgraph::auth {
 
+class Auth;
+using SynchedAuth = memgraph::utils::Synchronized<memgraph::auth::Auth, memgraph::utils::WritePrioritizedRWLock>;
+
 static const constexpr char *const kAllDatabases = "*";
 
 /**
@@ -31,7 +38,47 @@ static const constexpr char *const kAllDatabases = "*";
  */
 class Auth final {
  public:
-  explicit Auth(const std::string &storage_directory);
+  struct Config {
+    Config() {}
+    Config(std::string name_regex, std::string password_regex, bool password_permit_null)
+        : name_regex_str{std::move(name_regex)},
+          password_regex_str{std::move(password_regex)},
+          password_permit_null{password_permit_null},
+          custom_name_regex{name_regex_str != glue::kDefaultUserRoleRegex},
+          name_regex{name_regex_str},
+          custom_password_regex{password_regex_str != glue::kDefaultPasswordRegex},
+          password_regex{password_regex_str} {}
+
+    std::string name_regex_str{glue::kDefaultUserRoleRegex};
+    std::string password_regex_str{glue::kDefaultPasswordRegex};
+    bool password_permit_null{true};
+
+   private:
+    friend class Auth;
+    bool custom_name_regex{false};
+    std::regex name_regex{name_regex_str};
+    bool custom_password_regex{false};
+    std::regex password_regex{password_regex_str};
+  };
+
+  explicit Auth(std::string storage_directory, Config config);
+
+  /**
+   * @brief Set the Config object
+   *
+   * @param config
+   */
+  void SetConfig(Config config) {
+    // NOTE: The Auth class itself is not thread-safe, higher-level code needs to synchronize it when using it.
+    config_ = std::move(config);
+  }
+
+  /**
+   * @brief
+   *
+   * @return Config
+   */
+  Config GetConfig() const { return config_; }
 
   /**
    * Authenticates a user using his username and password.
@@ -61,7 +108,7 @@ class Auth final {
    *
    * @throw AuthException if unable to save the user.
    */
-  void SaveUser(const User &user);
+  void SaveUser(const User &user, system::Transaction *system_tx = nullptr);
 
   /**
    * Creates a user if the user doesn't exist.
@@ -72,7 +119,8 @@ class Auth final {
    * @return a user when the user is created, nullopt if the user exists
    * @throw AuthException if unable to save the user.
    */
-  std::optional<User> AddUser(const std::string &username, const std::optional<std::string> &password = std::nullopt);
+  std::optional<User> AddUser(const std::string &username, const std::optional<std::string> &password = std::nullopt,
+                              system::Transaction *system_tx = nullptr);
 
   /**
    * Removes a user from the storage.
@@ -83,7 +131,15 @@ class Auth final {
    *         doesn't exist
    * @throw AuthException if unable to remove the user.
    */
-  bool RemoveUser(const std::string &username);
+  bool RemoveUser(const std::string &username, system::Transaction *system_tx = nullptr);
+
+  /**
+   * @brief
+   *
+   * @param user
+   * @param password
+   */
+  void UpdatePassword(auth::User &user, const std::optional<std::string> &password);
 
   /**
    * Gets all users from the storage.
@@ -93,6 +149,13 @@ class Auth final {
    */
   std::vector<User> AllUsers() const;
 
+  /**
+   * @brief
+   *
+   * @return std::vector<std::string>
+   */
+  std::vector<std::string> AllUsernames() const;
+
   /**
    * Returns whether there are users in the storage.
    *
@@ -117,7 +180,7 @@ class Auth final {
    *
    * @throw AuthException if unable to save the role.
    */
-  void SaveRole(const Role &role);
+  void SaveRole(const Role &role, system::Transaction *system_tx = nullptr);
 
   /**
    * Creates a role if the role doesn't exist.
@@ -127,7 +190,7 @@ class Auth final {
    * @return a role when the role is created, nullopt if the role exists
    * @throw AuthException if unable to save the role.
    */
-  std::optional<Role> AddRole(const std::string &rolename);
+  std::optional<Role> AddRole(const std::string &rolename, system::Transaction *system_tx = nullptr);
 
   /**
    * Removes a role from the storage.
@@ -138,7 +201,7 @@ class Auth final {
    *         doesn't exist
    * @throw AuthException if unable to remove the role.
    */
-  bool RemoveRole(const std::string &rolename);
+  bool RemoveRole(const std::string &rolename, system::Transaction *system_tx = nullptr);
 
   /**
    * Gets all roles from the storage.
@@ -148,6 +211,13 @@ class Auth final {
    */
   std::vector<Role> AllRoles() const;
 
+  /**
+   * @brief
+   *
+   * @return std::vector<std::string>
+   */
+  std::vector<std::string> AllRolenames() const;
+
   /**
    * Gets all users for a role from the storage.
    *
@@ -167,7 +237,7 @@ class Auth final {
    * @return true on success
    * @throw AuthException if unable to find or update the user
    */
-  bool RevokeDatabaseFromUser(const std::string &db, const std::string &name);
+  bool RevokeDatabaseFromUser(const std::string &db, const std::string &name, system::Transaction *system_tx = nullptr);
 
   /**
    * @brief Grant access to individual database for a user.
@@ -177,7 +247,7 @@ class Auth final {
    * @return true on success
    * @throw AuthException if unable to find or update the user
    */
-  bool GrantDatabaseToUser(const std::string &db, const std::string &name);
+  bool GrantDatabaseToUser(const std::string &db, const std::string &name, system::Transaction *system_tx = nullptr);
 
   /**
    * @brief Delete a database from all users.
@@ -185,7 +255,7 @@ class Auth final {
    * @param db name of the database to delete
    * @throw AuthException if unable to read data
    */
-  void DeleteDatabase(const std::string &db);
+  void DeleteDatabase(const std::string &db, system::Transaction *system_tx = nullptr);
 
   /**
    * @brief Set main database for an individual user.
@@ -195,14 +265,24 @@ class Auth final {
    * @return true on success
    * @throw AuthException if unable to find or update the user
    */
-  bool SetMainDatabase(std::string_view db, const std::string &name);
+  bool SetMainDatabase(std::string_view db, const std::string &name, system::Transaction *system_tx = nullptr);
 #endif
 
  private:
+  /**
+   * @brief
+   *
+   * @param user_or_role
+   * @return true
+   * @return false
+   */
+  bool NameRegexMatch(const std::string &user_or_role) const;
+
   // Even though the `kvstore::KVStore` class is guaranteed to be thread-safe,
   // Auth is not thread-safe because modifying users and roles might require
   // more than one operation on the storage.
   kvstore::KVStore storage_;
   auth::Module module_;
+  Config config_;
 };
 }  // namespace memgraph::auth

src/auth/crypto.cpp

@@ -1,4 +1,4 @@
-// Copyright 2023 Memgraph Ltd.
+// Copyright 2024 Memgraph Ltd.
 //
 // Licensed as a Memgraph Enterprise file under the Memgraph Enterprise
 // License (the "License"); by using this file, you agree to be bound by the terms of the License, and you may not use
@@ -22,10 +22,14 @@
 
 namespace {
 using namespace std::literals;
-inline constexpr std::array password_encryption_mappings{
-    std::pair{"bcrypt"sv, memgraph::auth::PasswordEncryptionAlgorithm::BCRYPT},
-    std::pair{"sha256"sv, memgraph::auth::PasswordEncryptionAlgorithm::SHA256},
-    std::pair{"sha256-multiple"sv, memgraph::auth::PasswordEncryptionAlgorithm::SHA256_MULTIPLE}};
+
+constexpr auto kHashAlgo = "hash_algo";
+constexpr auto kPasswordHash = "password_hash";
+
+inline constexpr std::array password_hash_mappings{
+    std::pair{"bcrypt"sv, memgraph::auth::PasswordHashAlgorithm::BCRYPT},
+    std::pair{"sha256"sv, memgraph::auth::PasswordHashAlgorithm::SHA256},
+    std::pair{"sha256-multiple"sv, memgraph::auth::PasswordHashAlgorithm::SHA256_MULTIPLE}};
 
 inline constexpr uint64_t ONE_SHA_ITERATION = 1;
 inline constexpr uint64_t MULTIPLE_SHA_ITERATIONS = 1024;
@@ -35,7 +39,7 @@ inline constexpr uint64_t MULTIPLE_SHA_ITERATIONS = 1024;
 DEFINE_VALIDATED_string(password_encryption_algorithm, "bcrypt",
                         "The password encryption algorithm used for authentication.", {
                           if (const auto result =
-                                  memgraph::utils::IsValidEnumValueString(value, password_encryption_mappings);
+                                  memgraph::utils::IsValidEnumValueString(value, password_hash_mappings);
                               result.HasError()) {
                             const auto error = result.GetError();
                             switch (error) {
@@ -45,7 +49,7 @@ DEFINE_VALIDATED_string(password_encryption_algorithm, "bcrypt",
                               }
                               case memgraph::utils::ValidationError::InvalidValue: {
                                 std::cout << "Invalid value for password encryption algorithm. Allowed values: "
-                                          << memgraph::utils::GetAllowedEnumValuesString(password_encryption_mappings)
+                                          << memgraph::utils::GetAllowedEnumValuesString(password_hash_mappings)
                                           << std::endl;
                                 break;
                               }
@@ -58,7 +62,7 @@ DEFINE_VALIDATED_string(password_encryption_algorithm, "bcrypt",
 
 namespace memgraph::auth {
 namespace BCrypt {
-std::string EncryptPassword(const std::string &password) {
+std::string HashPassword(const std::string &password) {
   char salt[BCRYPT_HASHSIZE];
   char hash[BCRYPT_HASHSIZE];
 
@@ -86,16 +90,30 @@ bool VerifyPassword(const std::string &password, const std::string &hash) {
 }  // namespace BCrypt
 
 namespace SHA {
+
+namespace {
+
+constexpr auto SHA_LENGTH = 64U;
+constexpr auto SALT_SIZE = 16U;
+constexpr auto SALT_SIZE_DURABLE = SALT_SIZE * 2;
+
 #if OPENSSL_VERSION_MAJOR >= 3
-std::string EncryptPasswordOpenSSL3(const std::string &password, const uint64_t number_of_iterations) {
+std::string HashPasswordOpenSSL3(std::string_view password, const uint64_t number_of_iterations,
+                                 std::string_view salt) {
   unsigned char hash[SHA256_DIGEST_LENGTH];
 
   EVP_MD_CTX *ctx = EVP_MD_CTX_new();
   EVP_MD *md = EVP_MD_fetch(nullptr, "SHA2-256", nullptr);
 
   EVP_DigestInit_ex(ctx, md, nullptr);
+
+  if (!salt.empty()) {
+    DMG_ASSERT(salt.size() == SALT_SIZE);
+    EVP_DigestUpdate(ctx, salt.data(), salt.size());
+  }
+
   for (auto i = 0; i < number_of_iterations; i++) {
-    EVP_DigestUpdate(ctx, password.c_str(), password.size());
+    EVP_DigestUpdate(ctx, password.data(), password.size());
   }
   EVP_DigestFinal_ex(ctx, hash, nullptr);
 
@@ -103,6 +121,11 @@ std::string EncryptPasswordOpenSSL3(const std::string &password, const uint64_t
   EVP_MD_CTX_free(ctx);
 
   std::stringstream result_stream;
+
+  for (unsigned char salt_char : salt) {
+    result_stream << std::hex << std::setw(2) << std::setfill('0') << (((unsigned int)salt_char) & 0xFFU);
+  }
+
   for (auto hash_char : hash) {
     result_stream << std::hex << std::setw(2) << std::setfill('0') << (int)hash_char;
   }
@@ -110,17 +133,27 @@ std::string EncryptPasswordOpenSSL3(const std::string &password, const uint64_t
   return result_stream.str();
 }
 #else
-std::string EncryptPasswordOpenSSL1_1(const std::string &password, const uint64_t number_of_iterations) {
+std::string HashPasswordOpenSSL1_1(std::string_view password, const uint64_t number_of_iterations,
+                                   std::string_view salt) {
   unsigned char hash[SHA256_DIGEST_LENGTH];
 
   SHA256_CTX sha256;
   SHA256_Init(&sha256);
+
+  if (!salt.empty()) {
+    DMG_ASSERT(salt.size() == SALT_SIZE);
+    SHA256_Update(&sha256, salt.data(), salt.size());
+  }
+
   for (auto i = 0; i < number_of_iterations; i++) {
-    SHA256_Update(&sha256, password.c_str(), password.size());
+    SHA256_Update(&sha256, password.data(), password.size());
   }
   SHA256_Final(hash, &sha256);
 
   std::stringstream ss;
+  for (unsigned char salt_char : salt) {
+    ss << std::hex << std::setw(2) << std::setfill('0') << (((unsigned int)salt_char) & 0xFFU);
+  }
   for (auto hash_char : hash) {
     ss << std::hex << std::setw(2) << std::setfill('0') << (int)hash_char;
   }
@@ -129,55 +162,144 @@ std::string EncryptPasswordOpenSSL1_1(const std::string &password, const uint64_
 }
 #endif
 
-std::string EncryptPassword(const std::string &password, const uint64_t number_of_iterations) {
+std::string HashPassword(std::string_view password, const uint64_t number_of_iterations, std::string_view salt) {
 #if OPENSSL_VERSION_MAJOR >= 3
-  return EncryptPasswordOpenSSL3(password, number_of_iterations);
+  return HashPasswordOpenSSL3(password, number_of_iterations, salt);
 #else
-  return EncryptPasswordOpenSSL1_1(password, number_of_iterations);
+  return HashPasswordOpenSSL1_1(password, number_of_iterations, salt);
 #endif
 }
 
-bool VerifyPassword(const std::string &password, const std::string &hash, const uint64_t number_of_iterations) {
-  auto password_hash = EncryptPassword(password, number_of_iterations);
+auto ExtractSalt(std::string_view salt_durable) -> std::array<char, SALT_SIZE> {
+  static_assert(SALT_SIZE_DURABLE % 2 == 0);
+  static_assert(SALT_SIZE_DURABLE / 2 == SALT_SIZE);
+
+  MG_ASSERT(salt_durable.size() == SALT_SIZE_DURABLE);
+  auto const *b = salt_durable.cbegin();
+  auto const *const e = salt_durable.cend();
+
+  auto salt = std::array<char, SALT_SIZE>{};
+  auto *inserter = salt.begin();
+
+  auto const toval = [](char a) -> uint8_t {
+    if ('0' <= a && a <= '9') {
+      return a - '0';
+    }
+    if ('a' <= a && a <= 'f') {
+      return 10 + (a - 'a');
+    }
+    MG_ASSERT(false, "Currupt hash, can't extract salt");
+    __builtin_unreachable();
+  };
+
+  for (; b != e; b += 2, ++inserter) {
+    *inserter = static_cast<char>(static_cast<uint8_t>(toval(b[0]) << 4U) | toval(b[1]));
+  }
+  return salt;
+}
+
+bool IsSalted(std::string_view hash) { return hash.size() == SHA_LENGTH + SALT_SIZE_DURABLE; }
+
+bool VerifyPassword(std::string_view password, std::string_view hash, const uint64_t number_of_iterations) {
+  auto password_hash = std::invoke([&] {
+    if (hash.size() == SHA_LENGTH) [[unlikely]] {
+      // Just SHA256
+      return HashPassword(password, number_of_iterations, {});
+    } else {
+      // SHA256 + SALT
+      MG_ASSERT(IsSalted(hash));
+      auto const salt_durable = std::string_view{hash.data(), SALT_SIZE_DURABLE};
+      std::array<char, SALT_SIZE> salt = ExtractSalt(salt_durable);
+      return HashPassword(password, number_of_iterations, {salt.data(), salt.size()});
+    }
+  });
   return password_hash == hash;
 }
+
+}  // namespace
+
 }  // namespace SHA
 
-bool VerifyPassword(const std::string &password, const std::string &hash) {
-  const auto password_encryption_algorithm = utils::StringToEnum<PasswordEncryptionAlgorithm>(
-      FLAGS_password_encryption_algorithm, password_encryption_mappings);
+HashedPassword HashPassword(const std::string &password, std::optional<PasswordHashAlgorithm> override_algo) {
+  auto const hash_algo = override_algo.value_or(CurrentHashAlgorithm());
+  auto password_hash = std::invoke([&] {
+    switch (hash_algo) {
+      case PasswordHashAlgorithm::BCRYPT: {
+        return BCrypt::HashPassword(password);
+      }
+      case PasswordHashAlgorithm::SHA256:
+      case PasswordHashAlgorithm::SHA256_MULTIPLE: {
+        auto gen = std::mt19937(std::random_device{}());
+        auto salt = std::array<char, SHA::SALT_SIZE>{};
+        auto dis = std::uniform_int_distribution<unsigned char>(0, 255);
+        std::generate(salt.begin(), salt.end(), [&]() { return dis(gen); });
+        auto iterations = (hash_algo == PasswordHashAlgorithm::SHA256) ? ONE_SHA_ITERATION : MULTIPLE_SHA_ITERATIONS;
+        return SHA::HashPassword(password, iterations, {salt.data(), salt.size()});
+      }
+    }
+  });
+  return HashedPassword{hash_algo, std::move(password_hash)};
+};
 
-  if (!password_encryption_algorithm.has_value()) {
-    throw AuthException("Invalid password encryption flag '{}'!", FLAGS_password_encryption_algorithm);
+namespace {
+
+auto InternalParseHashAlgorithm(std::string_view algo) -> PasswordHashAlgorithm {
+  auto maybe_parsed = utils::StringToEnum<PasswordHashAlgorithm>(algo, password_hash_mappings);
+  if (!maybe_parsed) {
+    throw AuthException("Invalid password encryption '{}'!", algo);
   }
-
-  switch (password_encryption_algorithm.value()) {
-    case PasswordEncryptionAlgorithm::BCRYPT:
-      return BCrypt::VerifyPassword(password, hash);
-    case PasswordEncryptionAlgorithm::SHA256:
-      return SHA::VerifyPassword(password, hash, ONE_SHA_ITERATION);
-    case PasswordEncryptionAlgorithm::SHA256_MULTIPLE:
-      return SHA::VerifyPassword(password, hash, MULTIPLE_SHA_ITERATIONS);
-  }
-
-  throw AuthException("Invalid password encryption flag '{}'!", FLAGS_password_encryption_algorithm);
+  return *maybe_parsed;
 }
 
-std::string EncryptPassword(const std::string &password) {
-  const auto password_encryption_algorithm = utils::StringToEnum<PasswordEncryptionAlgorithm>(
-      FLAGS_password_encryption_algorithm, password_encryption_mappings);
+PasswordHashAlgorithm &InternalCurrentHashAlgorithm() {
+  static auto current = PasswordHashAlgorithm::BCRYPT;
+  static std::once_flag flag;
+  std::call_once(flag, [] { current = InternalParseHashAlgorithm(FLAGS_password_encryption_algorithm); });
+  return current;
+}
+}  // namespace
 
-  if (!password_encryption_algorithm.has_value()) {
-    throw AuthException("Invalid password encryption flag '{}'!", FLAGS_password_encryption_algorithm);
+auto CurrentHashAlgorithm() -> PasswordHashAlgorithm { return InternalCurrentHashAlgorithm(); }
+
+void SetHashAlgorithm(std::string_view algo) {
+  auto &current = InternalCurrentHashAlgorithm();
+  current = InternalParseHashAlgorithm(algo);
+}
+
+auto AsString(PasswordHashAlgorithm hash_algo) -> std::string_view {
+  return *utils::EnumToString<PasswordHashAlgorithm>(hash_algo, password_hash_mappings);
+}
+
+bool HashedPassword::VerifyPassword(const std::string &password) {
+  switch (hash_algo) {
+    case PasswordHashAlgorithm::BCRYPT:
+      return BCrypt::VerifyPassword(password, password_hash);
+    case PasswordHashAlgorithm::SHA256:
+      return SHA::VerifyPassword(password, password_hash, ONE_SHA_ITERATION);
+    case PasswordHashAlgorithm::SHA256_MULTIPLE:
+      return SHA::VerifyPassword(password, password_hash, MULTIPLE_SHA_ITERATIONS);
   }
+}
 
-  switch (password_encryption_algorithm.value()) {
-    case PasswordEncryptionAlgorithm::BCRYPT:
-      return BCrypt::EncryptPassword(password);
-    case PasswordEncryptionAlgorithm::SHA256:
-      return SHA::EncryptPassword(password, ONE_SHA_ITERATION);
-    case PasswordEncryptionAlgorithm::SHA256_MULTIPLE:
-      return SHA::EncryptPassword(password, MULTIPLE_SHA_ITERATIONS);
+void to_json(nlohmann::json &j, const HashedPassword &p) {
+  j = nlohmann::json{{kHashAlgo, p.hash_algo}, {kPasswordHash, p.password_hash}};
+}
+
+void from_json(const nlohmann::json &j, HashedPassword &p) {
+  // NOLINTNEXTLINE(cppcoreguidelines-init-variables)
+  PasswordHashAlgorithm hash_algo;
+  j.at(kHashAlgo).get_to(hash_algo);
+  auto password_hash = j.value(kPasswordHash, std::string());
+  p = HashedPassword{hash_algo, std::move(password_hash)};
+}
+
+bool HashedPassword::IsSalted() const {
+  switch (hash_algo) {
+    case PasswordHashAlgorithm::BCRYPT:
+      return true;
+    case PasswordHashAlgorithm::SHA256:
+    case PasswordHashAlgorithm::SHA256_MULTIPLE:
+      return SHA::IsSalted(password_hash);
   }
 }
 

src/auth/crypto.hpp

@@ -1,4 +1,4 @@
-// Copyright 2023 Memgraph Ltd.
+// Copyright 2024 Memgraph Ltd.
 //
 // Licensed as a Memgraph Enterprise file under the Memgraph Enterprise
 // License (the "License"); by using this file, you agree to be bound by the terms of the License, and you may not use
@@ -8,14 +8,45 @@
 
 #pragma once
 
+#include <json/json.hpp>
+#include <optional>
 #include <string>
 
 namespace memgraph::auth {
-enum class PasswordEncryptionAlgorithm : uint8_t { BCRYPT, SHA256, SHA256_MULTIPLE };
+/// Need to be stable, auth durability depends on this
+enum class PasswordHashAlgorithm : uint8_t { BCRYPT = 0, SHA256 = 1, SHA256_MULTIPLE = 2 };
 
-/// @throw AuthException if unable to encrypt the password.
-std::string EncryptPassword(const std::string &password);
+void SetHashAlgorithm(std::string_view algo);
 
-/// @throw AuthException if unable to verify the password.
-bool VerifyPassword(const std::string &password, const std::string &hash);
+auto CurrentHashAlgorithm() -> PasswordHashAlgorithm;
+
+auto AsString(PasswordHashAlgorithm hash_algo) -> std::string_view;
+
+struct HashedPassword {
+  HashedPassword() = default;
+  HashedPassword(PasswordHashAlgorithm hash_algo, std::string password_hash)
+      : hash_algo{hash_algo}, password_hash{std::move(password_hash)} {}
+  HashedPassword(HashedPassword const &) = default;
+  HashedPassword(HashedPassword &&) = default;
+  HashedPassword &operator=(HashedPassword const &) = default;
+  HashedPassword &operator=(HashedPassword &&) = default;
+
+  friend bool operator==(HashedPassword const &, HashedPassword const &) = default;
+
+  bool VerifyPassword(const std::string &password);
+
+  bool IsSalted() const;
+
+  auto HashAlgo() const -> PasswordHashAlgorithm { return hash_algo; }
+
+  friend void to_json(nlohmann::json &j, const HashedPassword &p);
+  friend void from_json(const nlohmann::json &j, HashedPassword &p);
+
+ private:
+  PasswordHashAlgorithm hash_algo{PasswordHashAlgorithm::BCRYPT};
+  std::string password_hash{};
+};
+
+/// @throw AuthException if unable to hash the password.
+HashedPassword HashPassword(const std::string &password, std::optional<PasswordHashAlgorithm> override_algo = {});
 }  // namespace memgraph::auth

src/auth/models.cpp

@@ -9,7 +9,6 @@
 #include "auth/models.hpp"
 
 #include <cstdint>
-#include <regex>
 #include <utility>
 
 #include <gflags/gflags.h>
@@ -21,22 +20,26 @@
 #include "query/constants.hpp"
 #include "spdlog/spdlog.h"
 #include "utils/cast.hpp"
-#include "utils/logging.hpp"
-#include "utils/settings.hpp"
 #include "utils/string.hpp"
 
-// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
-DEFINE_bool(auth_password_permit_null, true, "Set to false to disable null passwords.");
-
-inline constexpr std::string_view default_password_regex = ".+";
-// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
-DEFINE_string(auth_password_strength_regex, default_password_regex.data(),
-              "The regular expression that should be used to match the entire "
-              "entered password to ensure its strength.");
-
 namespace memgraph::auth {
 namespace {
 
+constexpr auto kRoleName = "rolename";
+constexpr auto kPermissions = "permissions";
+constexpr auto kGrants = "grants";
+constexpr auto kDenies = "denies";
+constexpr auto kUsername = "username";
+constexpr auto kPasswordHash = "password_hash";
+
+#ifdef MG_ENTERPRISE
+constexpr auto kGlobalPermission = "global_permission";
+constexpr auto kFineGrainedAccessHandler = "fine_grained_access_handler";
+constexpr auto kAllowAll = "allow_all";
+constexpr auto kDefault = "default";
+constexpr auto kDatabases = "databases";
+#endif
+
 // Constant list of all available permissions.
 const std::vector<Permission> kPermissionsAll = {Permission::MATCH,
                                                  Permission::CREATE,
@@ -245,8 +248,9 @@ std::vector<Permission> Permissions::GetDenies() const {
 
 nlohmann::json Permissions::Serialize() const {
   nlohmann::json data = nlohmann::json::object();
-  data["grants"] = grants_;
-  data["denies"] = denies_;
+
+  data[kGrants] = grants_;
+  data[kDenies] = denies_;
   return data;
 }
 
@@ -254,10 +258,10 @@ Permissions Permissions::Deserialize(const nlohmann::json &data) {
   if (!data.is_object()) {
     throw AuthException("Couldn't load permissions data!");
   }
-  if (!data["grants"].is_number_unsigned() || !data["denies"].is_number_unsigned()) {
+  if (!data[kGrants].is_number_unsigned() || !data[kDenies].is_number_unsigned()) {
     throw AuthException("Couldn't load permissions data!");
   }
-  return Permissions{data["grants"], data["denies"]};
+  return Permissions{data[kGrants], data[kDenies]};
 }
 
 uint64_t Permissions::grants() const { return grants_; }
@@ -319,8 +323,8 @@ nlohmann::json FineGrainedAccessPermissions::Serialize() const {
     return {};
   }
   nlohmann::json data = nlohmann::json::object();
-  data["permissions"] = permissions_;
-  data["global_permission"] = global_permission_.has_value() ? global_permission_.value() : -1;
+  data[kPermissions] = permissions_;
+  data[kGlobalPermission] = global_permission_.has_value() ? global_permission_.value() : -1;
   return data;
 }
 
@@ -333,13 +337,13 @@ FineGrainedAccessPermissions FineGrainedAccessPermissions::Deserialize(const nlo
   }
   std::optional<uint64_t> global_permission;
 
-  if (data["global_permission"].empty() || data["global_permission"] == -1) {
+  if (data[kGlobalPermission].empty() || data[kGlobalPermission] == -1) {
     global_permission = std::nullopt;
   } else {
-    global_permission = data["global_permission"];
+    global_permission = data[kGlobalPermission];
   }
 
-  return FineGrainedAccessPermissions(data["permissions"], global_permission);
+  return FineGrainedAccessPermissions(data[kPermissions], global_permission);
 }
 
 const std::unordered_map<std::string, uint64_t> &FineGrainedAccessPermissions::GetPermissions() const {
@@ -445,13 +449,13 @@ const FineGrainedAccessPermissions &Role::GetFineGrainedAccessEdgeTypePermission
 
 nlohmann::json Role::Serialize() const {
   nlohmann::json data = nlohmann::json::object();
-  data["rolename"] = rolename_;
-  data["permissions"] = permissions_.Serialize();
+  data[kRoleName] = rolename_;
+  data[kPermissions] = permissions_.Serialize();
 #ifdef MG_ENTERPRISE
   if (memgraph::license::global_license_checker.IsEnterpriseValidFast()) {
-    data["fine_grained_access_handler"] = fine_grained_access_handler_.Serialize();
+    data[kFineGrainedAccessHandler] = fine_grained_access_handler_.Serialize();
   } else {
-    data["fine_grained_access_handler"] = {};
+    data[kFineGrainedAccessHandler] = {};
   }
 #endif
   return data;
@@ -461,21 +465,21 @@ Role Role::Deserialize(const nlohmann::json &data) {
   if (!data.is_object()) {
     throw AuthException("Couldn't load role data!");
   }
-  if (!data["rolename"].is_string() || !data["permissions"].is_object()) {
+  if (!data[kRoleName].is_string() || !data[kPermissions].is_object()) {
     throw AuthException("Couldn't load role data!");
   }
-  auto permissions = Permissions::Deserialize(data["permissions"]);
+  auto permissions = Permissions::Deserialize(data[kPermissions]);
 #ifdef MG_ENTERPRISE
   if (memgraph::license::global_license_checker.IsEnterpriseValidFast()) {
     FineGrainedAccessHandler fine_grained_access_handler;
     // We can have an empty fine_grained if the user was created without a valid license
-    if (data["fine_grained_access_handler"].is_object()) {
-      fine_grained_access_handler = FineGrainedAccessHandler::Deserialize(data["fine_grained_access_handler"]);
+    if (data[kFineGrainedAccessHandler].is_object()) {
+      fine_grained_access_handler = FineGrainedAccessHandler::Deserialize(data[kFineGrainedAccessHandler]);
     }
-    return {data["rolename"], permissions, std::move(fine_grained_access_handler)};
+    return {data[kRoleName], permissions, std::move(fine_grained_access_handler)};
   }
 #endif
-  return {data["rolename"], permissions};
+  return {data[kRoleName], permissions};
 }
 
 bool operator==(const Role &first, const Role &second) {
@@ -545,10 +549,10 @@ const std::string &Databases::GetDefault() const {
 
 nlohmann::json Databases::Serialize() const {
   nlohmann::json data = nlohmann::json::object();
-  data["grants"] = grants_dbs_;
-  data["denies"] = denies_dbs_;
-  data["allow_all"] = allow_all_;
-  data["default"] = default_db_;
+  data[kGrants] = grants_dbs_;
+  data[kDenies] = denies_dbs_;
+  data[kAllowAll] = allow_all_;
+  data[kDefault] = default_db_;
   return data;
 }
 
@@ -556,22 +560,22 @@ Databases Databases::Deserialize(const nlohmann::json &data) {
   if (!data.is_object()) {
     throw AuthException("Couldn't load database data!");
   }
-  if (!data["grants"].is_structured() || !data["denies"].is_structured() || !data["allow_all"].is_boolean() ||
-      !data["default"].is_string()) {
+  if (!data[kGrants].is_structured() || !data[kDenies].is_structured() || !data[kAllowAll].is_boolean() ||
+      !data[kDefault].is_string()) {
     throw AuthException("Couldn't load database data!");
   }
-  return {data["allow_all"], data["grants"], data["denies"], data["default"]};
+  return {data[kAllowAll], data[kGrants], data[kDenies], data[kDefault]};
 }
 #endif
 
 User::User() = default;
 
 User::User(const std::string &username) : username_(utils::ToLowerCase(username)) {}
-User::User(const std::string &username, std::string password_hash, const Permissions &permissions)
+User::User(const std::string &username, std::optional<HashedPassword> password_hash, const Permissions &permissions)
     : username_(utils::ToLowerCase(username)), password_hash_(std::move(password_hash)), permissions_(permissions) {}
 
 #ifdef MG_ENTERPRISE
-User::User(const std::string &username, std::string password_hash, const Permissions &permissions,
+User::User(const std::string &username, std::optional<HashedPassword> password_hash, const Permissions &permissions,
            FineGrainedAccessHandler fine_grained_access_handler, Databases db_access)
     : username_(utils::ToLowerCase(username)),
       password_hash_(std::move(password_hash)),
@@ -581,38 +585,16 @@ User::User(const std::string &username, std::string password_hash, const Permiss
 #endif
 
 bool User::CheckPassword(const std::string &password) {
-  if (password_hash_.empty()) return true;
-  return VerifyPassword(password, password_hash_);
+  return password_hash_ ? password_hash_->VerifyPassword(password) : true;
 }
 
-void User::UpdatePassword(const std::optional<std::string> &password) {
+void User::UpdatePassword(const std::optional<std::string> &password,
+                          std::optional<PasswordHashAlgorithm> algo_override) {
   if (!password) {
-    if (!FLAGS_auth_password_permit_null) {
-      throw AuthException("Null passwords aren't permitted!");
-    }
-    password_hash_ = "";
+    password_hash_.reset();
     return;
   }
-
-  if (FLAGS_auth_password_strength_regex != default_password_regex) {
-    if (const auto license_check_result = license::global_license_checker.IsEnterpriseValid(utils::global_settings);
-        license_check_result.HasError()) {
-      throw AuthException(
-          "Custom password regex is a Memgraph Enterprise feature. Please set the config "
-          "(\"--auth-password-strength-regex\") to its default value (\"{}\") or remove the flag.\n{}",
-          default_password_regex,
-          license::LicenseCheckErrorToString(license_check_result.GetError(), "password regex"));
-    }
-  }
-  std::regex re(FLAGS_auth_password_strength_regex);
-  if (!std::regex_match(*password, re)) {
-    throw AuthException(
-        "The user password doesn't conform to the required strength! Regex: "
-        "\"{}\"",
-        FLAGS_auth_password_strength_regex);
-  }
-
-  password_hash_ = EncryptPassword(*password);
+  password_hash_ = HashPassword(*password, algo_override);
 }
 
 void User::SetRole(const Role &role) { role_.emplace(role); }
@@ -629,27 +611,49 @@ Permissions User::GetPermissions() const {
 
 #ifdef MG_ENTERPRISE
 FineGrainedAccessPermissions User::GetFineGrainedAccessLabelPermissions() const {
+  return Merge(GetUserFineGrainedAccessLabelPermissions(), GetRoleFineGrainedAccessLabelPermissions());
+}
+
+FineGrainedAccessPermissions User::GetFineGrainedAccessEdgeTypePermissions() const {
+  return Merge(GetUserFineGrainedAccessEdgeTypePermissions(), GetRoleFineGrainedAccessEdgeTypePermissions());
+}
+
+FineGrainedAccessPermissions User::GetUserFineGrainedAccessEdgeTypePermissions() const {
   if (!memgraph::license::global_license_checker.IsEnterpriseValidFast()) {
     return FineGrainedAccessPermissions{};
   }
 
-  if (role_) {
-    return Merge(role()->fine_grained_access_handler().label_permissions(),
-                 fine_grained_access_handler_.label_permissions());
+  return fine_grained_access_handler_.edge_type_permissions();
+}
+
+FineGrainedAccessPermissions User::GetUserFineGrainedAccessLabelPermissions() const {
+  if (!memgraph::license::global_license_checker.IsEnterpriseValidFast()) {
+    return FineGrainedAccessPermissions{};
   }
 
   return fine_grained_access_handler_.label_permissions();
 }
 
-FineGrainedAccessPermissions User::GetFineGrainedAccessEdgeTypePermissions() const {
+FineGrainedAccessPermissions User::GetRoleFineGrainedAccessEdgeTypePermissions() const {
   if (!memgraph::license::global_license_checker.IsEnterpriseValidFast()) {
     return FineGrainedAccessPermissions{};
   }
+
   if (role_) {
-    return Merge(role()->fine_grained_access_handler().edge_type_permissions(),
-                 fine_grained_access_handler_.edge_type_permissions());
+    return role()->fine_grained_access_handler().edge_type_permissions();
   }
-  return fine_grained_access_handler_.edge_type_permissions();
+  return FineGrainedAccessPermissions{};
+}
+
+FineGrainedAccessPermissions User::GetRoleFineGrainedAccessLabelPermissions() const {
+  if (!memgraph::license::global_license_checker.IsEnterpriseValidFast()) {
+    return FineGrainedAccessPermissions{};
+  }
+
+  if (role_) {
+    return role()->fine_grained_access_handler().label_permissions();
+  }
+  return FineGrainedAccessPermissions{};
 }
 #endif
 
@@ -671,16 +675,20 @@ const Role *User::role() const {
 
 nlohmann::json User::Serialize() const {
   nlohmann::json data = nlohmann::json::object();
-  data["username"] = username_;
-  data["password_hash"] = password_hash_;
-  data["permissions"] = permissions_.Serialize();
+  data[kUsername] = username_;
+  if (password_hash_.has_value()) {
+    data[kPasswordHash] = *password_hash_;
+  } else {
+    data[kPasswordHash] = nullptr;
+  }
+  data[kPermissions] = permissions_.Serialize();
 #ifdef MG_ENTERPRISE
   if (memgraph::license::global_license_checker.IsEnterpriseValidFast()) {
-    data["fine_grained_access_handler"] = fine_grained_access_handler_.Serialize();
-    data["databases"] = database_access_.Serialize();
+    data[kFineGrainedAccessHandler] = fine_grained_access_handler_.Serialize();
+    data[kDatabases] = database_access_.Serialize();
   } else {
-    data["fine_grained_access_handler"] = {};
-    data["databases"] = {};
+    data[kFineGrainedAccessHandler] = {};
+    data[kDatabases] = {};
   }
 #endif
   // The role shouldn't be serialized here, it is stored as a foreign key.
@@ -691,15 +699,23 @@ User User::Deserialize(const nlohmann::json &data) {
   if (!data.is_object()) {
     throw AuthException("Couldn't load user data!");
   }
-  if (!data["username"].is_string() || !data["password_hash"].is_string() || !data["permissions"].is_object()) {
+  auto password_hash_json = data[kPasswordHash];
+  if (!data[kUsername].is_string() || !(password_hash_json.is_object() || password_hash_json.is_null()) ||
+      !data[kPermissions].is_object()) {
     throw AuthException("Couldn't load user data!");
   }
-  auto permissions = Permissions::Deserialize(data["permissions"]);
+
+  std::optional<HashedPassword> password_hash{};
+  if (password_hash_json.is_object()) {
+    password_hash = password_hash_json.get<HashedPassword>();
+  }
+
+  auto permissions = Permissions::Deserialize(data[kPermissions]);
 #ifdef MG_ENTERPRISE
   if (memgraph::license::global_license_checker.IsEnterpriseValidFast()) {
     Databases db_access;
-    if (data["databases"].is_structured()) {
-      db_access = Databases::Deserialize(data["databases"]);
+    if (data[kDatabases].is_structured()) {
+      db_access = Databases::Deserialize(data[kDatabases]);
     } else {
       // Back-compatibility
       spdlog::warn("User without specified database access. Given access to the default database.");
@@ -708,13 +724,13 @@ User User::Deserialize(const nlohmann::json &data) {
     }
     FineGrainedAccessHandler fine_grained_access_handler;
     // We can have an empty fine_grained if the user was created without a valid license
-    if (data["fine_grained_access_handler"].is_object()) {
-      fine_grained_access_handler = FineGrainedAccessHandler::Deserialize(data["fine_grained_access_handler"]);
+    if (data[kFineGrainedAccessHandler].is_object()) {
+      fine_grained_access_handler = FineGrainedAccessHandler::Deserialize(data[kFineGrainedAccessHandler]);
     }
-    return {data["username"], data["password_hash"], permissions, std::move(fine_grained_access_handler), db_access};
+    return {data[kUsername], std::move(password_hash), permissions, std::move(fine_grained_access_handler), db_access};
   }
 #endif
-  return {data["username"], data["password_hash"], permissions};
+  return {data[kUsername], std::move(password_hash), permissions};
 }
 
 bool operator==(const User &first, const User &second) {

src/auth/models.hpp

@@ -15,6 +15,7 @@
 
 #include <json/json.hpp>
 #include <utility>
+#include "crypto.hpp"
 #include "dbms/constants.hpp"
 #include "utils/logging.hpp"
 
@@ -206,6 +207,8 @@ bool operator==(const FineGrainedAccessHandler &first, const FineGrainedAccessHa
 
 class Role final {
  public:
+  Role() = default;
+
   explicit Role(const std::string &rolename);
   Role(const std::string &rolename, const Permissions &permissions);
 #ifdef MG_ENTERPRISE
@@ -332,9 +335,9 @@ class User final {
   User();
 
   explicit User(const std::string &username);
-  User(const std::string &username, std::string password_hash, const Permissions &permissions);
+  User(const std::string &username, std::optional<HashedPassword> password_hash, const Permissions &permissions);
 #ifdef MG_ENTERPRISE
-  User(const std::string &username, std::string password_hash, const Permissions &permissions,
+  User(const std::string &username, std::optional<HashedPassword> password_hash, const Permissions &permissions,
        FineGrainedAccessHandler fine_grained_access_handler, Databases db_access = {});
 #endif
   User(const User &) = default;
@@ -346,8 +349,18 @@ class User final {
   /// @throw AuthException if unable to verify the password.
   bool CheckPassword(const std::string &password);
 
+  bool UpgradeHash(const std::string password) {
+    if (!password_hash_) return false;
+    if (password_hash_->IsSalted()) return false;
+
+    auto const algo = password_hash_->HashAlgo();
+    UpdatePassword(password, algo);
+    return true;
+  }
+
   /// @throw AuthException if unable to set the password.
-  void UpdatePassword(const std::optional<std::string> &password = std::nullopt);
+  void UpdatePassword(const std::optional<std::string> &password = {},
+                      std::optional<PasswordHashAlgorithm> algo_override = std::nullopt);
 
   void SetRole(const Role &role);
 
@@ -358,6 +371,10 @@ class User final {
 #ifdef MG_ENTERPRISE
   FineGrainedAccessPermissions GetFineGrainedAccessLabelPermissions() const;
   FineGrainedAccessPermissions GetFineGrainedAccessEdgeTypePermissions() const;
+  FineGrainedAccessPermissions GetUserFineGrainedAccessLabelPermissions() const;
+  FineGrainedAccessPermissions GetUserFineGrainedAccessEdgeTypePermissions() const;
+  FineGrainedAccessPermissions GetRoleFineGrainedAccessLabelPermissions() const;
+  FineGrainedAccessPermissions GetRoleFineGrainedAccessEdgeTypePermissions() const;
   const FineGrainedAccessHandler &fine_grained_access_handler() const;
   FineGrainedAccessHandler &fine_grained_access_handler();
 #endif
@@ -382,7 +399,7 @@ class User final {
 
  private:
   std::string username_;
-  std::string password_hash_;
+  std::optional<HashedPassword> password_hash_;
   Permissions permissions_;
 #ifdef MG_ENTERPRISE
   FineGrainedAccessHandler fine_grained_access_handler_;

src/auth/replication_handlers.cpp

@@ -0,0 +1,190 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#include "auth/replication_handlers.hpp"
+
+#include "auth/auth.hpp"
+#include "auth/rpc.hpp"
+#include "license/license.hpp"
+
+namespace memgraph::auth {
+
+void LogWrongMain(const std::optional<utils::UUID> &current_main_uuid, const utils::UUID &main_req_id,
+                  std::string_view rpc_req) {
+  spdlog::error(fmt::format("Received {} with main_id: {} != current_main_uuid: {}", rpc_req, std::string(main_req_id),
+                            current_main_uuid.has_value() ? std::string(current_main_uuid.value()) : ""));
+}
+
+#ifdef MG_ENTERPRISE
+void UpdateAuthDataHandler(memgraph::system::ReplicaHandlerAccessToState &system_state_access,
+                           const std::optional<utils::UUID> &current_main_uuid, auth::SynchedAuth &auth,
+                           slk::Reader *req_reader, slk::Builder *res_builder) {
+  replication::UpdateAuthDataReq req;
+  memgraph::slk::Load(&req, req_reader);
+
+  using memgraph::replication::UpdateAuthDataRes;
+  UpdateAuthDataRes res(false);
+
+  if (!current_main_uuid.has_value() || req.main_uuid != current_main_uuid) [[unlikely]] {
+    LogWrongMain(current_main_uuid, req.main_uuid, replication::UpdateAuthDataReq::kType.name);
+    memgraph::slk::Save(res, res_builder);
+    return;
+  }
+
+  // Note: No need to check epoch, recovery mechanism is done by a full uptodate snapshot
+  //       of the set of databases. Hence no history exists to maintain regarding epoch change.
+  //       If MAIN has changed we need to check this new group_timestamp is consistent with
+  //       what we have so far.
+
+  if (req.expected_group_timestamp != system_state_access.LastCommitedTS()) {
+    spdlog::debug("UpdateAuthDataHandler: bad expected timestamp {},{}", req.expected_group_timestamp,
+                  system_state_access.LastCommitedTS());
+    memgraph::slk::Save(res, res_builder);
+    return;
+  }
+
+  try {
+    // Update
+    if (req.user) auth->SaveUser(*req.user);
+    if (req.role) auth->SaveRole(*req.role);
+    // Success
+    system_state_access.SetLastCommitedTS(req.new_group_timestamp);
+    res = UpdateAuthDataRes(true);
+    spdlog::debug("UpdateAuthDataHandler: SUCCESS updated LCTS to {}", req.new_group_timestamp);
+  } catch (const auth::AuthException & /* not used */) {
+    // Failure
+  }
+
+  memgraph::slk::Save(res, res_builder);
+}
+
+void DropAuthDataHandler(memgraph::system::ReplicaHandlerAccessToState &system_state_access,
+                         const std::optional<utils::UUID> &current_main_uuid, auth::SynchedAuth &auth,
+                         slk::Reader *req_reader, slk::Builder *res_builder) {
+  replication::DropAuthDataReq req;
+  memgraph::slk::Load(&req, req_reader);
+
+  using memgraph::replication::DropAuthDataRes;
+  DropAuthDataRes res(false);
+
+  if (!current_main_uuid.has_value() || req.main_uuid != current_main_uuid) [[unlikely]] {
+    LogWrongMain(current_main_uuid, req.main_uuid, replication::DropAuthDataRes::kType.name);
+    memgraph::slk::Save(res, res_builder);
+    return;
+  }
+
+  // Note: No need to check epoch, recovery mechanism is done by a full uptodate snapshot
+  //       of the set of databases. Hence no history exists to maintain regarding epoch change.
+  //       If MAIN has changed we need to check this new group_timestamp is consistent with
+  //       what we have so far.
+
+  if (req.expected_group_timestamp != system_state_access.LastCommitedTS()) {
+    spdlog::debug("DropAuthDataHandler: bad expected timestamp {},{}", req.expected_group_timestamp,
+                  system_state_access.LastCommitedTS());
+    memgraph::slk::Save(res, res_builder);
+    return;
+  }
+
+  try {
+    // Remove
+    switch (req.type) {
+      case replication::DropAuthDataReq::DataType::USER:
+        auth->RemoveUser(req.name);
+        break;
+      case replication::DropAuthDataReq::DataType::ROLE:
+        auth->RemoveRole(req.name);
+        break;
+    }
+    // Success
+    system_state_access.SetLastCommitedTS(req.new_group_timestamp);
+    res = DropAuthDataRes(true);
+    spdlog::debug("DropAuthDataHandler: SUCCESS updated LCTS to {}", req.new_group_timestamp);
+  } catch (const auth::AuthException & /* not used */) {
+    // Failure
+  }
+
+  memgraph::slk::Save(res, res_builder);
+}
+
+bool SystemRecoveryHandler(auth::SynchedAuth &auth, auth::Auth::Config auth_config,
+                           const std::vector<auth::User> &users, const std::vector<auth::Role> &roles) {
+  return auth.WithLock([&](auto &locked_auth) {
+    // Update config
+    locked_auth.SetConfig(std::move(auth_config));
+    // Get all current users
+    auto old_users = locked_auth.AllUsernames();
+    // Save incoming users
+    for (const auto &user : users) {
+      // Missing users
+      try {
+        locked_auth.SaveUser(user);
+      } catch (const auth::AuthException &) {
+        spdlog::debug("SystemRecoveryHandler: Failed to save user");
+        return false;
+      }
+      const auto it = std::find(old_users.begin(), old_users.end(), user.username());
+      if (it != old_users.end()) old_users.erase(it);
+    }
+    // Delete all the leftover users
+    for (const auto &user : old_users) {
+      if (!locked_auth.RemoveUser(user)) {
+        spdlog::debug("SystemRecoveryHandler: Failed to remove user \"{}\".", user);
+        return false;
+      }
+    }
+
+    // Roles are only supported with a license
+    if (license::global_license_checker.IsEnterpriseValidFast()) {
+      // Get all current roles
+      auto old_roles = locked_auth.AllRolenames();
+      // Save incoming users
+      for (const auto &role : roles) {
+        // Missing users
+        try {
+          locked_auth.SaveRole(role);
+        } catch (const auth::AuthException &) {
+          spdlog::debug("SystemRecoveryHandler: Failed to save user");
+          return false;
+        }
+        const auto it = std::find(old_roles.begin(), old_roles.end(), role.rolename());
+        if (it != old_roles.end()) old_roles.erase(it);
+      }
+      // Delete all the leftover users
+      for (const auto &role : old_roles) {
+        if (!locked_auth.RemoveRole(role)) {
+          spdlog::debug("SystemRecoveryHandler: Failed to remove user \"{}\".", role);
+          return false;
+        }
+      }
+    }
+
+    // Success
+    return true;
+  });
+}
+
+void Register(replication::RoleReplicaData const &data, system::ReplicaHandlerAccessToState &system_state_access,
+              auth::SynchedAuth &auth) {
+  // NOTE: Register even without license as the user could add a license at run-time
+  data.server->rpc_server_.Register<replication::UpdateAuthDataRpc>(
+      [&data, system_state_access, &auth](auto *req_reader, auto *res_builder) mutable {
+        spdlog::debug("Received UpdateAuthDataRpc");
+        UpdateAuthDataHandler(system_state_access, data.uuid_, auth, req_reader, res_builder);
+      });
+  data.server->rpc_server_.Register<replication::DropAuthDataRpc>(
+      [&data, system_state_access, &auth](auto *req_reader, auto *res_builder) mutable {
+        spdlog::debug("Received DropAuthDataRpc");
+        DropAuthDataHandler(system_state_access, data.uuid_, auth, req_reader, res_builder);
+      });
+}
+#endif
+
+}  // namespace memgraph::auth

src/auth/replication_handlers.hpp

@@ -0,0 +1,37 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include "auth/auth.hpp"
+#include "replication/state.hpp"
+#include "slk/streams.hpp"
+#include "system/state.hpp"
+
+namespace memgraph::auth {
+
+void LogWrongMain(const std::optional<utils::UUID> &current_main_uuid, const utils::UUID &main_req_id,
+                  std::string_view rpc_req);
+
+#ifdef MG_ENTERPRISE
+void UpdateAuthDataHandler(system::ReplicaHandlerAccessToState &system_state_access,
+                           const std::optional<utils::UUID> &current_main_uuid, auth::SynchedAuth &auth,
+                           slk::Reader *req_reader, slk::Builder *res_builder);
+void DropAuthDataHandler(system::ReplicaHandlerAccessToState &system_state_access,
+                         const std::optional<utils::UUID> &current_main_uuid, auth::SynchedAuth &auth,
+                         slk::Reader *req_reader, slk::Builder *res_builder);
+
+bool SystemRecoveryHandler(auth::SynchedAuth &auth, auth::Auth::Config auth_config,
+                           const std::vector<auth::User> &users, const std::vector<auth::Role> &roles);
+void Register(replication::RoleReplicaData const &data, system::ReplicaHandlerAccessToState &system_state_access,
+              auth::SynchedAuth &auth);
+#endif
+}  // namespace memgraph::auth

src/auth/rpc.cpp

@@ -0,0 +1,182 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#include "auth/rpc.hpp"
+
+#include <json/json.hpp>
+#include "auth/auth.hpp"
+#include "slk/serialization.hpp"
+#include "slk/streams.hpp"
+#include "utils/enum.hpp"
+
+namespace memgraph::slk {
+
+// Serialize code for auth::Role
+void Save(const auth::Role &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self.Serialize().dump(), builder);
+}
+namespace {
+auth::Role LoadAuthRole(memgraph::slk::Reader *reader) {
+  std::string tmp;
+  memgraph::slk::Load(&tmp, reader);
+  const auto json = nlohmann::json::parse(tmp);
+  return memgraph::auth::Role::Deserialize(json);
+}
+}  // namespace
+// Deserialize code for auth::Role
+void Load(auth::Role *self, memgraph::slk::Reader *reader) { *self = LoadAuthRole(reader); }
+// Special case for optional<Role>
+template <>
+inline void Load<auth::Role>(std::optional<auth::Role> *obj, Reader *reader) {
+  bool exists = false;
+  Load(&exists, reader);
+  if (exists) {
+    obj->emplace(LoadAuthRole(reader));
+  } else {
+    *obj = std::nullopt;
+  }
+}
+
+// Serialize code for auth::User
+void Save(const auth::User &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self.Serialize().dump(), builder);
+  std::optional<auth::Role> role{};
+  if (const auto *role_ptr = self.role(); role_ptr) {
+    role.emplace(*role_ptr);
+  }
+  memgraph::slk::Save(role, builder);
+}
+// Deserialize code for auth::User
+void Load(auth::User *self, memgraph::slk::Reader *reader) {
+  std::string tmp;
+  memgraph::slk::Load(&tmp, reader);
+  const auto json = nlohmann::json::parse(tmp);
+  *self = memgraph::auth::User::Deserialize(json);
+  std::optional<auth::Role> role{};
+  memgraph::slk::Load(&role, reader);
+  if (role)
+    self->SetRole(*role);
+  else
+    self->ClearRole();
+}
+
+// Serialize code for auth::Auth::Config
+void Save(const auth::Auth::Config &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self.name_regex_str, builder);
+  memgraph::slk::Save(self.password_regex_str, builder);
+  memgraph::slk::Save(self.password_permit_null, builder);
+}
+// Deserialize code for auth::Auth::Config
+void Load(auth::Auth::Config *self, memgraph::slk::Reader *reader) {
+  std::string name_regex_str{};
+  std::string password_regex_str{};
+  bool password_permit_null{};
+
+  memgraph::slk::Load(&name_regex_str, reader);
+  memgraph::slk::Load(&password_regex_str, reader);
+  memgraph::slk::Load(&password_permit_null, reader);
+
+  *self = auth::Auth::Config{std::move(name_regex_str), std::move(password_regex_str), password_permit_null};
+}
+
+// Serialize code for UpdateAuthDataReq
+void Save(const memgraph::replication::UpdateAuthDataReq &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self.main_uuid, builder);
+  memgraph::slk::Save(self.epoch_id, builder);
+  memgraph::slk::Save(self.expected_group_timestamp, builder);
+  memgraph::slk::Save(self.new_group_timestamp, builder);
+  memgraph::slk::Save(self.user, builder);
+  memgraph::slk::Save(self.role, builder);
+}
+void Load(memgraph::replication::UpdateAuthDataReq *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(&self->main_uuid, reader);
+  memgraph::slk::Load(&self->epoch_id, reader);
+  memgraph::slk::Load(&self->expected_group_timestamp, reader);
+  memgraph::slk::Load(&self->new_group_timestamp, reader);
+  memgraph::slk::Load(&self->user, reader);
+  memgraph::slk::Load(&self->role, reader);
+}
+
+// Serialize code for UpdateAuthDataRes
+void Save(const memgraph::replication::UpdateAuthDataRes &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self.success, builder);
+}
+void Load(memgraph::replication::UpdateAuthDataRes *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(&self->success, reader);
+}
+
+// Serialize code for DropAuthDataReq
+void Save(const memgraph::replication::DropAuthDataReq &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self.main_uuid, builder);
+  memgraph::slk::Save(self.epoch_id, builder);
+  memgraph::slk::Save(self.expected_group_timestamp, builder);
+  memgraph::slk::Save(self.new_group_timestamp, builder);
+  memgraph::slk::Save(utils::EnumToNum<2, uint8_t>(self.type), builder);
+  memgraph::slk::Save(self.name, builder);
+}
+void Load(memgraph::replication::DropAuthDataReq *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(&self->main_uuid, reader);
+  memgraph::slk::Load(&self->epoch_id, reader);
+  memgraph::slk::Load(&self->expected_group_timestamp, reader);
+  memgraph::slk::Load(&self->new_group_timestamp, reader);
+  uint8_t type_tmp = 0;
+  memgraph::slk::Load(&type_tmp, reader);
+  if (!utils::NumToEnum<2>(type_tmp, self->type)) {
+    throw SlkReaderException("Unexpected result line:{}!", __LINE__);
+  }
+  memgraph::slk::Load(&self->name, reader);
+}
+
+// Serialize code for DropAuthDataRes
+void Save(const memgraph::replication::DropAuthDataRes &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self.success, builder);
+}
+void Load(memgraph::replication::DropAuthDataRes *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(&self->success, reader);
+}
+
+}  // namespace memgraph::slk
+
+namespace memgraph::replication {
+
+constexpr utils::TypeInfo UpdateAuthDataReq::kType{utils::TypeId::REP_UPDATE_AUTH_DATA_REQ, "UpdateAuthDataReq",
+                                                   nullptr};
+
+constexpr utils::TypeInfo UpdateAuthDataRes::kType{utils::TypeId::REP_UPDATE_AUTH_DATA_RES, "UpdateAuthDataRes",
+                                                   nullptr};
+
+constexpr utils::TypeInfo DropAuthDataReq::kType{utils::TypeId::REP_DROP_AUTH_DATA_REQ, "DropAuthDataReq", nullptr};
+
+constexpr utils::TypeInfo DropAuthDataRes::kType{utils::TypeId::REP_DROP_AUTH_DATA_RES, "DropAuthDataRes", nullptr};
+
+void UpdateAuthDataReq::Save(const UpdateAuthDataReq &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self, builder);
+}
+void UpdateAuthDataReq::Load(UpdateAuthDataReq *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(self, reader);
+}
+void UpdateAuthDataRes::Save(const UpdateAuthDataRes &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self, builder);
+}
+void UpdateAuthDataRes::Load(UpdateAuthDataRes *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(self, reader);
+}
+
+void DropAuthDataReq::Save(const DropAuthDataReq &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self, builder);
+}
+void DropAuthDataReq::Load(DropAuthDataReq *self, memgraph::slk::Reader *reader) { memgraph::slk::Load(self, reader); }
+void DropAuthDataRes::Save(const DropAuthDataRes &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self, builder);
+}
+void DropAuthDataRes::Load(DropAuthDataRes *self, memgraph::slk::Reader *reader) { memgraph::slk::Load(self, reader); }
+
+}  // namespace memgraph::replication

src/auth/rpc.hpp

@@ -0,0 +1,127 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <optional>
+
+#include "auth/auth.hpp"
+#include "auth/models.hpp"
+#include "rpc/messages.hpp"
+#include "slk/streams.hpp"
+
+namespace memgraph::replication {
+
+struct UpdateAuthDataReq {
+  static const utils::TypeInfo kType;
+  static const utils::TypeInfo &GetTypeInfo() { return kType; }
+
+  static void Load(UpdateAuthDataReq *self, memgraph::slk::Reader *reader);
+  static void Save(const UpdateAuthDataReq &self, memgraph::slk::Builder *builder);
+  UpdateAuthDataReq() = default;
+  UpdateAuthDataReq(const utils::UUID &main_uuid, std::string epoch_id, uint64_t expected_ts, uint64_t new_ts,
+                    auth::User user)
+      : main_uuid(main_uuid),
+        epoch_id{std::move(epoch_id)},
+        expected_group_timestamp{expected_ts},
+        new_group_timestamp{new_ts},
+        user{std::move(user)} {}
+  UpdateAuthDataReq(const utils::UUID &main_uuid, std::string epoch_id, uint64_t expected_ts, uint64_t new_ts,
+                    auth::Role role)
+      : main_uuid(main_uuid),
+        epoch_id{std::move(epoch_id)},
+        expected_group_timestamp{expected_ts},
+        new_group_timestamp{new_ts},
+        role{std::move(role)} {}
+
+  utils::UUID main_uuid;
+  std::string epoch_id;
+  uint64_t expected_group_timestamp;
+  uint64_t new_group_timestamp;
+  std::optional<auth::User> user;
+  std::optional<auth::Role> role;
+};
+
+struct UpdateAuthDataRes {
+  static const utils::TypeInfo kType;
+  static const utils::TypeInfo &GetTypeInfo() { return kType; }
+
+  static void Load(UpdateAuthDataRes *self, memgraph::slk::Reader *reader);
+  static void Save(const UpdateAuthDataRes &self, memgraph::slk::Builder *builder);
+  UpdateAuthDataRes() = default;
+  explicit UpdateAuthDataRes(bool success) : success{success} {}
+
+  bool success;
+};
+
+using UpdateAuthDataRpc = rpc::RequestResponse<UpdateAuthDataReq, UpdateAuthDataRes>;
+
+struct DropAuthDataReq {
+  static const utils::TypeInfo kType;
+  static const utils::TypeInfo &GetTypeInfo() { return kType; }
+
+  static void Load(DropAuthDataReq *self, memgraph::slk::Reader *reader);
+  static void Save(const DropAuthDataReq &self, memgraph::slk::Builder *builder);
+  DropAuthDataReq() = default;
+
+  enum class DataType { USER, ROLE };
+
+  DropAuthDataReq(const utils::UUID &main_uuid, std::string epoch_id, uint64_t expected_ts, uint64_t new_ts,
+                  DataType type, std::string_view name)
+      : main_uuid(main_uuid),
+        epoch_id{std::move(epoch_id)},
+        expected_group_timestamp{expected_ts},
+        new_group_timestamp{new_ts},
+        type{type},
+        name{name} {}
+
+  utils::UUID main_uuid;
+  std::string epoch_id;
+  uint64_t expected_group_timestamp;
+  uint64_t new_group_timestamp;
+  DataType type;
+  std::string name;
+};
+
+struct DropAuthDataRes {
+  static const utils::TypeInfo kType;
+  static const utils::TypeInfo &GetTypeInfo() { return kType; }
+
+  static void Load(DropAuthDataRes *self, memgraph::slk::Reader *reader);
+  static void Save(const DropAuthDataRes &self, memgraph::slk::Builder *builder);
+  DropAuthDataRes() = default;
+  explicit DropAuthDataRes(bool success) : success{success} {}
+
+  bool success;
+};
+
+using DropAuthDataRpc = rpc::RequestResponse<DropAuthDataReq, DropAuthDataRes>;
+
+}  // namespace memgraph::replication
+
+namespace memgraph::slk {
+
+void Save(const auth::Role &self, memgraph::slk::Builder *builder);
+void Load(auth::Role *self, memgraph::slk::Reader *reader);
+void Save(const auth::User &self, memgraph::slk::Builder *builder);
+void Load(auth::User *self, memgraph::slk::Reader *reader);
+void Save(const auth::Auth::Config &self, memgraph::slk::Builder *builder);
+void Load(auth::Auth::Config *self, memgraph::slk::Reader *reader);
+
+void Save(const memgraph::replication::UpdateAuthDataRes &self, memgraph::slk::Builder *builder);
+void Load(memgraph::replication::UpdateAuthDataRes *self, memgraph::slk::Reader *reader);
+void Save(const memgraph::replication::UpdateAuthDataReq & /*self*/, memgraph::slk::Builder * /*builder*/);
+void Load(memgraph::replication::UpdateAuthDataReq * /*self*/, memgraph::slk::Reader * /*reader*/);
+void Save(const memgraph::replication::DropAuthDataRes &self, memgraph::slk::Builder *builder);
+void Load(memgraph::replication::DropAuthDataRes *self, memgraph::slk::Reader *reader);
+void Save(const memgraph::replication::DropAuthDataReq & /*self*/, memgraph::slk::Builder * /*builder*/);
+void Load(memgraph::replication::DropAuthDataReq * /*self*/, memgraph::slk::Reader * /*reader*/);
+}  // namespace memgraph::slk

src/communication/websocket/auth.hpp

@@ -1,4 +1,4 @@
-// Copyright 2022 Memgraph Ltd.
+// Copyright 2024 Memgraph Ltd.
 //
 // Use of this software is governed by the Business Source License
 // included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
@@ -14,8 +14,6 @@
 #include <string>
 
 #include "auth/auth.hpp"
-#include "utils/spin_lock.hpp"
-#include "utils/synchronized.hpp"
 
 namespace memgraph::communication::websocket {
 
@@ -30,7 +28,7 @@ class AuthenticationInterface {
 
 class SafeAuth : public AuthenticationInterface {
  public:
-  explicit SafeAuth(utils::Synchronized<auth::Auth, utils::WritePrioritizedRWLock> *auth) : auth_{auth} {}
+  explicit SafeAuth(auth::SynchedAuth *auth) : auth_{auth} {}
 
   bool Authenticate(const std::string &username, const std::string &password) const override;
 
@@ -39,6 +37,6 @@ class SafeAuth : public AuthenticationInterface {
   bool HasAnyUsers() const override;
 
  private:
-  utils::Synchronized<auth::Auth, utils::WritePrioritizedRWLock> *auth_;
+  auth::SynchedAuth *auth_;
 };
 }  // namespace memgraph::communication::websocket

src/coordination/CMakeLists.txt

@@ -7,19 +7,36 @@ target_sources(mg-coordination
         include/coordination/coordinator_rpc.hpp
         include/coordination/coordinator_server.hpp
         include/coordination/coordinator_config.hpp
-        include/coordination/coordinator_entity_info.hpp
         include/coordination/coordinator_exceptions.hpp
         include/coordination/coordinator_slk.hpp
+        include/coordination/coordinator_instance.hpp
+        include/coordination/coordinator_handlers.hpp
         include/coordination/constants.hpp
+        include/coordination/instance_status.hpp
+        include/coordination/replication_instance.hpp
+        include/coordination/raft_state.hpp
+        include/coordination/rpc_errors.hpp
+
+        include/nuraft/coordinator_log_store.hpp
+        include/nuraft/coordinator_state_machine.hpp
+        include/nuraft/coordinator_state_manager.hpp
 
         PRIVATE
         coordinator_client.cpp
         coordinator_state.cpp
         coordinator_rpc.cpp
         coordinator_server.cpp
+        coordinator_handlers.cpp
+        coordinator_instance.cpp
+        replication_instance.cpp
+        raft_state.cpp
+
+        coordinator_log_store.cpp
+        coordinator_state_machine.cpp
+        coordinator_state_manager.cpp
 )
 target_include_directories(mg-coordination PUBLIC include)
 
 target_link_libraries(mg-coordination
-    PUBLIC mg::utils mg::rpc mg::slk mg::io mg::repl_coord_glue
+    PUBLIC mg::utils mg::rpc mg::slk mg::io mg::repl_coord_glue lib::rangev3 nuraft mg-replication_handler
 )

src/coordination/coordinator_client.cpp

@@ -9,6 +9,7 @@
 // by the Apache License, Version 2.0, included in the file
 // licenses/APL.txt.
 
+#include "utils/uuid.hpp"
 #ifdef MG_ENTERPRISE
 
 #include "coordination/coordinator_client.hpp"
@@ -16,95 +17,156 @@
 #include "coordination/coordinator_config.hpp"
 #include "coordination/coordinator_rpc.hpp"
 #include "replication_coordination_glue/messages.hpp"
+#include "utils/result.hpp"
 
 namespace memgraph::coordination {
 
 namespace {
-auto CreateClientContext(const memgraph::coordination::CoordinatorClientConfig &config)
+auto CreateClientContext(memgraph::coordination::CoordinatorClientConfig const &config)
     -> communication::ClientContext {
   return (config.ssl) ? communication::ClientContext{config.ssl->key_file, config.ssl->cert_file}
                       : communication::ClientContext{};
 }
 }  // namespace
 
-CoordinatorClient::CoordinatorClient(const CoordinatorClientConfig &config)
+CoordinatorClient::CoordinatorClient(CoordinatorInstance *coord_instance, CoordinatorClientConfig config,
+                                     HealthCheckCallback succ_cb, HealthCheckCallback fail_cb)
     : rpc_context_{CreateClientContext(config)},
       rpc_client_{io::network::Endpoint(io::network::Endpoint::needs_resolving, config.ip_address, config.port),
                   &rpc_context_},
-      config_{config} {}
+      config_{std::move(config)},
+      coord_instance_{coord_instance},
+      succ_cb_{std::move(succ_cb)},
+      fail_cb_{std::move(fail_cb)} {}
 
-CoordinatorClient::~CoordinatorClient() {
-  auto exit_job = utils::OnScopeExit([&] {
-    StopFrequentCheck();
-    thread_pool_.Shutdown();
-  });
-  const auto endpoint = rpc_client_.Endpoint();
-  // Logging can throw
-  spdlog::trace("Closing replication client on {}:{}", endpoint.address, endpoint.port);
+auto CoordinatorClient::InstanceName() const -> std::string { return config_.instance_name; }
+auto CoordinatorClient::SocketAddress() const -> std::string { return rpc_client_.Endpoint().SocketAddress(); }
+
+auto CoordinatorClient::InstanceDownTimeoutSec() const -> std::chrono::seconds {
+  return config_.instance_down_timeout_sec;
+}
+
+auto CoordinatorClient::InstanceGetUUIDFrequencySec() const -> std::chrono::seconds {
+  return config_.instance_get_uuid_frequency_sec;
 }
 
 void CoordinatorClient::StartFrequentCheck() {
-  MG_ASSERT(config_.health_check_frequency_sec > std::chrono::seconds(0),
+  if (instance_checker_.IsRunning()) {
+    return;
+  }
+
+  MG_ASSERT(config_.instance_health_check_frequency_sec > std::chrono::seconds(0),
             "Health check frequency must be greater than 0");
-  replica_checker_.Run(
-      "Coord checker", config_.health_check_frequency_sec,
-      [last_response_time = &last_response_time_, rpc_client = &rpc_client_] {
+
+  instance_checker_.Run(
+      config_.instance_name, config_.instance_health_check_frequency_sec,
+      [this, instance_name = config_.instance_name] {
         try {
-          {
-            auto stream{rpc_client->Stream<memgraph::replication_coordination_glue::FrequentHeartbeatRpc>()};
+          spdlog::trace("Sending frequent heartbeat to machine {} on {}", instance_name,
+                        rpc_client_.Endpoint().SocketAddress());
+          {  // NOTE: This is intentionally scoped so that stream lock could get released.
+            auto stream{rpc_client_.Stream<memgraph::replication_coordination_glue::FrequentHeartbeatRpc>()};
             stream.AwaitResponse();
-            last_response_time->store(std::chrono::system_clock::now(), std::memory_order_acq_rel);
           }
-        } catch (const rpc::RpcFailedException &) {
-          // Nothing to do...wait for a reconnect
+          succ_cb_(coord_instance_, instance_name);
+        } catch (rpc::RpcFailedException const &) {
+          fail_cb_(coord_instance_, instance_name);
         }
       });
 }
 
-void CoordinatorClient::StopFrequentCheck() { replica_checker_.Stop(); }
+void CoordinatorClient::StopFrequentCheck() { instance_checker_.Stop(); }
+void CoordinatorClient::PauseFrequentCheck() { instance_checker_.Pause(); }
+void CoordinatorClient::ResumeFrequentCheck() { instance_checker_.Resume(); }
 
-bool CoordinatorClient::DoHealthCheck() const {
-  auto current_time = std::chrono::system_clock::now();
-  auto duration = std::chrono::duration_cast<std::chrono::seconds>(current_time -
-                                                                   last_response_time_.load(std::memory_order_acquire));
-  return duration.count() <= alive_response_time_difference_sec_;
+auto CoordinatorClient::SetCallbacks(HealthCheckCallback succ_cb, HealthCheckCallback fail_cb) -> void {
+  succ_cb_ = std::move(succ_cb);
+  fail_cb_ = std::move(fail_cb);
 }
 
-auto CoordinatorClient::InstanceName() const -> std::string_view { return config_.instance_name; }
-auto CoordinatorClient::Endpoint() const -> io::network::Endpoint const & { return rpc_client_.Endpoint(); }
-auto CoordinatorClient::Config() const -> CoordinatorClientConfig const & { return config_; }
+auto CoordinatorClient::ReplicationClientInfo() const -> ReplClientInfo { return config_.replication_client_info; }
 
-auto CoordinatorClient::ReplicationClientInfo() const -> CoordinatorClientConfig::ReplicationClientInfo const & {
-  MG_ASSERT(config_.replication_client_info.has_value(), "No ReplicationClientInfo for MAIN instance!");
-  return *config_.replication_client_info;
-}
-
-////// AF design choice
-auto CoordinatorClient::ReplicationClientInfo() -> std::optional<CoordinatorClientConfig::ReplicationClientInfo> & {
-  MG_ASSERT(config_.replication_client_info.has_value(), "No ReplicationClientInfo for MAIN instance!");
-  return config_.replication_client_info;
-}
-
-void CoordinatorClient::UpdateTimeCheck(const std::chrono::system_clock::time_point &last_checked_time) {
-  last_response_time_.store(last_checked_time, std::memory_order_acq_rel);
-}
-
-auto CoordinatorClient::GetLastTimeResponse() -> std::chrono::system_clock::time_point { return last_response_time_; }
-
-auto CoordinatorClient::SendPromoteReplicaToMainRpc(
-    std::vector<CoordinatorClientConfig::ReplicationClientInfo> replication_clients_info) const -> bool {
+auto CoordinatorClient::SendPromoteReplicaToMainRpc(const utils::UUID &uuid,
+                                                    ReplicationClientsInfo replication_clients_info) const -> bool {
   try {
-    {
-      auto stream{rpc_client_.Stream<PromoteReplicaToMainRpc>(std::move(replication_clients_info))};
-      if (!stream.AwaitResponse().success) {
-        spdlog::error("Failed to perform failover!");
-        return false;
-      }
-      spdlog::info("Sent failover RPC from coordinator to new main!");
-      return true;
+    auto stream{rpc_client_.Stream<PromoteReplicaToMainRpc>(uuid, std::move(replication_clients_info))};
+    if (!stream.AwaitResponse().success) {
+      spdlog::error("Failed to receive successful PromoteReplicaToMainRpc response!");
+      return false;
     }
+    return true;
+  } catch (rpc::RpcFailedException const &) {
+    spdlog::error("RPC error occurred while sending PromoteReplicaToMainRpc!");
+  }
+  return false;
+}
+
+auto CoordinatorClient::DemoteToReplica() const -> bool {
+  auto const &instance_name = config_.instance_name;
+  try {
+    auto stream{rpc_client_.Stream<DemoteMainToReplicaRpc>(config_.replication_client_info)};
+    if (!stream.AwaitResponse().success) {
+      spdlog::error("Failed to receive successful RPC response for setting instance {} to replica!", instance_name);
+      return false;
+    }
+    spdlog::info("Sent request RPC from coordinator to instance to set it as replica!");
+    return true;
+  } catch (rpc::RpcFailedException const &) {
+    spdlog::error("Failed to set instance {} to replica!", instance_name);
+  }
+  return false;
+}
+
+auto CoordinatorClient::SendSwapMainUUIDRpc(const utils::UUID &uuid) const -> bool {
+  try {
+    auto stream{rpc_client_.Stream<replication_coordination_glue::SwapMainUUIDRpc>(uuid)};
+    if (!stream.AwaitResponse().success) {
+      spdlog::error("Failed to receive successful RPC swapping of uuid response!");
+      return false;
+    }
+    return true;
   } catch (const rpc::RpcFailedException &) {
-    spdlog::error("Failed to send failover RPC from coordinator to new main!");
+    spdlog::error("RPC error occurred while sending swapping uuid RPC!");
+  }
+  return false;
+}
+
+auto CoordinatorClient::SendUnregisterReplicaRpc(std::string const &instance_name) const -> bool {
+  try {
+    auto stream{rpc_client_.Stream<UnregisterReplicaRpc>(instance_name)};
+    if (!stream.AwaitResponse().success) {
+      spdlog::error("Failed to receive successful RPC response for unregistering replica!");
+      return false;
+    }
+    return true;
+  } catch (rpc::RpcFailedException const &) {
+    spdlog::error("Failed to unregister replica!");
+  }
+  return false;
+}
+
+auto CoordinatorClient::SendGetInstanceUUIDRpc() const
+    -> utils::BasicResult<GetInstanceUUIDError, std::optional<utils::UUID>> {
+  try {
+    auto stream{rpc_client_.Stream<GetInstanceUUIDRpc>()};
+    auto res = stream.AwaitResponse();
+    return res.uuid;
+  } catch (const rpc::RpcFailedException &) {
+    spdlog::error("RPC error occured while sending GetInstance UUID RPC");
+    return GetInstanceUUIDError::RPC_EXCEPTION;
+  }
+}
+
+auto CoordinatorClient::SendEnableWritingOnMainRpc() const -> bool {
+  try {
+    auto stream{rpc_client_.Stream<EnableWritingOnMainRpc>()};
+    if (!stream.AwaitResponse().success) {
+      spdlog::error("Failed to receive successful RPC response for enabling writing on main!");
+      return false;
+    }
+    return true;
+  } catch (rpc::RpcFailedException const &) {
+    spdlog::error("Failed to enable writing on main!");
   }
   return false;
 }

src/coordination/coordinator_handlers.cpp

@@ -0,0 +1,218 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#ifdef MG_ENTERPRISE
+#include "coordination/coordinator_handlers.hpp"
+
+#include <range/v3/view.hpp>
+
+#include "coordination/coordinator_rpc.hpp"
+#include "coordination/include/coordination/coordinator_server.hpp"
+#include "replication/state.hpp"
+
+namespace memgraph::dbms {
+
+void CoordinatorHandlers::Register(memgraph::coordination::CoordinatorServer &server,
+                                   replication::ReplicationHandler &replication_handler) {
+  server.Register<coordination::PromoteReplicaToMainRpc>(
+      [&](slk::Reader *req_reader, slk::Builder *res_builder) -> void {
+        spdlog::info("Received PromoteReplicaToMainRpc");
+        CoordinatorHandlers::PromoteReplicaToMainHandler(replication_handler, req_reader, res_builder);
+      });
+
+  server.Register<coordination::DemoteMainToReplicaRpc>(
+      [&replication_handler](slk::Reader *req_reader, slk::Builder *res_builder) -> void {
+        spdlog::info("Received DemoteMainToReplicaRpc from coordinator server");
+        CoordinatorHandlers::DemoteMainToReplicaHandler(replication_handler, req_reader, res_builder);
+      });
+
+  server.Register<replication_coordination_glue::SwapMainUUIDRpc>(
+      [&replication_handler](slk::Reader *req_reader, slk::Builder *res_builder) -> void {
+        spdlog::info("Received SwapMainUUIDRPC on coordinator server");
+        CoordinatorHandlers::SwapMainUUIDHandler(replication_handler, req_reader, res_builder);
+      });
+
+  server.Register<coordination::UnregisterReplicaRpc>(
+      [&replication_handler](slk::Reader *req_reader, slk::Builder *res_builder) -> void {
+        spdlog::info("Received UnregisterReplicaRpc on coordinator server");
+        CoordinatorHandlers::UnregisterReplicaHandler(replication_handler, req_reader, res_builder);
+      });
+
+  server.Register<coordination::EnableWritingOnMainRpc>(
+      [&replication_handler](slk::Reader *req_reader, slk::Builder *res_builder) -> void {
+        spdlog::info("Received EnableWritingOnMainRpc on coordinator server");
+        CoordinatorHandlers::EnableWritingOnMainHandler(replication_handler, req_reader, res_builder);
+      });
+
+  server.Register<coordination::GetInstanceUUIDRpc>(
+      [&replication_handler](slk::Reader *req_reader, slk::Builder *res_builder) -> void {
+        spdlog::info("Received GetInstanceUUIDRpc on coordinator server");
+        CoordinatorHandlers::GetInstanceUUIDHandler(replication_handler, req_reader, res_builder);
+      });
+}
+
+void CoordinatorHandlers::SwapMainUUIDHandler(replication::ReplicationHandler &replication_handler,
+                                              slk::Reader *req_reader, slk::Builder *res_builder) {
+  if (!replication_handler.IsReplica()) {
+    spdlog::error("Setting main uuid must be performed on replica.");
+    slk::Save(replication_coordination_glue::SwapMainUUIDRes{false}, res_builder);
+    return;
+  }
+
+  replication_coordination_glue::SwapMainUUIDReq req;
+  slk::Load(&req, req_reader);
+  spdlog::info(fmt::format("Set replica data UUID  to main uuid {}", std::string(req.uuid)));
+  std::get<memgraph::replication::RoleReplicaData>(replication_handler.GetReplState().ReplicationData()).uuid_ =
+      req.uuid;
+
+  slk::Save(replication_coordination_glue::SwapMainUUIDRes{true}, res_builder);
+}
+
+void CoordinatorHandlers::DemoteMainToReplicaHandler(replication::ReplicationHandler &replication_handler,
+                                                     slk::Reader *req_reader, slk::Builder *res_builder) {
+  spdlog::info("Executing DemoteMainToReplicaHandler");
+
+  coordination::DemoteMainToReplicaReq req;
+  slk::Load(&req, req_reader);
+
+  const replication::ReplicationServerConfig clients_config{
+      .ip_address = req.replication_client_info.replication_ip_address,
+      .port = req.replication_client_info.replication_port};
+
+  if (!replication_handler.SetReplicationRoleReplica(clients_config, std::nullopt)) {
+    spdlog::error("Demoting main to replica failed!");
+    slk::Save(coordination::DemoteMainToReplicaRes{false}, res_builder);
+    return;
+  }
+
+  slk::Save(coordination::DemoteMainToReplicaRes{true}, res_builder);
+}
+
+void CoordinatorHandlers::GetInstanceUUIDHandler(replication::ReplicationHandler &replication_handler,
+                                                 slk::Reader * /*req_reader*/, slk::Builder *res_builder) {
+  spdlog::info("Executing GetInstanceUUIDHandler");
+
+  slk::Save(coordination::GetInstanceUUIDRes{replication_handler.GetReplicaUUID()}, res_builder);
+}
+
+void CoordinatorHandlers::PromoteReplicaToMainHandler(replication::ReplicationHandler &replication_handler,
+                                                      slk::Reader *req_reader, slk::Builder *res_builder) {
+  if (!replication_handler.IsReplica()) {
+    spdlog::error("Failover must be performed on replica!");
+    slk::Save(coordination::PromoteReplicaToMainRes{false}, res_builder);
+    return;
+  }
+  coordination::PromoteReplicaToMainReq req;
+  slk::Load(&req, req_reader);
+
+  // This can fail because of disk. If it does, the cluster state could get inconsistent.
+  // We don't handle disk issues.
+  if (const bool success = replication_handler.DoReplicaToMainPromotion(req.main_uuid_); !success) {
+    spdlog::error("Promoting replica to main failed!");
+    slk::Save(coordination::PromoteReplicaToMainRes{false}, res_builder);
+    return;
+  }
+
+  auto const converter = [](const auto &repl_info_config) {
+    return replication::ReplicationClientConfig{
+        .name = repl_info_config.instance_name,
+        .mode = repl_info_config.replication_mode,
+        .ip_address = repl_info_config.replication_ip_address,
+        .port = repl_info_config.replication_port,
+    };
+  };
+
+  // registering replicas
+  for (auto const &config : req.replication_clients_info | ranges::views::transform(converter)) {
+    auto instance_client = replication_handler.RegisterReplica(config, false);
+    if (instance_client.HasError()) {
+      using enum memgraph::replication::RegisterReplicaError;
+      switch (instance_client.GetError()) {
+        // Can't happen, checked on the coordinator side
+        case memgraph::query::RegisterReplicaError::NAME_EXISTS:
+          spdlog::error("Replica with the same name already exists!");
+          slk::Save(coordination::PromoteReplicaToMainRes{false}, res_builder);
+          return;
+        // Can't happen, checked on the coordinator side
+        case memgraph::query::RegisterReplicaError::ENDPOINT_EXISTS:
+          spdlog::error("Replica with the same endpoint already exists!");
+          slk::Save(coordination::PromoteReplicaToMainRes{false}, res_builder);
+          return;
+        // We don't handle disk issues
+        case memgraph::query::RegisterReplicaError::COULD_NOT_BE_PERSISTED:
+          spdlog::error("Registered replica could not be persisted!");
+          slk::Save(coordination::PromoteReplicaToMainRes{false}, res_builder);
+          return;
+        case memgraph::query::RegisterReplicaError::ERROR_ACCEPTING_MAIN:
+          spdlog::error("Replica didn't accept change of main!");
+          slk::Save(coordination::PromoteReplicaToMainRes{false}, res_builder);
+          return;
+        case memgraph::query::RegisterReplicaError::CONNECTION_FAILED:
+          // Connection failure is not a fatal error
+          break;
+      }
+    }
+  }
+  spdlog::info("Promote replica to main was success {}", std::string(req.main_uuid_));
+  slk::Save(coordination::PromoteReplicaToMainRes{true}, res_builder);
+}
+
+void CoordinatorHandlers::UnregisterReplicaHandler(replication::ReplicationHandler &replication_handler,
+                                                   slk::Reader *req_reader, slk::Builder *res_builder) {
+  if (!replication_handler.IsMain()) {
+    spdlog::error("Unregistering replica must be performed on main.");
+    slk::Save(coordination::UnregisterReplicaRes{false}, res_builder);
+    return;
+  }
+
+  coordination::UnregisterReplicaReq req;
+  slk::Load(&req, req_reader);
+
+  auto res = replication_handler.UnregisterReplica(req.instance_name);
+  switch (res) {
+    using enum memgraph::query::UnregisterReplicaResult;
+    case SUCCESS:
+      slk::Save(coordination::UnregisterReplicaRes{true}, res_builder);
+      break;
+    case NOT_MAIN:
+      spdlog::error("Unregistering replica must be performed on main.");
+      slk::Save(coordination::UnregisterReplicaRes{false}, res_builder);
+      break;
+    case CAN_NOT_UNREGISTER:
+      spdlog::error("Could not unregister replica.");
+      slk::Save(coordination::UnregisterReplicaRes{false}, res_builder);
+      break;
+    case COULD_NOT_BE_PERSISTED:
+      spdlog::error("Could not persist replica unregistration.");
+      slk::Save(coordination::UnregisterReplicaRes{false}, res_builder);
+      break;
+  }
+}
+
+void CoordinatorHandlers::EnableWritingOnMainHandler(replication::ReplicationHandler &replication_handler,
+                                                     slk::Reader * /*req_reader*/, slk::Builder *res_builder) {
+  if (!replication_handler.IsMain()) {
+    spdlog::error("Enable writing on main must be performed on main!");
+    slk::Save(coordination::EnableWritingOnMainRes{false}, res_builder);
+    return;
+  }
+
+  if (!replication_handler.GetReplState().EnableWritingOnMain()) {
+    spdlog::error("Enabling writing on main failed!");
+    slk::Save(coordination::EnableWritingOnMainRes{false}, res_builder);
+    return;
+  }
+
+  slk::Save(coordination::EnableWritingOnMainRes{true}, res_builder);
+}
+
+}  // namespace memgraph::dbms
+#endif

src/coordination/coordinator_instance.cpp

@@ -0,0 +1,348 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#ifdef MG_ENTERPRISE
+
+#include "coordination/coordinator_instance.hpp"
+
+#include "coordination/coordinator_exceptions.hpp"
+#include "nuraft/coordinator_state_machine.hpp"
+#include "nuraft/coordinator_state_manager.hpp"
+#include "utils/counter.hpp"
+#include "utils/functional.hpp"
+
+#include <range/v3/view.hpp>
+#include <shared_mutex>
+
+namespace memgraph::coordination {
+
+using nuraft::ptr;
+using nuraft::srv_config;
+
+CoordinatorInstance::CoordinatorInstance()
+    : raft_state_(RaftState::MakeRaftState(
+          [this] { std::ranges::for_each(repl_instances_, &ReplicationInstance::StartFrequentCheck); },
+          [this] { std::ranges::for_each(repl_instances_, &ReplicationInstance::StopFrequentCheck); })) {
+  auto find_repl_instance = [](CoordinatorInstance *self,
+                               std::string_view repl_instance_name) -> ReplicationInstance & {
+    auto repl_instance =
+        std::ranges::find_if(self->repl_instances_, [repl_instance_name](ReplicationInstance const &instance) {
+          return instance.InstanceName() == repl_instance_name;
+        });
+
+    MG_ASSERT(repl_instance != self->repl_instances_.end(), "Instance {} not found during callback!",
+              repl_instance_name);
+    return *repl_instance;
+  };
+
+  replica_succ_cb_ = [find_repl_instance](CoordinatorInstance *self, std::string_view repl_instance_name) -> void {
+    auto lock = std::lock_guard{self->coord_instance_lock_};
+    spdlog::trace("Instance {} performing replica successful callback", repl_instance_name);
+    auto &repl_instance = find_repl_instance(self, repl_instance_name);
+
+    // We need to get replicas UUID from time to time to ensure replica is listening to correct main
+    // and that it didn't go down for less time than we could notice
+    // We need to get id of main replica is listening to
+    // and swap if necessary
+    if (!repl_instance.EnsureReplicaHasCorrectMainUUID(self->GetMainUUID())) {
+      spdlog::error("Failed to swap uuid for replica instance {} which is alive", repl_instance.InstanceName());
+      return;
+    }
+
+    repl_instance.OnSuccessPing();
+  };
+
+  replica_fail_cb_ = [find_repl_instance](CoordinatorInstance *self, std::string_view repl_instance_name) -> void {
+    auto lock = std::lock_guard{self->coord_instance_lock_};
+    spdlog::trace("Instance {} performing replica failure callback", repl_instance_name);
+    auto &repl_instance = find_repl_instance(self, repl_instance_name);
+    repl_instance.OnFailPing();
+  };
+
+  main_succ_cb_ = [find_repl_instance](CoordinatorInstance *self, std::string_view repl_instance_name) -> void {
+    auto lock = std::lock_guard{self->coord_instance_lock_};
+    spdlog::trace("Instance {} performing main successful callback", repl_instance_name);
+
+    auto &repl_instance = find_repl_instance(self, repl_instance_name);
+
+    if (repl_instance.IsAlive()) {
+      repl_instance.OnSuccessPing();
+      return;
+    }
+
+    const auto &repl_instance_uuid = repl_instance.GetMainUUID();
+    MG_ASSERT(repl_instance_uuid.has_value(), "Instance must have uuid set.");
+
+    auto const curr_main_uuid = self->GetMainUUID();
+    if (curr_main_uuid == repl_instance_uuid.value()) {
+      if (!repl_instance.EnableWritingOnMain()) {
+        spdlog::error("Failed to enable writing on main instance {}", repl_instance_name);
+        return;
+      }
+
+      repl_instance.OnSuccessPing();
+      return;
+    }
+
+    // TODO(antoniof) make demoteToReplica idempotent since main can be demoted to replica but
+    // swapUUID can fail
+    if (repl_instance.DemoteToReplica(self->replica_succ_cb_, self->replica_fail_cb_)) {
+      repl_instance.OnSuccessPing();
+      spdlog::info("Instance {} demoted to replica", repl_instance_name);
+    } else {
+      spdlog::error("Instance {} failed to become replica", repl_instance_name);
+      return;
+    }
+
+    if (!repl_instance.SendSwapAndUpdateUUID(curr_main_uuid)) {
+      spdlog::error(fmt::format("Failed to swap uuid for demoted main instance {}", repl_instance.InstanceName()));
+      return;
+    }
+  };
+
+  main_fail_cb_ = [find_repl_instance](CoordinatorInstance *self, std::string_view repl_instance_name) -> void {
+    auto lock = std::lock_guard{self->coord_instance_lock_};
+    spdlog::trace("Instance {} performing main failure callback", repl_instance_name);
+    auto &repl_instance = find_repl_instance(self, repl_instance_name);
+    repl_instance.OnFailPing();
+    const auto &repl_instance_uuid = repl_instance.GetMainUUID();
+    MG_ASSERT(repl_instance_uuid.has_value(), "Instance must have uuid set");
+
+    if (!repl_instance.IsAlive() && self->GetMainUUID() == repl_instance_uuid.value()) {
+      spdlog::info("Cluster without main instance, trying automatic failover");
+      self->TryFailover();  // TODO: (andi) Initiate failover
+    }
+  };
+}
+
+auto CoordinatorInstance::ShowInstances() const -> std::vector<InstanceStatus> {
+  auto const coord_instances = raft_state_.GetAllCoordinators();
+
+  auto const stringify_repl_role = [](ReplicationInstance const &instance) -> std::string {
+    if (!instance.IsAlive()) return "unknown";
+    if (instance.IsMain()) return "main";
+    return "replica";
+  };
+
+  auto const repl_instance_to_status = [&stringify_repl_role](ReplicationInstance const &instance) -> InstanceStatus {
+    return {.instance_name = instance.InstanceName(),
+            .coord_socket_address = instance.SocketAddress(),
+            .cluster_role = stringify_repl_role(instance),
+            .is_alive = instance.IsAlive()};
+  };
+
+  auto const coord_instance_to_status = [](ptr<srv_config> const &instance) -> InstanceStatus {
+    return {.instance_name = "coordinator_" + std::to_string(instance->get_id()),
+            .raft_socket_address = instance->get_endpoint(),
+            .cluster_role = "coordinator",
+            .is_alive = true};  // TODO: (andi) Get this info from RAFT and test it or when we will move
+                                // CoordinatorState to every instance, we can be smarter about this using our RPC.
+  };
+
+  auto instances_status = utils::fmap(coord_instance_to_status, coord_instances);
+  {
+    auto lock = std::shared_lock{coord_instance_lock_};
+    std::ranges::transform(repl_instances_, std::back_inserter(instances_status), repl_instance_to_status);
+  }
+
+  return instances_status;
+}
+
+auto CoordinatorInstance::TryFailover() -> void {
+  auto alive_replicas = repl_instances_ | ranges::views::filter(&ReplicationInstance::IsReplica) |
+                        ranges::views::filter(&ReplicationInstance::IsAlive);
+
+  if (ranges::empty(alive_replicas)) {
+    spdlog::warn("Failover failed since all replicas are down!");
+    return;
+  }
+
+  // TODO: Smarter choice
+  auto new_main = ranges::begin(alive_replicas);
+
+  new_main->PauseFrequentCheck();
+  utils::OnScopeExit scope_exit{[&new_main] { new_main->ResumeFrequentCheck(); }};
+
+  auto const is_not_new_main = [&new_main](ReplicationInstance &instance) {
+    return instance.InstanceName() != new_main->InstanceName();
+  };
+
+  auto const new_main_uuid = utils::UUID{};
+  // If for some replicas swap fails, for others on successful ping we will revert back on next change
+  // or we will do failover first again and then it will be consistent again
+  for (auto &other_replica_instance : alive_replicas | ranges::views::filter(is_not_new_main)) {
+    if (!other_replica_instance.SendSwapAndUpdateUUID(new_main_uuid)) {
+      spdlog::error(fmt::format("Failed to swap uuid for instance {} which is alive, aborting failover",
+                                other_replica_instance.InstanceName()));
+      return;
+    }
+  }
+
+  // TODO: (andi) fmap compliant
+  ReplicationClientsInfo repl_clients_info;
+  repl_clients_info.reserve(repl_instances_.size() - 1);
+  std::ranges::transform(repl_instances_ | ranges::views::filter(is_not_new_main),
+                         std::back_inserter(repl_clients_info), &ReplicationInstance::ReplicationClientInfo);
+
+  if (!new_main->PromoteToMain(new_main_uuid, std::move(repl_clients_info), main_succ_cb_, main_fail_cb_)) {
+    spdlog::warn("Failover failed since promoting replica to main failed!");
+    return;
+  }
+  // TODO: (andi) This should be replicated across all coordinator instances with Raft log
+  SetMainUUID(new_main_uuid);
+  spdlog::info("Failover successful! Instance {} promoted to main.", new_main->InstanceName());
+}
+
+// TODO: (andi) Make sure you cannot put coordinator instance to the main
+auto CoordinatorInstance::SetReplicationInstanceToMain(std::string instance_name)
+    -> SetInstanceToMainCoordinatorStatus {
+  auto lock = std::lock_guard{coord_instance_lock_};
+
+  if (std::ranges::any_of(repl_instances_, &ReplicationInstance::IsMain)) {
+    return SetInstanceToMainCoordinatorStatus::MAIN_ALREADY_EXISTS;
+  }
+
+  auto const is_new_main = [&instance_name](ReplicationInstance const &instance) {
+    return instance.InstanceName() == instance_name;
+  };
+  auto new_main = std::ranges::find_if(repl_instances_, is_new_main);
+
+  if (new_main == repl_instances_.end()) {
+    spdlog::error("Instance {} not registered. Please register it using REGISTER INSTANCE {}", instance_name,
+                  instance_name);
+    return SetInstanceToMainCoordinatorStatus::NO_INSTANCE_WITH_NAME;
+  }
+
+  new_main->PauseFrequentCheck();
+  utils::OnScopeExit scope_exit{[&new_main] { new_main->ResumeFrequentCheck(); }};
+
+  auto const is_not_new_main = [&instance_name](ReplicationInstance const &instance) {
+    return instance.InstanceName() != instance_name;
+  };
+
+  auto const new_main_uuid = utils::UUID{};
+
+  for (auto &other_instance : repl_instances_ | ranges::views::filter(is_not_new_main)) {
+    if (!other_instance.SendSwapAndUpdateUUID(new_main_uuid)) {
+      spdlog::error(
+          fmt::format("Failed to swap uuid for instance {}, aborting failover", other_instance.InstanceName()));
+      return SetInstanceToMainCoordinatorStatus::SWAP_UUID_FAILED;
+    }
+  }
+
+  ReplicationClientsInfo repl_clients_info;
+  repl_clients_info.reserve(repl_instances_.size() - 1);
+  std::ranges::transform(repl_instances_ | ranges::views::filter(is_not_new_main),
+                         std::back_inserter(repl_clients_info), &ReplicationInstance::ReplicationClientInfo);
+
+  if (!new_main->PromoteToMain(new_main_uuid, std::move(repl_clients_info), main_succ_cb_, main_fail_cb_)) {
+    return SetInstanceToMainCoordinatorStatus::COULD_NOT_PROMOTE_TO_MAIN;
+  }
+
+  // TODO: (andi) This should be replicated across all coordinator instances with Raft log
+  SetMainUUID(new_main_uuid);
+  spdlog::info("Instance {} promoted to main", instance_name);
+  return SetInstanceToMainCoordinatorStatus::SUCCESS;
+}
+
+auto CoordinatorInstance::RegisterReplicationInstance(CoordinatorClientConfig config)
+    -> RegisterInstanceCoordinatorStatus {
+  auto lock = std::lock_guard{coord_instance_lock_};
+
+  auto instance_name = config.instance_name;
+
+  auto const name_matches = [&instance_name](ReplicationInstance const &instance) {
+    return instance.InstanceName() == instance_name;
+  };
+
+  if (std::ranges::any_of(repl_instances_, name_matches)) {
+    return RegisterInstanceCoordinatorStatus::NAME_EXISTS;
+  }
+
+  auto const socket_address_matches = [&config](ReplicationInstance const &instance) {
+    return instance.SocketAddress() == config.SocketAddress();
+  };
+
+  if (std::ranges::any_of(repl_instances_, socket_address_matches)) {
+    return RegisterInstanceCoordinatorStatus::ENDPOINT_EXISTS;
+  }
+
+  if (!raft_state_.RequestLeadership()) {
+    return RegisterInstanceCoordinatorStatus::NOT_LEADER;
+  }
+
+  auto const res = raft_state_.AppendRegisterReplicationInstance(instance_name);
+  if (!res->get_accepted()) {
+    spdlog::error(
+        "Failed to accept request for registering instance {}. Most likely the reason is that the instance is not "
+        "the "
+        "leader.",
+        config.instance_name);
+    return RegisterInstanceCoordinatorStatus::RAFT_COULD_NOT_ACCEPT;
+  }
+
+  spdlog::info("Request for registering instance {} accepted", instance_name);
+  try {
+    repl_instances_.emplace_back(this, std::move(config), replica_succ_cb_, replica_fail_cb_);
+  } catch (CoordinatorRegisterInstanceException const &) {
+    return RegisterInstanceCoordinatorStatus::RPC_FAILED;
+  }
+
+  if (res->get_result_code() != nuraft::cmd_result_code::OK) {
+    spdlog::error("Failed to register instance {} with error code {}", instance_name, res->get_result_code());
+    return RegisterInstanceCoordinatorStatus::RAFT_COULD_NOT_APPEND;
+  }
+
+  spdlog::info("Instance {} registered", instance_name);
+  return RegisterInstanceCoordinatorStatus::SUCCESS;
+}
+
+auto CoordinatorInstance::UnregisterReplicationInstance(std::string instance_name)
+    -> UnregisterInstanceCoordinatorStatus {
+  auto lock = std::lock_guard{coord_instance_lock_};
+
+  auto const name_matches = [&instance_name](ReplicationInstance const &instance) {
+    return instance.InstanceName() == instance_name;
+  };
+
+  auto inst_to_remove = std::ranges::find_if(repl_instances_, name_matches);
+  if (inst_to_remove == repl_instances_.end()) {
+    return UnregisterInstanceCoordinatorStatus::NO_INSTANCE_WITH_NAME;
+  }
+
+  if (inst_to_remove->IsMain() && inst_to_remove->IsAlive()) {
+    return UnregisterInstanceCoordinatorStatus::IS_MAIN;
+  }
+
+  inst_to_remove->StopFrequentCheck();
+  auto curr_main = std::ranges::find_if(repl_instances_, &ReplicationInstance::IsMain);
+  MG_ASSERT(curr_main != repl_instances_.end(), "There must be a main instance when unregistering a replica");
+  if (!curr_main->SendUnregisterReplicaRpc(instance_name)) {
+    inst_to_remove->StartFrequentCheck();
+    return UnregisterInstanceCoordinatorStatus::RPC_FAILED;
+  }
+  std::erase_if(repl_instances_, name_matches);
+
+  return UnregisterInstanceCoordinatorStatus::SUCCESS;
+}
+
+auto CoordinatorInstance::AddCoordinatorInstance(uint32_t raft_server_id, uint32_t raft_port, std::string raft_address)
+    -> void {
+  raft_state_.AddCoordinatorInstance(raft_server_id, raft_port, std::move(raft_address));
+}
+
+auto CoordinatorInstance::GetMainUUID() const -> utils::UUID { return main_uuid_; }
+
+// TODO: (andi) Add to the RAFT log.
+auto CoordinatorInstance::SetMainUUID(utils::UUID new_uuid) -> void { main_uuid_ = new_uuid; }
+
+}  // namespace memgraph::coordination
+#endif

src/coordination/coordinator_log_store.cpp

@@ -0,0 +1,201 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#ifdef MG_ENTERPRISE
+
+#include "nuraft/coordinator_log_store.hpp"
+
+#include "coordination/coordinator_exceptions.hpp"
+#include "utils/logging.hpp"
+
+namespace memgraph::coordination {
+
+using nuraft::cs_new;
+
+namespace {
+
+ptr<log_entry> MakeClone(const ptr<log_entry> &entry) {
+  return cs_new<log_entry>(entry->get_term(), buffer::clone(entry->get_buf()), entry->get_val_type(),
+                           entry->get_timestamp());
+}
+
+}  // namespace
+
+CoordinatorLogStore::CoordinatorLogStore() : start_idx_(1) {
+  ptr<buffer> buf = buffer::alloc(sizeof(uint64_t));
+  logs_[0] = cs_new<log_entry>(0, buf);
+}
+
+CoordinatorLogStore::~CoordinatorLogStore() {}
+
+auto CoordinatorLogStore::FindOrDefault_(uint64_t index) const -> ptr<log_entry> {
+  auto entry = logs_.find(index);
+  if (entry == logs_.end()) {
+    entry = logs_.find(0);
+  }
+  return entry->second;
+}
+
+uint64_t CoordinatorLogStore::next_slot() const {
+  auto lock = std::lock_guard{logs_lock_};
+  return start_idx_ + logs_.size() - 1;
+}
+
+uint64_t CoordinatorLogStore::start_index() const { return start_idx_; }
+
+ptr<log_entry> CoordinatorLogStore::last_entry() const {
+  auto lock = std::lock_guard{logs_lock_};
+
+  uint64_t const last_idx = start_idx_ + logs_.size() - 1;
+  auto const last_src = FindOrDefault_(last_idx - 1);
+
+  return MakeClone(last_src);
+}
+
+uint64_t CoordinatorLogStore::append(ptr<log_entry> &entry) {
+  ptr<log_entry> clone = MakeClone(entry);
+  uint64_t next_slot{0};
+  {
+    auto lock = std::lock_guard{logs_lock_};
+    next_slot = start_idx_ + logs_.size() - 1;
+    logs_[next_slot] = clone;
+  }
+  return next_slot;
+}
+
+void CoordinatorLogStore::write_at(uint64_t index, ptr<log_entry> &entry) {
+  ptr<log_entry> clone = MakeClone(entry);
+
+  // Discard all logs equal to or greater than `index.
+  {
+    auto lock = std::lock_guard{logs_lock_};
+    auto itr = logs_.lower_bound(index);
+    while (itr != logs_.end()) {
+      itr = logs_.erase(itr);
+    }
+    logs_[index] = clone;
+  }
+}
+
+ptr<std::vector<ptr<log_entry>>> CoordinatorLogStore::log_entries(uint64_t start, uint64_t end) {
+  auto ret = cs_new<std::vector<ptr<log_entry>>>();
+  ret->resize(end - start);
+
+  for (uint64_t i = start, curr_index = 0; i < end; ++i, ++curr_index) {
+    ptr<log_entry> src = nullptr;
+    {
+      auto lock = std::lock_guard{logs_lock_};
+      if (auto const entry = logs_.find(i); entry != logs_.end()) {
+        src = entry->second;
+      } else {
+        throw RaftCouldNotFindEntryException("Could not find entry at index {}", i);
+      }
+    }
+    (*ret)[curr_index] = MakeClone(src);
+  }
+  return ret;
+}
+
+ptr<log_entry> CoordinatorLogStore::entry_at(uint64_t index) {
+  ptr<log_entry> src = nullptr;
+  {
+    auto lock = std::lock_guard{logs_lock_};
+    src = FindOrDefault_(index);
+  }
+  return MakeClone(src);
+}
+
+uint64_t CoordinatorLogStore::term_at(uint64_t index) {
+  uint64_t term = 0;
+  {
+    auto lock = std::lock_guard{logs_lock_};
+    term = FindOrDefault_(index)->get_term();
+  }
+  return term;
+}
+
+ptr<buffer> CoordinatorLogStore::pack(uint64_t index, int32 cnt) {
+  std::vector<ptr<buffer>> logs;
+
+  size_t size_total = 0;
+  uint64_t const end_index = index + cnt;
+  for (uint64_t i = index; i < end_index; ++i) {
+    ptr<log_entry> le = nullptr;
+    {
+      auto lock = std::lock_guard{logs_lock_};
+      le = logs_[i];
+    }
+    MG_ASSERT(le.get(), "Could not find log entry at index {}", i);
+    auto buf = le->serialize();
+    size_total += buf->size();
+    logs.push_back(buf);
+  }
+
+  auto buf_out = buffer::alloc(sizeof(int32) + cnt * sizeof(int32) + size_total);
+  buf_out->pos(0);
+  buf_out->put((int32)cnt);
+
+  for (auto &entry : logs) {
+    buf_out->put(static_cast<int32>(entry->size()));
+    buf_out->put(*entry);
+  }
+  return buf_out;
+}
+
+void CoordinatorLogStore::apply_pack(uint64_t index, buffer &pack) {
+  pack.pos(0);
+  int32 const num_logs = pack.get_int();
+
+  for (int32 i = 0; i < num_logs; ++i) {
+    uint64_t cur_idx = index + i;
+    int32 buf_size = pack.get_int();
+
+    ptr<buffer> buf_local = buffer::alloc(buf_size);
+    pack.get(buf_local);
+
+    ptr<log_entry> le = log_entry::deserialize(*buf_local);
+    {
+      auto lock = std::lock_guard{logs_lock_};
+      logs_[cur_idx] = le;
+    }
+  }
+
+  {
+    auto lock = std::lock_guard{logs_lock_};
+    auto const entry = logs_.upper_bound(0);
+    if (entry != logs_.end()) {
+      start_idx_ = entry->first;
+    } else {
+      start_idx_ = 1;
+    }
+  }
+}
+
+// NOTE: Remove all logs up to given 'last_log_index' (inclusive).
+bool CoordinatorLogStore::compact(uint64_t last_log_index) {
+  auto lock = std::lock_guard{logs_lock_};
+  for (uint64_t ii = start_idx_; ii <= last_log_index; ++ii) {
+    auto const entry = logs_.find(ii);
+    if (entry != logs_.end()) {
+      logs_.erase(entry);
+    }
+  }
+
+  if (start_idx_ <= last_log_index) {
+    start_idx_ = last_log_index + 1;
+  }
+  return true;
+}
+
+bool CoordinatorLogStore::flush() { return true; }
+
+}  // namespace memgraph::coordination
+#endif

src/coordination/coordinator_rpc.cpp

@@ -36,6 +36,67 @@ void PromoteReplicaToMainRes::Load(PromoteReplicaToMainRes *self, memgraph::slk:
   memgraph::slk::Load(self, reader);
 }
 
+void DemoteMainToReplicaReq::Save(const DemoteMainToReplicaReq &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self, builder);
+}
+
+void DemoteMainToReplicaReq::Load(DemoteMainToReplicaReq *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(self, reader);
+}
+
+void DemoteMainToReplicaRes::Save(const DemoteMainToReplicaRes &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self, builder);
+}
+
+void DemoteMainToReplicaRes::Load(DemoteMainToReplicaRes *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(self, reader);
+}
+
+void UnregisterReplicaReq::Save(UnregisterReplicaReq const &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self, builder);
+}
+
+void UnregisterReplicaReq::Load(UnregisterReplicaReq *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(self, reader);
+}
+
+void UnregisterReplicaRes::Save(UnregisterReplicaRes const &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self, builder);
+}
+
+void UnregisterReplicaRes::Load(UnregisterReplicaRes *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(self, reader);
+}
+
+void EnableWritingOnMainRes::Save(EnableWritingOnMainRes const &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self, builder);
+}
+
+void EnableWritingOnMainRes::Load(EnableWritingOnMainRes *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(self, reader);
+}
+
+void EnableWritingOnMainReq::Save(EnableWritingOnMainReq const &self, memgraph::slk::Builder *builder) {}
+
+void EnableWritingOnMainReq::Load(EnableWritingOnMainReq *self, memgraph::slk::Reader *reader) {}
+
+// GetInstanceUUID
+void GetInstanceUUIDReq::Save(const GetInstanceUUIDReq &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self, builder);
+}
+
+void GetInstanceUUIDReq::Load(GetInstanceUUIDReq *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(self, reader);
+}
+
+void GetInstanceUUIDRes::Save(const GetInstanceUUIDRes &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self, builder);
+}
+
+void GetInstanceUUIDRes::Load(GetInstanceUUIDRes *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(self, reader);
+}
+
 }  // namespace coordination
 
 constexpr utils::TypeInfo coordination::PromoteReplicaToMainReq::kType{utils::TypeId::COORD_FAILOVER_REQ,
@@ -44,8 +105,35 @@ constexpr utils::TypeInfo coordination::PromoteReplicaToMainReq::kType{utils::Ty
 constexpr utils::TypeInfo coordination::PromoteReplicaToMainRes::kType{utils::TypeId::COORD_FAILOVER_RES,
                                                                        "CoordPromoteReplicaToMainRes", nullptr};
 
+constexpr utils::TypeInfo coordination::DemoteMainToReplicaReq::kType{utils::TypeId::COORD_SET_REPL_MAIN_REQ,
+                                                                      "CoordDemoteToReplicaReq", nullptr};
+
+constexpr utils::TypeInfo coordination::DemoteMainToReplicaRes::kType{utils::TypeId::COORD_SET_REPL_MAIN_RES,
+
+                                                                      "CoordDemoteToReplicaRes", nullptr};
+
+constexpr utils::TypeInfo coordination::UnregisterReplicaReq::kType{utils::TypeId::COORD_UNREGISTER_REPLICA_REQ,
+                                                                    "UnregisterReplicaReq", nullptr};
+
+constexpr utils::TypeInfo coordination::UnregisterReplicaRes::kType{utils::TypeId::COORD_UNREGISTER_REPLICA_RES,
+                                                                    "UnregisterReplicaRes", nullptr};
+
+constexpr utils::TypeInfo coordination::EnableWritingOnMainReq::kType{utils::TypeId::COORD_ENABLE_WRITING_ON_MAIN_REQ,
+                                                                      "CoordEnableWritingOnMainReq", nullptr};
+
+constexpr utils::TypeInfo coordination::EnableWritingOnMainRes::kType{utils::TypeId::COORD_ENABLE_WRITING_ON_MAIN_RES,
+                                                                      "CoordEnableWritingOnMainRes", nullptr};
+
+constexpr utils::TypeInfo coordination::GetInstanceUUIDReq::kType{utils::TypeId::COORD_GET_UUID_REQ, "CoordGetUUIDReq",
+                                                                  nullptr};
+
+constexpr utils::TypeInfo coordination::GetInstanceUUIDRes::kType{utils::TypeId::COORD_GET_UUID_RES, "CoordGetUUIDRes",
+                                                                  nullptr};
+
 namespace slk {
 
+// PromoteReplicaToMainRpc
+
 void Save(const memgraph::coordination::PromoteReplicaToMainRes &self, memgraph::slk::Builder *builder) {
   memgraph::slk::Save(self.success, builder);
 }
@@ -55,13 +143,76 @@ void Load(memgraph::coordination::PromoteReplicaToMainRes *self, memgraph::slk::
 }
 
 void Save(const memgraph::coordination::PromoteReplicaToMainReq &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self.main_uuid_, builder);
   memgraph::slk::Save(self.replication_clients_info, builder);
 }
 
 void Load(memgraph::coordination::PromoteReplicaToMainReq *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(&self->main_uuid_, reader);
   memgraph::slk::Load(&self->replication_clients_info, reader);
 }
 
+// DemoteMainToReplicaRpc
+void Save(const memgraph::coordination::DemoteMainToReplicaReq &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self.replication_client_info, builder);
+}
+
+void Load(memgraph::coordination::DemoteMainToReplicaReq *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(&self->replication_client_info, reader);
+}
+
+void Save(const memgraph::coordination::DemoteMainToReplicaRes &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self.success, builder);
+}
+
+void Load(memgraph::coordination::DemoteMainToReplicaRes *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(&self->success, reader);
+}
+
+// UnregisterReplicaRpc
+
+void Save(memgraph::coordination::UnregisterReplicaReq const &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self.instance_name, builder);
+}
+
+void Load(memgraph::coordination::UnregisterReplicaReq *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(&self->instance_name, reader);
+}
+
+void Save(memgraph::coordination::UnregisterReplicaRes const &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self.success, builder);
+}
+
+void Load(memgraph::coordination::UnregisterReplicaRes *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(&self->success, reader);
+}
+
+void Save(memgraph::coordination::EnableWritingOnMainRes const &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self.success, builder);
+}
+
+void Load(memgraph::coordination::EnableWritingOnMainRes *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(&self->success, reader);
+}
+
+// GetInstanceUUIDRpc
+
+void Save(const memgraph::coordination::GetInstanceUUIDReq & /*self*/, memgraph::slk::Builder * /*builder*/) {
+  /* nothing to serialize*/
+}
+
+void Load(memgraph::coordination::GetInstanceUUIDReq * /*self*/, memgraph::slk::Reader * /*reader*/) {
+  /* nothing to serialize*/
+}
+
+void Save(const memgraph::coordination::GetInstanceUUIDRes &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self.uuid, builder);
+}
+
+void Load(memgraph::coordination::GetInstanceUUIDRes *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(&self->uuid, reader);
+}
+
 }  // namespace slk
 
 }  // namespace memgraph

src/coordination/coordinator_server.cpp

@@ -12,7 +12,7 @@
 #ifdef MG_ENTERPRISE
 
 #include "coordination/coordinator_server.hpp"
-#include "replication_coordination_glue/messages.hpp"
+#include "replication_coordination_glue/handler.hpp"
 
 namespace memgraph::coordination {
 

src/coordination/coordinator_state.cpp

@@ -9,207 +9,85 @@
 // by the Apache License, Version 2.0, included in the file
 // licenses/APL.txt.
 
-#include "coordination/coordinator_state.hpp"
-#include <span>
-#include "coordination/coordinator_client.hpp"
-
 #ifdef MG_ENTERPRISE
 
+#include "coordination/coordinator_state.hpp"
+
 #include "coordination/coordinator_config.hpp"
-#include "coordination/coordinator_entity_info.hpp"
+#include "coordination/register_main_replica_coordinator_status.hpp"
 #include "flags/replication.hpp"
 #include "spdlog/spdlog.h"
 #include "utils/logging.hpp"
 #include "utils/variant_helpers.hpp"
 
-#include <atomic>
-#include <exception>
-#include <optional>
+#include <algorithm>
 
 namespace memgraph::coordination {
 
-namespace {
-
-bool CheckName(const std::list<CoordinatorClient> &replicas, const CoordinatorClientConfig &config) {
-  auto name_matches = [&instance_name = config.instance_name](auto const &replica) {
-    return replica.InstanceName() == instance_name;
-  };
-  return std::any_of(replicas.begin(), replicas.end(), name_matches);
-};
-
-}  // namespace
-
 CoordinatorState::CoordinatorState() {
-  MG_ASSERT(!(FLAGS_coordinator && FLAGS_coordinator_server_port),
+  MG_ASSERT(!(FLAGS_raft_server_id && FLAGS_coordinator_server_port),
             "Instance cannot be a coordinator and have registered coordinator server.");
 
+  spdlog::info("Executing coordinator constructor");
   if (FLAGS_coordinator_server_port) {
+    spdlog::info("Coordinator server port set");
     auto const config = CoordinatorServerConfig{
         .ip_address = kDefaultReplicationServerIp,
         .port = static_cast<uint16_t>(FLAGS_coordinator_server_port),
     };
+    spdlog::info("Executing coordinator constructor main replica");
 
     data_ = CoordinatorMainReplicaData{.coordinator_server_ = std::make_unique<CoordinatorServer>(config)};
   }
 }
 
-auto CoordinatorState::RegisterReplica(const CoordinatorClientConfig &config)
-    -> utils::BasicResult<RegisterMainReplicaCoordinatorStatus, CoordinatorClient *> {
-  const auto name_endpoint_status =
-      std::visit(memgraph::utils::Overloaded{[](const CoordinatorMainReplicaData & /*coordinator_main_replica_data*/) {
-                                               return RegisterMainReplicaCoordinatorStatus::NOT_COORDINATOR;
-                                             },
-                                             [&config](const CoordinatorData &coordinator_data) {
-                                               if (memgraph::coordination::CheckName(
-                                                       coordinator_data.registered_replicas_, config)) {
-                                                 return RegisterMainReplicaCoordinatorStatus::NAME_EXISTS;
-                                               }
-                                               return RegisterMainReplicaCoordinatorStatus::SUCCESS;
-                                             }},
-                 data_);
+auto CoordinatorState::RegisterReplicationInstance(CoordinatorClientConfig config)
+    -> RegisterInstanceCoordinatorStatus {
+  MG_ASSERT(std::holds_alternative<CoordinatorInstance>(data_),
+            "Coordinator cannot register replica since variant holds wrong alternative");
 
-  if (name_endpoint_status != RegisterMainReplicaCoordinatorStatus::SUCCESS) {
-    return name_endpoint_status;
-  }
-
-  // Maybe no need to return client if you can start replica client here
-  return &std::get<CoordinatorData>(data_).registered_replicas_.emplace_back(config);
-}
-
-auto CoordinatorState::RegisterMain(const CoordinatorClientConfig &config)
-    -> utils::BasicResult<RegisterMainReplicaCoordinatorStatus, CoordinatorClient *> {
-  const auto endpoint_status = std::visit(
-      memgraph::utils::Overloaded{
-          [](const CoordinatorMainReplicaData & /*coordinator_main_replica_data*/) {
-            return RegisterMainReplicaCoordinatorStatus::NOT_COORDINATOR;
-          },
-          [](const CoordinatorData & /*coordinator_data*/) { return RegisterMainReplicaCoordinatorStatus::SUCCESS; }},
+  return std::visit(
+      memgraph::utils::Overloaded{[](const CoordinatorMainReplicaData & /*coordinator_main_replica_data*/) {
+                                    return RegisterInstanceCoordinatorStatus::NOT_COORDINATOR;
+                                  },
+                                  [config](CoordinatorInstance &coordinator_instance) {
+                                    return coordinator_instance.RegisterReplicationInstance(config);
+                                  }},
       data_);
-
-  if (endpoint_status != RegisterMainReplicaCoordinatorStatus::SUCCESS) {
-    return endpoint_status;
-  }
-
-  auto &registered_main = std::get<CoordinatorData>(data_).registered_main_;
-  registered_main = std::make_unique<CoordinatorClient>(config);
-  return registered_main.get();
 }
 
-auto CoordinatorState::ShowReplicas() const -> std::vector<CoordinatorEntityInfo> {
-  MG_ASSERT(std::holds_alternative<CoordinatorData>(data_),
-            "Can't call show replicas on data_, as variant holds wrong alternative");
-  std::vector<CoordinatorEntityInfo> result;
-  const auto &registered_replicas = std::get<CoordinatorData>(data_).registered_replicas_;
-  result.reserve(registered_replicas.size());
-  std::ranges::transform(registered_replicas, std::back_inserter(result), [](const auto &replica) {
-    return CoordinatorEntityInfo{replica.InstanceName(), replica.Endpoint()};
-  });
-  return result;
+auto CoordinatorState::UnregisterReplicationInstance(std::string instance_name) -> UnregisterInstanceCoordinatorStatus {
+  MG_ASSERT(std::holds_alternative<CoordinatorInstance>(data_),
+            "Coordinator cannot unregister instance since variant holds wrong alternative");
+
+  return std::visit(
+      memgraph::utils::Overloaded{[](const CoordinatorMainReplicaData & /*coordinator_main_replica_data*/) {
+                                    return UnregisterInstanceCoordinatorStatus::NOT_COORDINATOR;
+                                  },
+                                  [&instance_name](CoordinatorInstance &coordinator_instance) {
+                                    return coordinator_instance.UnregisterReplicationInstance(instance_name);
+                                  }},
+      data_);
 }
 
-auto CoordinatorState::ShowMain() const -> std::optional<CoordinatorEntityInfo> {
-  MG_ASSERT(std::holds_alternative<CoordinatorData>(data_),
-            "Can't call show main on data_, as variant holds wrong alternative");
-  const auto &registered_main = std::get<CoordinatorData>(data_).registered_main_;
-  if (registered_main) {
-    return CoordinatorEntityInfo{registered_main->InstanceName(), registered_main->Endpoint()};
-  }
-  return std::nullopt;
+auto CoordinatorState::SetReplicationInstanceToMain(std::string instance_name) -> SetInstanceToMainCoordinatorStatus {
+  MG_ASSERT(std::holds_alternative<CoordinatorInstance>(data_),
+            "Coordinator cannot register replica since variant holds wrong alternative");
+
+  return std::visit(
+      memgraph::utils::Overloaded{[](const CoordinatorMainReplicaData & /*coordinator_main_replica_data*/) {
+                                    return SetInstanceToMainCoordinatorStatus::NOT_COORDINATOR;
+                                  },
+                                  [&instance_name](CoordinatorInstance &coordinator_instance) {
+                                    return coordinator_instance.SetReplicationInstanceToMain(instance_name);
+                                  }},
+      data_);
 }
 
-auto CoordinatorState::PingReplicas() const -> std::unordered_map<std::string_view, bool> {
-  MG_ASSERT(std::holds_alternative<CoordinatorData>(data_),
-            "Can't call ping replicas on data_, as variant holds wrong alternative");
-  std::unordered_map<std::string_view, bool> result;
-  const auto &registered_replicas = std::get<CoordinatorData>(data_).registered_replicas_;
-  result.reserve(registered_replicas.size());
-  for (const CoordinatorClient &replica_client : registered_replicas) {
-    result.emplace(replica_client.InstanceName(), replica_client.DoHealthCheck());
-  }
-
-  return result;
-}
-
-auto CoordinatorState::PingMain() const -> std::optional<CoordinatorEntityHealthInfo> {
-  MG_ASSERT(std::holds_alternative<CoordinatorData>(data_),
-            "Can't call show main on data_, as variant holds wrong alternative");
-  const auto &registered_main = std::get<CoordinatorData>(data_).registered_main_;
-  if (registered_main) {
-    return CoordinatorEntityHealthInfo{registered_main->InstanceName(), registered_main->DoHealthCheck()};
-  }
-  return std::nullopt;
-}
-
-auto CoordinatorState::DoFailover() -> DoFailoverStatus {
-  // 1. MAIN is already down, stop sending frequent checks
-  // 2. find new replica (coordinator)
-  // 3. make copy replica's client as potential new main client (coordinator)
-  // 4. send failover RPC to new main (coordinator and new main)
-  // 5. exchange old main to new main (coordinator)
-  // 6. remove replica which was promoted to main from all replicas -> this will shut down RPC frequent check client
-  // (coordinator)
-  // 7. for new main start frequent checks (coordinator)
-
-  MG_ASSERT(std::holds_alternative<CoordinatorData>(data_), "Cannot do failover since variant holds wrong alternative");
-  using ReplicationClientInfo = CoordinatorClientConfig::ReplicationClientInfo;
-
-  // 1.
-  auto &current_main = std::get<CoordinatorData>(data_).registered_main_;
-
-  if (!current_main) {
-    return DoFailoverStatus::CLUSTER_UNINITIALIZED;
-  }
-
-  if (current_main->DoHealthCheck()) {
-    return DoFailoverStatus::MAIN_ALIVE;
-  }
-  current_main->StopFrequentCheck();
-
-  // 2.
-  // Get all replicas and find new main
-  auto &registered_replicas = std::get<CoordinatorData>(data_).registered_replicas_;
-
-  const auto chosen_replica = std::ranges::find_if(
-      registered_replicas, [](const CoordinatorClient &replica) { return replica.DoHealthCheck(); });
-  if (chosen_replica == registered_replicas.end()) {
-    return DoFailoverStatus::ALL_REPLICAS_DOWN;
-  }
-
-  std::vector<ReplicationClientInfo> repl_clients_info;
-  repl_clients_info.reserve(registered_replicas.size() - 1);
-  std::ranges::for_each(registered_replicas, [&chosen_replica, &repl_clients_info](const CoordinatorClient &replica) {
-    if (replica != *chosen_replica) {
-      repl_clients_info.emplace_back(replica.ReplicationClientInfo());
-    }
-  });
-
-  // 3.
-  // Set on coordinator data of new main
-  // allocate resources for new main, clear replication info on this replica as main
-  // set last response time
-  auto potential_new_main = std::make_unique<CoordinatorClient>(chosen_replica->Config());
-  potential_new_main->ReplicationClientInfo().reset();
-  potential_new_main->UpdateTimeCheck(chosen_replica->GetLastTimeResponse());
-
-  // 4.
-  if (!chosen_replica->SendPromoteReplicaToMainRpc(std::move(repl_clients_info))) {
-    spdlog::error("Sent RPC message, but exception was caught, aborting Failover");
-    // TODO: new status and rollback all changes that were done...
-    MG_ASSERT(false, "RPC message failed");
-  }
-
-  // 5.
-  current_main = std::move(potential_new_main);
-
-  // 6. remove old replica
-  // TODO: Stop pinging chosen_replica before failover.
-  // Check that it doesn't fail when you call StopFrequentCheck if it is already stopped
-  registered_replicas.erase(chosen_replica);
-
-  // 7.
-  current_main->StartFrequentCheck();
-
-  return DoFailoverStatus::SUCCESS;
+auto CoordinatorState::ShowInstances() const -> std::vector<InstanceStatus> {
+  MG_ASSERT(std::holds_alternative<CoordinatorInstance>(data_),
+            "Can't call show instances on data_, as variant holds wrong alternative");
+  return std::get<CoordinatorInstance>(data_).ShowInstances();
 }
 
 auto CoordinatorState::GetCoordinatorServer() const -> CoordinatorServer & {
@@ -217,5 +95,13 @@ auto CoordinatorState::GetCoordinatorServer() const -> CoordinatorServer & {
             "Cannot get coordinator server since variant holds wrong alternative");
   return *std::get<CoordinatorMainReplicaData>(data_).coordinator_server_;
 }
+
+auto CoordinatorState::AddCoordinatorInstance(uint32_t raft_server_id, uint32_t raft_port, std::string raft_address)
+    -> void {
+  MG_ASSERT(std::holds_alternative<CoordinatorInstance>(data_),
+            "Coordinator cannot register replica since variant holds wrong alternative");
+  return std::get<CoordinatorInstance>(data_).AddCoordinatorInstance(raft_server_id, raft_port, raft_address);
+}
+
 }  // namespace memgraph::coordination
 #endif

src/coordination/coordinator_state_machine.cpp

@@ -0,0 +1,111 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#ifdef MG_ENTERPRISE
+
+#include "nuraft/coordinator_state_machine.hpp"
+
+namespace memgraph::coordination {
+
+auto CoordinatorStateMachine::EncodeRegisterReplicationInstance(const std::string &name) -> ptr<buffer> {
+  std::string str_log = name + "_replica";
+  ptr<buffer> log = buffer::alloc(sizeof(uint32_t) + str_log.size());
+  buffer_serializer bs(log);
+  bs.put_str(str_log);
+  return log;
+}
+
+auto CoordinatorStateMachine::DecodeRegisterReplicationInstance(buffer &data) -> std::string {
+  buffer_serializer bs(data);
+  return bs.get_str();
+}
+
+auto CoordinatorStateMachine::pre_commit(ulong const log_idx, buffer &data) -> ptr<buffer> {
+  buffer_serializer bs(data);
+  std::string str = bs.get_str();
+
+  spdlog::info("pre_commit {} : {}", log_idx, str);
+  return nullptr;
+}
+
+auto CoordinatorStateMachine::commit(ulong const log_idx, buffer &data) -> ptr<buffer> {
+  buffer_serializer bs(data);
+  std::string str = bs.get_str();
+
+  spdlog::info("commit {} : {}", log_idx, str);
+
+  last_committed_idx_ = log_idx;
+  return nullptr;
+}
+
+auto CoordinatorStateMachine::commit_config(ulong const log_idx, ptr<cluster_config> & /*new_conf*/) -> void {
+  last_committed_idx_ = log_idx;
+}
+
+auto CoordinatorStateMachine::rollback(ulong const log_idx, buffer &data) -> void {
+  buffer_serializer bs(data);
+  std::string str = bs.get_str();
+
+  spdlog::info("rollback {} : {}", log_idx, str);
+}
+
+auto CoordinatorStateMachine::read_logical_snp_obj(snapshot & /*snapshot*/, void *& /*user_snp_ctx*/, ulong /*obj_id*/,
+                                                   ptr<buffer> &data_out, bool &is_last_obj) -> int {
+  // Put dummy data.
+  data_out = buffer::alloc(sizeof(int32));
+  buffer_serializer bs(data_out);
+  bs.put_i32(0);
+
+  is_last_obj = true;
+  return 0;
+}
+
+auto CoordinatorStateMachine::save_logical_snp_obj(snapshot &s, ulong &obj_id, buffer & /*data*/, bool /*is_first_obj*/,
+                                                   bool /*is_last_obj*/) -> void {
+  spdlog::info("save snapshot {} term {} object ID", s.get_last_log_idx(), s.get_last_log_term(), obj_id);
+  // Request next object.
+  obj_id++;
+}
+
+auto CoordinatorStateMachine::apply_snapshot(snapshot &s) -> bool {
+  spdlog::info("apply snapshot {} term {}", s.get_last_log_idx(), s.get_last_log_term());
+  {
+    auto lock = std::lock_guard{last_snapshot_lock_};
+    ptr<buffer> snp_buf = s.serialize();
+    last_snapshot_ = snapshot::deserialize(*snp_buf);
+  }
+  return true;
+}
+
+auto CoordinatorStateMachine::free_user_snp_ctx(void *&user_snp_ctx) -> void {}
+
+auto CoordinatorStateMachine::last_snapshot() -> ptr<snapshot> {
+  auto lock = std::lock_guard{last_snapshot_lock_};
+  return last_snapshot_;
+}
+
+auto CoordinatorStateMachine::last_commit_index() -> ulong { return last_committed_idx_; }
+
+auto CoordinatorStateMachine::create_snapshot(snapshot &s, async_result<bool>::handler_type &when_done) -> void {
+  spdlog::info("create snapshot {} term {}", s.get_last_log_idx(), s.get_last_log_term());
+  // Clone snapshot from `s`.
+  {
+    auto lock = std::lock_guard{last_snapshot_lock_};
+    ptr<buffer> snp_buf = s.serialize();
+    last_snapshot_ = snapshot::deserialize(*snp_buf);
+  }
+  ptr<std::exception> except(nullptr);
+  bool ret = true;
+  when_done(ret, except);
+}
+
+}  // namespace memgraph::coordination
+#endif

src/coordination/coordinator_state_manager.cpp

@@ -0,0 +1,68 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#ifdef MG_ENTERPRISE
+
+#include "nuraft/coordinator_state_manager.hpp"
+
+namespace memgraph::coordination {
+
+using nuraft::cluster_config;
+using nuraft::cs_new;
+using nuraft::srv_config;
+using nuraft::srv_state;
+using nuraft::state_mgr;
+
+CoordinatorStateManager::CoordinatorStateManager(int srv_id, std::string const &endpoint)
+    : my_id_(srv_id), my_endpoint_(endpoint), cur_log_store_(cs_new<CoordinatorLogStore>()) {
+  my_srv_config_ = cs_new<srv_config>(srv_id, endpoint);
+
+  // Initial cluster config: contains only one server (myself).
+  cluster_config_ = cs_new<cluster_config>();
+  cluster_config_->get_servers().push_back(my_srv_config_);
+}
+
+auto CoordinatorStateManager::load_config() -> ptr<cluster_config> {
+  // Just return in-memory data in this example.
+  // May require reading from disk here, if it has been written to disk.
+  return cluster_config_;
+}
+
+auto CoordinatorStateManager::save_config(cluster_config const &config) -> void {
+  // Just keep in memory in this example.
+  // Need to write to disk here, if want to make it durable.
+  ptr<buffer> buf = config.serialize();
+  cluster_config_ = cluster_config::deserialize(*buf);
+}
+
+auto CoordinatorStateManager::save_state(srv_state const &state) -> void {
+  // Just keep in memory in this example.
+  // Need to write to disk here, if want to make it durable.
+  ptr<buffer> buf = state.serialize();
+  saved_state_ = srv_state::deserialize(*buf);
+}
+
+auto CoordinatorStateManager::read_state() -> ptr<srv_state> {
+  // Just return in-memory data in this example.
+  // May require reading from disk here, if it has been written to disk.
+  return saved_state_;
+}
+
+auto CoordinatorStateManager::load_log_store() -> ptr<log_store> { return cur_log_store_; }
+
+auto CoordinatorStateManager::server_id() -> int32 { return my_id_; }
+
+auto CoordinatorStateManager::system_exit(int const exit_code) -> void {}
+
+auto CoordinatorStateManager::GetSrvConfig() const -> ptr<srv_config> { return my_srv_config_; }
+
+}  // namespace memgraph::coordination
+#endif

src/coordination/include/coordination/coordinator_client.hpp

@@ -15,54 +15,75 @@
 
 #include "coordination/coordinator_config.hpp"
 #include "rpc/client.hpp"
+#include "rpc_errors.hpp"
+#include "utils/result.hpp"
 #include "utils/scheduler.hpp"
-#include "utils/thread_pool.hpp"
-
-#include <string_view>
+#include "utils/uuid.hpp"
 
 namespace memgraph::coordination {
 
+class CoordinatorInstance;
+using HealthCheckCallback = std::function<void(CoordinatorInstance *, std::string_view)>;
+using ReplicationClientsInfo = std::vector<ReplClientInfo>;
+
 class CoordinatorClient {
  public:
-  explicit CoordinatorClient(const CoordinatorClientConfig &config);
+  explicit CoordinatorClient(CoordinatorInstance *coord_instance, CoordinatorClientConfig config,
+                             HealthCheckCallback succ_cb, HealthCheckCallback fail_cb);
 
-  ~CoordinatorClient();
+  ~CoordinatorClient() = default;
 
-  CoordinatorClient(CoordinatorClient &other) = delete;
-  CoordinatorClient &operator=(CoordinatorClient const &other) = delete;
+  CoordinatorClient(CoordinatorClient &) = delete;
+  CoordinatorClient &operator=(CoordinatorClient const &) = delete;
 
   CoordinatorClient(CoordinatorClient &&) noexcept = delete;
   CoordinatorClient &operator=(CoordinatorClient &&) noexcept = delete;
 
   void StartFrequentCheck();
   void StopFrequentCheck();
+  void PauseFrequentCheck();
+  void ResumeFrequentCheck();
 
-  auto DoHealthCheck() const -> bool;
-  auto SendPromoteReplicaToMainRpc(
-      std::vector<CoordinatorClientConfig::ReplicationClientInfo> replication_clients_info) const -> bool;
+  auto InstanceName() const -> std::string;
+  auto SocketAddress() const -> std::string;
 
-  auto InstanceName() const -> std::string_view;
-  auto Endpoint() const -> io::network::Endpoint const &;
-  auto Config() const -> CoordinatorClientConfig const &;
-  auto ReplicationClientInfo() const -> CoordinatorClientConfig::ReplicationClientInfo const &;
-  auto ReplicationClientInfo() -> std::optional<CoordinatorClientConfig::ReplicationClientInfo> &;
-  void UpdateTimeCheck(const std::chrono::system_clock::time_point &last_checked_time);
-  auto GetLastTimeResponse() -> std::chrono::system_clock::time_point;
+  [[nodiscard]] auto DemoteToReplica() const -> bool;
+
+  auto SendPromoteReplicaToMainRpc(const utils::UUID &uuid, ReplicationClientsInfo replication_clients_info) const
+      -> bool;
+
+  auto SendSwapMainUUIDRpc(const utils::UUID &uuid) const -> bool;
+
+  auto SendUnregisterReplicaRpc(std::string const &instance_name) const -> bool;
+
+  auto SendEnableWritingOnMainRpc() const -> bool;
+
+  auto SendGetInstanceUUIDRpc() const -> memgraph::utils::BasicResult<GetInstanceUUIDError, std::optional<utils::UUID>>;
+
+  auto ReplicationClientInfo() const -> ReplClientInfo;
+
+  auto SetCallbacks(HealthCheckCallback succ_cb, HealthCheckCallback fail_cb) -> void;
+
+  auto RpcClient() -> rpc::Client & { return rpc_client_; }
+
+  auto InstanceDownTimeoutSec() const -> std::chrono::seconds;
+
+  auto InstanceGetUUIDFrequencySec() const -> std::chrono::seconds;
 
   friend bool operator==(CoordinatorClient const &first, CoordinatorClient const &second) {
     return first.config_ == second.config_;
   }
 
  private:
-  utils::ThreadPool thread_pool_{1};
-  utils::Scheduler replica_checker_;
+  utils::Scheduler instance_checker_;
 
   communication::ClientContext rpc_context_;
   mutable rpc::Client rpc_client_;
-  CoordinatorClientConfig config_;
 
-  std::atomic<std::chrono::system_clock::time_point> last_response_time_{};
-  static constexpr int alive_response_time_difference_sec_{5};
+  CoordinatorClientConfig config_;
+  CoordinatorInstance *coord_instance_;
+  HealthCheckCallback succ_cb_;
+  HealthCheckCallback fail_cb_;
 };
 
 }  // namespace memgraph::coordination

src/coordination/include/coordination/coordinator_config.hpp

@@ -25,16 +25,16 @@ namespace memgraph::coordination {
 inline constexpr auto *kDefaultReplicationServerIp = "0.0.0.0";
 
 struct CoordinatorClientConfig {
-  const std::string instance_name;
-  const std::string ip_address;
-  const uint16_t port{};
+  std::string instance_name;
+  std::string ip_address;
+  uint16_t port{};
+  std::chrono::seconds instance_health_check_frequency_sec{1};
+  std::chrono::seconds instance_down_timeout_sec{5};
+  std::chrono::seconds instance_get_uuid_frequency_sec{10};
 
-  // Frequency with which coordinator pings main/replicas about it status
-  const std::chrono::seconds health_check_frequency_sec{1};
+  auto SocketAddress() const -> std::string { return ip_address + ":" + std::to_string(port); }
 
-  // Info which coordinator will send to new main when performing failover
   struct ReplicationClientInfo {
-    // Should be the same as CoordinatorClientConfig's instance_name
     std::string instance_name;
     replication_coordination_glue::ReplicationMode replication_mode{};
     std::string replication_ip_address;
@@ -43,20 +43,22 @@ struct CoordinatorClientConfig {
     friend bool operator==(ReplicationClientInfo const &, ReplicationClientInfo const &) = default;
   };
 
-  std::optional<ReplicationClientInfo> replication_client_info;
+  ReplicationClientInfo replication_client_info;
 
   struct SSL {
-    const std::string key_file;
-    const std::string cert_file;
+    std::string key_file;
+    std::string cert_file;
 
     friend bool operator==(const SSL &, const SSL &) = default;
   };
 
-  const std::optional<SSL> ssl;
+  std::optional<SSL> ssl;
 
   friend bool operator==(CoordinatorClientConfig const &, CoordinatorClientConfig const &) = default;
 };
 
+using ReplClientInfo = CoordinatorClientConfig::ReplicationClientInfo;
+
 struct CoordinatorServerConfig {
   std::string ip_address;
   uint16_t port{};

src/coordination/include/coordination/coordinator_exceptions.hpp

@@ -16,16 +16,71 @@
 #include "utils/exceptions.hpp"
 
 namespace memgraph::coordination {
-class CoordinatorFailoverException final : public utils::BasicException {
+class CoordinatorRegisterInstanceException final : public utils::BasicException {
  public:
-  explicit CoordinatorFailoverException(const std::string_view what) noexcept
-      : BasicException("Failover didn't complete successfully: " + std::string(what)) {}
+  explicit CoordinatorRegisterInstanceException(const std::string_view what) noexcept
+      : BasicException("Failed to create instance: " + std::string(what)) {}
 
   template <class... Args>
-  explicit CoordinatorFailoverException(fmt::format_string<Args...> fmt, Args &&...args) noexcept
-      : CoordinatorFailoverException(fmt::format(fmt, std::forward<Args>(args)...)) {}
+  explicit CoordinatorRegisterInstanceException(fmt::format_string<Args...> fmt, Args &&...args) noexcept
+      : CoordinatorRegisterInstanceException(fmt::format(fmt, std::forward<Args>(args)...)) {}
 
-  SPECIALIZE_GET_EXCEPTION_NAME(CoordinatorFailoverException)
+  SPECIALIZE_GET_EXCEPTION_NAME(CoordinatorRegisterInstanceException)
+};
+
+class RaftServerStartException final : public utils::BasicException {
+ public:
+  explicit RaftServerStartException(std::string_view what) noexcept : BasicException(what) {}
+
+  template <class... Args>
+  explicit RaftServerStartException(fmt::format_string<Args...> fmt, Args &&...args) noexcept
+      : RaftServerStartException(fmt::format(fmt, std::forward<Args>(args)...)) {}
+
+  SPECIALIZE_GET_EXCEPTION_NAME(RaftServerStartException)
+};
+
+class RaftAddServerException final : public utils::BasicException {
+ public:
+  explicit RaftAddServerException(std::string_view what) noexcept : BasicException(what) {}
+
+  template <class... Args>
+  explicit RaftAddServerException(fmt::format_string<Args...> fmt, Args &&...args) noexcept
+      : RaftAddServerException(fmt::format(fmt, std::forward<Args>(args)...)) {}
+
+  SPECIALIZE_GET_EXCEPTION_NAME(RaftAddServerException)
+};
+
+class RaftBecomeLeaderException final : public utils::BasicException {
+ public:
+  explicit RaftBecomeLeaderException(std::string_view what) noexcept : BasicException(what) {}
+
+  template <class... Args>
+  explicit RaftBecomeLeaderException(fmt::format_string<Args...> fmt, Args &&...args) noexcept
+      : RaftBecomeLeaderException(fmt::format(fmt, std::forward<Args>(args)...)) {}
+
+  SPECIALIZE_GET_EXCEPTION_NAME(RaftBecomeLeaderException)
+};
+
+class RaftCouldNotFindEntryException final : public utils::BasicException {
+ public:
+  explicit RaftCouldNotFindEntryException(std::string_view what) noexcept : BasicException(what) {}
+
+  template <class... Args>
+  explicit RaftCouldNotFindEntryException(fmt::format_string<Args...> fmt, Args &&...args) noexcept
+      : RaftCouldNotFindEntryException(fmt::format(fmt, std::forward<Args>(args)...)) {}
+
+  SPECIALIZE_GET_EXCEPTION_NAME(RaftCouldNotFindEntryException)
+};
+
+class RaftCouldNotParseFlagsException final : public utils::BasicException {
+ public:
+  explicit RaftCouldNotParseFlagsException(std::string_view what) noexcept : BasicException(what) {}
+
+  template <class... Args>
+  explicit RaftCouldNotParseFlagsException(fmt::format_string<Args...> fmt, Args &&...args) noexcept
+      : RaftCouldNotParseFlagsException(fmt::format(fmt, std::forward<Args>(args)...)) {}
+
+  SPECIALIZE_GET_EXCEPTION_NAME(RaftCouldNotParseFlagsException)
 };
 
 }  // namespace memgraph::coordination

src/coordination/include/coordination/coordinator_handlers.hpp

@@ -0,0 +1,48 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#ifdef MG_ENTERPRISE
+
+#include "coordination/coordinator_server.hpp"
+#include "replication_handler/replication_handler.hpp"
+#include "slk/streams.hpp"
+
+namespace memgraph::dbms {
+
+class DbmsHandler;
+
+class CoordinatorHandlers {
+ public:
+  static void Register(memgraph::coordination::CoordinatorServer &server,
+                       replication::ReplicationHandler &replication_handler);
+
+ private:
+  static void PromoteReplicaToMainHandler(replication::ReplicationHandler &replication_handler, slk::Reader *req_reader,
+                                          slk::Builder *res_builder);
+  static void DemoteMainToReplicaHandler(replication::ReplicationHandler &replication_handler, slk::Reader *req_reader,
+                                         slk::Builder *res_builder);
+  static void SwapMainUUIDHandler(replication::ReplicationHandler &replication_handler, slk::Reader *req_reader,
+                                  slk::Builder *res_builder);
+
+  static void UnregisterReplicaHandler(replication::ReplicationHandler &replication_handler, slk::Reader *req_reader,
+                                       slk::Builder *res_builder);
+  static void EnableWritingOnMainHandler(replication::ReplicationHandler &replication_handler, slk::Reader *req_reader,
+                                         slk::Builder *res_builder);
+
+  static void GetInstanceUUIDHandler(replication::ReplicationHandler &replication_handler, slk::Reader *req_reader,
+                                     slk::Builder *res_builder);
+};
+
+}  // namespace memgraph::dbms
+
+#endif

src/coordination/include/coordination/coordinator_instance.hpp

@@ -0,0 +1,60 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#ifdef MG_ENTERPRISE
+
+#include "coordination/coordinator_server.hpp"
+#include "coordination/instance_status.hpp"
+#include "coordination/raft_state.hpp"
+#include "coordination/register_main_replica_coordinator_status.hpp"
+#include "coordination/replication_instance.hpp"
+#include "utils/rw_lock.hpp"
+#include "utils/thread_pool.hpp"
+
+#include <list>
+
+namespace memgraph::coordination {
+
+class CoordinatorInstance {
+ public:
+  CoordinatorInstance();
+
+  [[nodiscard]] auto RegisterReplicationInstance(CoordinatorClientConfig config) -> RegisterInstanceCoordinatorStatus;
+  [[nodiscard]] auto UnregisterReplicationInstance(std::string instance_name) -> UnregisterInstanceCoordinatorStatus;
+
+  [[nodiscard]] auto SetReplicationInstanceToMain(std::string instance_name) -> SetInstanceToMainCoordinatorStatus;
+
+  auto ShowInstances() const -> std::vector<InstanceStatus>;
+
+  auto TryFailover() -> void;
+
+  auto AddCoordinatorInstance(uint32_t raft_server_id, uint32_t raft_port, std::string raft_address) -> void;
+
+  auto GetMainUUID() const -> utils::UUID;
+
+  auto SetMainUUID(utils::UUID new_uuid) -> void;
+
+ private:
+  HealthCheckCallback main_succ_cb_, main_fail_cb_, replica_succ_cb_, replica_fail_cb_;
+
+  // NOTE: Must be std::list because we rely on pointer stability
+  std::list<ReplicationInstance> repl_instances_;
+  mutable utils::RWLock coord_instance_lock_{utils::RWLock::Priority::READ};
+
+  utils::UUID main_uuid_;
+
+  RaftState raft_state_;
+};
+
+}  // namespace memgraph::coordination
+#endif

src/coordination/include/coordination/coordinator_rpc.hpp

@@ -11,6 +11,7 @@
 
 #pragma once
 
+#include "utils/uuid.hpp"
 #ifdef MG_ENTERPRISE
 
 #include "coordination/coordinator_config.hpp"
@@ -26,10 +27,13 @@ struct PromoteReplicaToMainReq {
   static void Load(PromoteReplicaToMainReq *self, memgraph::slk::Reader *reader);
   static void Save(const PromoteReplicaToMainReq &self, memgraph::slk::Builder *builder);
 
-  explicit PromoteReplicaToMainReq(std::vector<CoordinatorClientConfig::ReplicationClientInfo> replication_clients_info)
-      : replication_clients_info(std::move(replication_clients_info)) {}
+  explicit PromoteReplicaToMainReq(const utils::UUID &uuid,
+                                   std::vector<CoordinatorClientConfig::ReplicationClientInfo> replication_clients_info)
+      : main_uuid_(uuid), replication_clients_info(std::move(replication_clients_info)) {}
   PromoteReplicaToMainReq() = default;
 
+  // get uuid here
+  utils::UUID main_uuid_;
   std::vector<CoordinatorClientConfig::ReplicationClientInfo> replication_clients_info;
 };
 
@@ -48,19 +52,146 @@ struct PromoteReplicaToMainRes {
 
 using PromoteReplicaToMainRpc = rpc::RequestResponse<PromoteReplicaToMainReq, PromoteReplicaToMainRes>;
 
+struct DemoteMainToReplicaReq {
+  static const utils::TypeInfo kType;
+  static const utils::TypeInfo &GetTypeInfo() { return kType; }
+
+  static void Load(DemoteMainToReplicaReq *self, memgraph::slk::Reader *reader);
+  static void Save(const DemoteMainToReplicaReq &self, memgraph::slk::Builder *builder);
+
+  explicit DemoteMainToReplicaReq(CoordinatorClientConfig::ReplicationClientInfo replication_client_info)
+      : replication_client_info(std::move(replication_client_info)) {}
+
+  DemoteMainToReplicaReq() = default;
+
+  CoordinatorClientConfig::ReplicationClientInfo replication_client_info;
+};
+
+struct DemoteMainToReplicaRes {
+  static const utils::TypeInfo kType;
+  static const utils::TypeInfo &GetTypeInfo() { return kType; }
+
+  static void Load(DemoteMainToReplicaRes *self, memgraph::slk::Reader *reader);
+  static void Save(const DemoteMainToReplicaRes &self, memgraph::slk::Builder *builder);
+
+  explicit DemoteMainToReplicaRes(bool success) : success(success) {}
+  DemoteMainToReplicaRes() = default;
+
+  bool success;
+};
+
+using DemoteMainToReplicaRpc = rpc::RequestResponse<DemoteMainToReplicaReq, DemoteMainToReplicaRes>;
+
+struct UnregisterReplicaReq {
+  static const utils::TypeInfo kType;
+  static const utils::TypeInfo &GetTypeInfo() { return kType; }
+
+  static void Load(UnregisterReplicaReq *self, memgraph::slk::Reader *reader);
+  static void Save(UnregisterReplicaReq const &self, memgraph::slk::Builder *builder);
+
+  explicit UnregisterReplicaReq(std::string instance_name) : instance_name(std::move(instance_name)) {}
+
+  UnregisterReplicaReq() = default;
+
+  std::string instance_name;
+};
+
+struct UnregisterReplicaRes {
+  static const utils::TypeInfo kType;
+  static const utils::TypeInfo &GetTypeInfo() { return kType; }
+
+  static void Load(UnregisterReplicaRes *self, memgraph::slk::Reader *reader);
+  static void Save(const UnregisterReplicaRes &self, memgraph::slk::Builder *builder);
+
+  explicit UnregisterReplicaRes(bool success) : success(success) {}
+  UnregisterReplicaRes() = default;
+
+  bool success;
+};
+
+using UnregisterReplicaRpc = rpc::RequestResponse<UnregisterReplicaReq, UnregisterReplicaRes>;
+
+struct EnableWritingOnMainReq {
+  static const utils::TypeInfo kType;
+  static const utils::TypeInfo &GetTypeInfo() { return kType; }
+
+  static void Load(EnableWritingOnMainReq *self, memgraph::slk::Reader *reader);
+  static void Save(EnableWritingOnMainReq const &self, memgraph::slk::Builder *builder);
+
+  EnableWritingOnMainReq() = default;
+};
+
+struct EnableWritingOnMainRes {
+  static const utils::TypeInfo kType;
+  static const utils::TypeInfo &GetTypeInfo() { return kType; }
+
+  static void Load(EnableWritingOnMainRes *self, memgraph::slk::Reader *reader);
+  static void Save(EnableWritingOnMainRes const &self, memgraph::slk::Builder *builder);
+
+  explicit EnableWritingOnMainRes(bool success) : success(success) {}
+  EnableWritingOnMainRes() = default;
+
+  bool success;
+};
+
+using EnableWritingOnMainRpc = rpc::RequestResponse<EnableWritingOnMainReq, EnableWritingOnMainRes>;
+
+struct GetInstanceUUIDReq {
+  static const utils::TypeInfo kType;
+  static const utils::TypeInfo &GetTypeInfo() { return kType; }
+
+  static void Load(GetInstanceUUIDReq *self, memgraph::slk::Reader *reader);
+  static void Save(const GetInstanceUUIDReq &self, memgraph::slk::Builder *builder);
+
+  GetInstanceUUIDReq() = default;
+};
+
+struct GetInstanceUUIDRes {
+  static const utils::TypeInfo kType;
+  static const utils::TypeInfo &GetTypeInfo() { return kType; }
+
+  static void Load(GetInstanceUUIDRes *self, memgraph::slk::Reader *reader);
+  static void Save(const GetInstanceUUIDRes &self, memgraph::slk::Builder *builder);
+
+  explicit GetInstanceUUIDRes(std::optional<utils::UUID> uuid) : uuid(uuid) {}
+  GetInstanceUUIDRes() = default;
+
+  std::optional<utils::UUID> uuid;
+};
+
+using GetInstanceUUIDRpc = rpc::RequestResponse<GetInstanceUUIDReq, GetInstanceUUIDRes>;
+
 }  // namespace memgraph::coordination
 
 // SLK serialization declarations
 namespace memgraph::slk {
 
+// PromoteReplicaToMainRpc
 void Save(const memgraph::coordination::PromoteReplicaToMainRes &self, memgraph::slk::Builder *builder);
-
 void Load(memgraph::coordination::PromoteReplicaToMainRes *self, memgraph::slk::Reader *reader);
-
 void Save(const memgraph::coordination::PromoteReplicaToMainReq &self, memgraph::slk::Builder *builder);
-
 void Load(memgraph::coordination::PromoteReplicaToMainReq *self, memgraph::slk::Reader *reader);
 
+// DemoteMainToReplicaRpc
+void Save(const memgraph::coordination::DemoteMainToReplicaRes &self, memgraph::slk::Builder *builder);
+void Load(memgraph::coordination::DemoteMainToReplicaRes *self, memgraph::slk::Reader *reader);
+void Save(const memgraph::coordination::DemoteMainToReplicaReq &self, memgraph::slk::Builder *builder);
+void Load(memgraph::coordination::DemoteMainToReplicaReq *self, memgraph::slk::Reader *reader);
+
+// GetInstanceUUIDRpc
+void Save(const memgraph::coordination::GetInstanceUUIDReq &self, memgraph::slk::Builder *builder);
+void Load(memgraph::coordination::GetInstanceUUIDReq *self, memgraph::slk::Reader *reader);
+void Save(const memgraph::coordination::GetInstanceUUIDRes &self, memgraph::slk::Builder *builder);
+void Load(memgraph::coordination::GetInstanceUUIDRes *self, memgraph::slk::Reader *reader);
+// UnregisterReplicaRpc
+void Save(memgraph::coordination::UnregisterReplicaRes const &self, memgraph::slk::Builder *builder);
+void Load(memgraph::coordination::UnregisterReplicaRes *self, memgraph::slk::Reader *reader);
+void Save(memgraph::coordination::UnregisterReplicaReq const &self, memgraph::slk::Builder *builder);
+void Load(memgraph::coordination::UnregisterReplicaReq *self, memgraph::slk::Reader *reader);
+
+void Save(memgraph::coordination::EnableWritingOnMainRes const &self, memgraph::slk::Builder *builder);
+void Load(memgraph::coordination::EnableWritingOnMainRes *self, memgraph::slk::Reader *reader);
+
 }  // namespace memgraph::slk
 
 #endif

src/coordination/include/coordination/coordinator_state.hpp

@@ -13,81 +13,44 @@
 
 #ifdef MG_ENTERPRISE
 
-#include "coordination/coordinator_client.hpp"
-#include "coordination/coordinator_entity_info.hpp"
+#include "coordination/coordinator_instance.hpp"
 #include "coordination/coordinator_server.hpp"
-#include "rpc/server.hpp"
-#include "utils/result.hpp"
-#include "utils/rw_spin_lock.hpp"
-#include "utils/synchronized.hpp"
+#include "coordination/instance_status.hpp"
+#include "coordination/register_main_replica_coordinator_status.hpp"
 
-#include <list>
 #include <variant>
 
 namespace memgraph::coordination {
 
-enum class RegisterMainReplicaCoordinatorStatus : uint8_t {
-  NAME_EXISTS,
-  END_POINT_EXISTS,
-  COULD_NOT_BE_PERSISTED,
-  NOT_COORDINATOR,
-  SUCCESS
-};
-
-enum class DoFailoverStatus : uint8_t { SUCCESS, ALL_REPLICAS_DOWN, MAIN_ALIVE, CLUSTER_UNINITIALIZED };
-
 class CoordinatorState {
  public:
   CoordinatorState();
   ~CoordinatorState() = default;
 
-  CoordinatorState(const CoordinatorState &) = delete;
-  CoordinatorState &operator=(const CoordinatorState &) = delete;
+  CoordinatorState(CoordinatorState const &) = delete;
+  CoordinatorState &operator=(CoordinatorState const &) = delete;
 
-  CoordinatorState(CoordinatorState &&other) noexcept : data_(std::move(other.data_)) {}
+  CoordinatorState(CoordinatorState &&) noexcept = delete;
+  CoordinatorState &operator=(CoordinatorState &&) noexcept = delete;
 
-  CoordinatorState &operator=(CoordinatorState &&other) noexcept {
-    if (this == &other) {
-      return *this;
-    }
-    data_ = std::move(other.data_);
-    return *this;
-  }
+  [[nodiscard]] auto RegisterReplicationInstance(CoordinatorClientConfig config) -> RegisterInstanceCoordinatorStatus;
+  [[nodiscard]] auto UnregisterReplicationInstance(std::string instance_name) -> UnregisterInstanceCoordinatorStatus;
 
-  auto RegisterReplica(const CoordinatorClientConfig &config)
-      -> utils::BasicResult<RegisterMainReplicaCoordinatorStatus, CoordinatorClient *>;
+  [[nodiscard]] auto SetReplicationInstanceToMain(std::string instance_name) -> SetInstanceToMainCoordinatorStatus;
 
-  auto RegisterMain(const CoordinatorClientConfig &config)
-      -> utils::BasicResult<RegisterMainReplicaCoordinatorStatus, CoordinatorClient *>;
+  auto ShowInstances() const -> std::vector<InstanceStatus>;
 
-  auto ShowReplicas() const -> std::vector<CoordinatorEntityInfo>;
+  auto AddCoordinatorInstance(uint32_t raft_server_id, uint32_t raft_port, std::string raft_address) -> void;
 
-  auto PingReplicas() const -> std::unordered_map<std::string_view, bool>;
-
-  auto ShowMain() const -> std::optional<CoordinatorEntityInfo>;
-
-  auto PingMain() const -> std::optional<CoordinatorEntityHealthInfo>;
-
-  // The client code must check that the server exists before calling this method.
+  // NOTE: The client code must check that the server exists before calling this method.
   auto GetCoordinatorServer() const -> CoordinatorServer &;
 
-  auto DoFailover() -> DoFailoverStatus;
-
  private:
-  // TODO: Data is not thread safe
-
-  // Coordinator stores registered replicas and main
-  struct CoordinatorData {
-    std::list<CoordinatorClient> registered_replicas_;
-    std::unique_ptr<CoordinatorClient> registered_main_;
-  };
-
-  // Data which each main and replica stores
   struct CoordinatorMainReplicaData {
     std::unique_ptr<CoordinatorServer> coordinator_server_;
   };
 
-  std::variant<CoordinatorData, CoordinatorMainReplicaData> data_;
+  std::variant<CoordinatorInstance, CoordinatorMainReplicaData> data_;
 };
 
 }  // namespace memgraph::coordination

src/coordination/include/coordination/instance_status.hpp

@@ -0,0 +1,34 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#ifdef MG_ENTERPRISE
+
+#include "io/network/endpoint.hpp"
+
+#include <string_view>
+
+namespace memgraph::coordination {
+
+// TODO: (andi) For phase IV. Some instances won't have raft_socket_address, coord_socket_address, replication_role and
+// cluster role... At the end, all instances will have everything.
+struct InstanceStatus {
+  std::string instance_name;
+  std::string raft_socket_address;
+  std::string coord_socket_address;
+  std::string cluster_role;
+  bool is_alive;
+};
+
+}  // namespace memgraph::coordination
+
+#endif

src/coordination/include/coordination/raft_state.hpp

@@ -0,0 +1,79 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#ifdef MG_ENTERPRISE
+
+#include <flags/replication.hpp>
+
+#include <libnuraft/nuraft.hxx>
+
+namespace memgraph::coordination {
+
+using BecomeLeaderCb = std::function<void()>;
+using BecomeFollowerCb = std::function<void()>;
+
+using nuraft::buffer;
+using nuraft::logger;
+using nuraft::ptr;
+using nuraft::raft_launcher;
+using nuraft::raft_server;
+using nuraft::srv_config;
+using nuraft::state_machine;
+using nuraft::state_mgr;
+using raft_result = nuraft::cmd_result<ptr<buffer>>;
+
+class RaftState {
+ private:
+  explicit RaftState(BecomeLeaderCb become_leader_cb, BecomeFollowerCb become_follower_cb, uint32_t raft_server_id,
+                     uint32_t raft_port, std::string raft_address);
+
+  auto InitRaftServer() -> void;
+
+ public:
+  RaftState() = delete;
+  RaftState(RaftState const &other) = default;
+  RaftState &operator=(RaftState const &other) = default;
+  RaftState(RaftState &&other) noexcept = default;
+  RaftState &operator=(RaftState &&other) noexcept = default;
+  ~RaftState();
+
+  static auto MakeRaftState(BecomeLeaderCb become_leader_cb, BecomeFollowerCb become_follower_cb) -> RaftState;
+
+  auto InstanceName() const -> std::string;
+  auto RaftSocketAddress() const -> std::string;
+
+  auto AddCoordinatorInstance(uint32_t raft_server_id, uint32_t raft_port, std::string raft_address) -> void;
+  auto GetAllCoordinators() const -> std::vector<ptr<srv_config>>;
+
+  auto RequestLeadership() -> bool;
+  auto IsLeader() const -> bool;
+
+  auto AppendRegisterReplicationInstance(std::string const &instance) -> ptr<raft_result>;
+
+  // TODO: (andi) I think variables below can be abstracted
+  uint32_t raft_server_id_;
+  uint32_t raft_port_;
+  std::string raft_address_;
+
+  ptr<state_machine> state_machine_;
+  ptr<state_mgr> state_manager_;
+  ptr<raft_server> raft_server_;
+  ptr<logger> logger_;
+  raft_launcher launcher_;
+
+  BecomeLeaderCb become_leader_cb_;
+  BecomeFollowerCb become_follower_cb_;
+};
+
+}  // namespace memgraph::coordination
+#endif

src/coordination/include/coordination/register_main_replica_coordinator_status.hpp

@@ -0,0 +1,50 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#ifdef MG_ENTERPRISE
+
+#include <cstdint>
+
+namespace memgraph::coordination {
+
+enum class RegisterInstanceCoordinatorStatus : uint8_t {
+  NAME_EXISTS,
+  ENDPOINT_EXISTS,
+  NOT_COORDINATOR,
+  RPC_FAILED,
+  NOT_LEADER,
+  RAFT_COULD_NOT_ACCEPT,
+  RAFT_COULD_NOT_APPEND,
+  SUCCESS
+};
+
+enum class UnregisterInstanceCoordinatorStatus : uint8_t {
+  NO_INSTANCE_WITH_NAME,
+  IS_MAIN,
+  NOT_COORDINATOR,
+  NOT_LEADER,
+  RPC_FAILED,
+  SUCCESS,
+};
+
+enum class SetInstanceToMainCoordinatorStatus : uint8_t {
+  NO_INSTANCE_WITH_NAME,
+  MAIN_ALREADY_EXISTS,
+  NOT_COORDINATOR,
+  SUCCESS,
+  COULD_NOT_PROMOTE_TO_MAIN,
+  SWAP_UUID_FAILED
+};
+
+}  // namespace memgraph::coordination
+#endif

src/coordination/include/coordination/replication_instance.hpp

@@ -0,0 +1,99 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#ifdef MG_ENTERPRISE
+
+#include "coordination/coordinator_client.hpp"
+#include "coordination/coordinator_exceptions.hpp"
+#include "replication_coordination_glue/role.hpp"
+
+#include <libnuraft/nuraft.hxx>
+#include "utils/result.hpp"
+#include "utils/uuid.hpp"
+
+namespace memgraph::coordination {
+
+class CoordinatorInstance;
+
+class ReplicationInstance {
+ public:
+  ReplicationInstance(CoordinatorInstance *peer, CoordinatorClientConfig config, HealthCheckCallback succ_cb,
+                      HealthCheckCallback fail_cb);
+
+  ReplicationInstance(ReplicationInstance const &other) = delete;
+  ReplicationInstance &operator=(ReplicationInstance const &other) = delete;
+  ReplicationInstance(ReplicationInstance &&other) noexcept = delete;
+  ReplicationInstance &operator=(ReplicationInstance &&other) noexcept = delete;
+  ~ReplicationInstance() = default;
+
+  auto OnSuccessPing() -> void;
+  auto OnFailPing() -> bool;
+  auto IsReadyForUUIDPing() -> bool;
+
+  void UpdateReplicaLastResponseUUID();
+
+  auto IsAlive() const -> bool;
+
+  auto InstanceName() const -> std::string;
+  auto SocketAddress() const -> std::string;
+
+  auto IsReplica() const -> bool;
+  auto IsMain() const -> bool;
+
+  auto PromoteToMain(utils::UUID uuid, ReplicationClientsInfo repl_clients_info, HealthCheckCallback main_succ_cb,
+                     HealthCheckCallback main_fail_cb) -> bool;
+  auto DemoteToReplica(HealthCheckCallback replica_succ_cb, HealthCheckCallback replica_fail_cb) -> bool;
+
+  auto StartFrequentCheck() -> void;
+  auto StopFrequentCheck() -> void;
+  auto PauseFrequentCheck() -> void;
+  auto ResumeFrequentCheck() -> void;
+
+  auto ReplicationClientInfo() const -> ReplClientInfo;
+
+  auto EnsureReplicaHasCorrectMainUUID(utils::UUID const &curr_main_uuid) -> bool;
+
+  auto SendSwapAndUpdateUUID(const utils::UUID &new_main_uuid) -> bool;
+  auto SendUnregisterReplicaRpc(std::string const &instance_name) -> bool;
+
+
+  auto SendGetInstanceUUID() -> utils::BasicResult<coordination::GetInstanceUUIDError, std::optional<utils::UUID>>;
+  auto GetClient() -> CoordinatorClient &;
+
+  auto EnableWritingOnMain() -> bool;
+
+  auto SetNewMainUUID(utils::UUID const &main_uuid) -> void;
+  auto ResetMainUUID() -> void;
+  auto GetMainUUID() const -> const std::optional<utils::UUID> &;
+
+ private:
+  CoordinatorClient client_;
+  replication_coordination_glue::ReplicationRole replication_role_;
+  std::chrono::system_clock::time_point last_response_time_{};
+  bool is_alive_{false};
+  std::chrono::system_clock::time_point last_check_of_uuid_{};
+
+  // for replica this is main uuid of current main
+  // for "main" main this same as in CoordinatorData
+  // it is set to nullopt when replica is down
+  // TLDR; when replica is down and comes back up we reset uuid of main replica is listening to
+  // so we need to send swap uuid again
+  std::optional<utils::UUID> main_uuid_;
+
+  friend bool operator==(ReplicationInstance const &first, ReplicationInstance const &second) {
+    return first.client_ == second.client_ && first.replication_role_ == second.replication_role_;
+  }
+};
+
+}  // namespace memgraph::coordination
+#endif

src/coordination/include/coordination/rpc_errors.hpp

@@ -9,26 +9,6 @@
 // by the Apache License, Version 2.0, included in the file
 // licenses/APL.txt.
 
-#pragma once
-
-#ifdef MG_ENTERPRISE
-
-#include "io/network/endpoint.hpp"
-
-#include <string>
-
 namespace memgraph::coordination {
-
-struct CoordinatorEntityInfo {
-  std::string_view name;
-  const io::network::Endpoint &endpoint;
-};
-
-struct CoordinatorEntityHealthInfo {
-  std::string_view name;
-  bool alive;
-};
-
+enum class GetInstanceUUIDError { NO_RESPONSE, RPC_EXCEPTION };
 }  // namespace memgraph::coordination
-
-#endif

src/coordination/include/nuraft/coordinator_log_store.hpp

@@ -0,0 +1,70 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#ifdef MG_ENTERPRISE
+
+#include <libnuraft/nuraft.hxx>
+
+namespace memgraph::coordination {
+
+using nuraft::buffer;
+using nuraft::int32;
+using nuraft::int64;
+using nuraft::log_entry;
+using nuraft::log_store;
+using nuraft::ptr;
+using nuraft::raft_server;
+
+class CoordinatorLogStore : public log_store {
+ public:
+  CoordinatorLogStore();
+  CoordinatorLogStore(CoordinatorLogStore const &) = delete;
+  CoordinatorLogStore &operator=(CoordinatorLogStore const &) = delete;
+  CoordinatorLogStore(CoordinatorLogStore &&) = delete;
+  CoordinatorLogStore &operator=(CoordinatorLogStore &&) = delete;
+  ~CoordinatorLogStore() override;
+
+  ulong next_slot() const override;
+
+  ulong start_index() const override;
+
+  ptr<log_entry> last_entry() const override;
+
+  ulong append(ptr<log_entry> &entry) override;
+
+  void write_at(ulong index, ptr<log_entry> &entry) override;
+
+  ptr<std::vector<ptr<log_entry>>> log_entries(ulong start, ulong end) override;
+
+  ptr<log_entry> entry_at(ulong index) override;
+
+  ulong term_at(ulong index) override;
+
+  ptr<buffer> pack(ulong index, int32 cnt) override;
+
+  void apply_pack(ulong index, buffer &pack) override;
+
+  bool compact(ulong last_log_index) override;
+
+  bool flush() override;
+
+ private:
+  auto FindOrDefault_(ulong index) const -> ptr<log_entry>;
+
+  std::map<ulong, ptr<log_entry>> logs_;
+  mutable std::mutex logs_lock_;
+  std::atomic<ulong> start_idx_;
+};
+
+}  // namespace memgraph::coordination
+#endif

src/coordination/include/nuraft/coordinator_state_machine.hpp

@@ -0,0 +1,76 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#ifdef MG_ENTERPRISE
+
+#include <spdlog/spdlog.h>
+#include <libnuraft/nuraft.hxx>
+
+namespace memgraph::coordination {
+
+using nuraft::async_result;
+using nuraft::buffer;
+using nuraft::buffer_serializer;
+using nuraft::cluster_config;
+using nuraft::int32;
+using nuraft::ptr;
+using nuraft::snapshot;
+using nuraft::state_machine;
+
+class CoordinatorStateMachine : public state_machine {
+ public:
+  CoordinatorStateMachine() = default;
+  CoordinatorStateMachine(CoordinatorStateMachine const &) = delete;
+  CoordinatorStateMachine &operator=(CoordinatorStateMachine const &) = delete;
+  CoordinatorStateMachine(CoordinatorStateMachine &&) = delete;
+  CoordinatorStateMachine &operator=(CoordinatorStateMachine &&) = delete;
+  ~CoordinatorStateMachine() override {}
+
+  static auto EncodeRegisterReplicationInstance(const std::string &name) -> ptr<buffer>;
+
+  static auto DecodeRegisterReplicationInstance(buffer &data) -> std::string;
+
+  auto pre_commit(ulong log_idx, buffer &data) -> ptr<buffer> override;
+
+  auto commit(ulong log_idx, buffer &data) -> ptr<buffer> override;
+
+  auto commit_config(ulong log_idx, ptr<cluster_config> & /*new_conf*/) -> void override;
+
+  auto rollback(ulong log_idx, buffer &data) -> void override;
+
+  auto read_logical_snp_obj(snapshot & /*snapshot*/, void *& /*user_snp_ctx*/, ulong /*obj_id*/, ptr<buffer> &data_out,
+                            bool &is_last_obj) -> int override;
+
+  auto save_logical_snp_obj(snapshot &s, ulong &obj_id, buffer & /*data*/, bool /*is_first_obj*/, bool /*is_last_obj*/)
+      -> void override;
+
+  auto apply_snapshot(snapshot &s) -> bool override;
+
+  auto free_user_snp_ctx(void *&user_snp_ctx) -> void override;
+
+  auto last_snapshot() -> ptr<snapshot> override;
+
+  auto last_commit_index() -> ulong override;
+
+  auto create_snapshot(snapshot &s, async_result<bool>::handler_type &when_done) -> void override;
+
+ private:
+  std::atomic<uint64_t> last_committed_idx_{0};
+
+  ptr<snapshot> last_snapshot_;
+
+  std::mutex last_snapshot_lock_;
+};
+
+}  // namespace memgraph::coordination
+#endif

src/coordination/include/nuraft/coordinator_state_manager.hpp

@@ -0,0 +1,66 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#ifdef MG_ENTERPRISE
+
+#include "nuraft/coordinator_log_store.hpp"
+
+#include <spdlog/spdlog.h>
+#include <libnuraft/nuraft.hxx>
+
+namespace memgraph::coordination {
+
+using nuraft::cluster_config;
+using nuraft::cs_new;
+using nuraft::srv_config;
+using nuraft::srv_state;
+using nuraft::state_mgr;
+
+class CoordinatorStateManager : public state_mgr {
+ public:
+  explicit CoordinatorStateManager(int srv_id, std::string const &endpoint);
+
+  CoordinatorStateManager(CoordinatorStateManager const &) = delete;
+  CoordinatorStateManager &operator=(CoordinatorStateManager const &) = delete;
+  CoordinatorStateManager(CoordinatorStateManager &&) = delete;
+  CoordinatorStateManager &operator=(CoordinatorStateManager &&) = delete;
+
+  ~CoordinatorStateManager() override = default;
+
+  auto load_config() -> ptr<cluster_config> override;
+
+  auto save_config(cluster_config const &config) -> void override;
+
+  auto save_state(srv_state const &state) -> void override;
+
+  auto read_state() -> ptr<srv_state> override;
+
+  auto load_log_store() -> ptr<log_store> override;
+
+  auto server_id() -> int32 override;
+
+  auto system_exit(int exit_code) -> void override;
+
+  auto GetSrvConfig() const -> ptr<srv_config>;
+
+ private:
+  int my_id_;
+  std::string my_endpoint_;
+  ptr<CoordinatorLogStore> cur_log_store_;
+  ptr<srv_config> my_srv_config_;
+  ptr<cluster_config> cluster_config_;
+  ptr<srv_state> saved_state_;
+};
+
+}  // namespace memgraph::coordination
+#endif

src/coordination/raft_state.cpp

@@ -0,0 +1,140 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#ifdef MG_ENTERPRISE
+
+#include "coordination/raft_state.hpp"
+
+#include "coordination/coordinator_exceptions.hpp"
+#include "nuraft/coordinator_state_machine.hpp"
+#include "nuraft/coordinator_state_manager.hpp"
+#include "utils/counter.hpp"
+
+namespace memgraph::coordination {
+
+using nuraft::asio_service;
+using nuraft::cb_func;
+using nuraft::CbReturnCode;
+using nuraft::cmd_result;
+using nuraft::cs_new;
+using nuraft::ptr;
+using nuraft::raft_params;
+using nuraft::raft_server;
+using nuraft::srv_config;
+using raft_result = cmd_result<ptr<buffer>>;
+
+RaftState::RaftState(BecomeLeaderCb become_leader_cb, BecomeFollowerCb become_follower_cb, uint32_t raft_server_id,
+                     uint32_t raft_port, std::string raft_address)
+    : raft_server_id_(raft_server_id),
+      raft_port_(raft_port),
+      raft_address_(std::move(raft_address)),
+      state_machine_(cs_new<CoordinatorStateMachine>()),
+      state_manager_(
+          cs_new<CoordinatorStateManager>(raft_server_id_, raft_address_ + ":" + std::to_string(raft_port_))),
+      logger_(nullptr),
+      become_leader_cb_(std::move(become_leader_cb)),
+      become_follower_cb_(std::move(become_follower_cb)) {}
+
+auto RaftState::InitRaftServer() -> void {
+  asio_service::options asio_opts;
+  asio_opts.thread_pool_size_ = 1;  // TODO: (andi) Improve this
+
+  raft_params params;
+  params.heart_beat_interval_ = 100;
+  params.election_timeout_lower_bound_ = 200;
+  params.election_timeout_upper_bound_ = 400;
+  // 5 logs are preserved before the last snapshot
+  params.reserved_log_items_ = 5;
+  // Create snapshot for every 5 log appends
+  params.snapshot_distance_ = 5;
+  params.client_req_timeout_ = 3000;
+  params.return_method_ = raft_params::blocking;
+
+  raft_server::init_options init_opts;
+  init_opts.raft_callback_ = [this](cb_func::Type event_type, cb_func::Param *param) -> nuraft::CbReturnCode {
+    if (event_type == cb_func::BecomeLeader) {
+      spdlog::info("Node {} became leader", param->leaderId);
+      become_leader_cb_();
+    } else if (event_type == cb_func::BecomeFollower) {
+      spdlog::info("Node {} became follower", param->myId);
+      become_follower_cb_();
+    }
+    return CbReturnCode::Ok;
+  };
+
+  raft_launcher launcher;
+
+  raft_server_ = launcher.init(state_machine_, state_manager_, logger_, static_cast<int>(raft_port_), asio_opts, params,
+                               init_opts);
+
+  if (!raft_server_) {
+    throw RaftServerStartException("Failed to launch raft server on {}:{}", raft_address_, raft_port_);
+  }
+
+  auto maybe_stop = utils::ResettableCounter<20>();
+  do {
+    if (raft_server_->is_initialized()) {
+      return;
+    }
+    std::this_thread::sleep_for(std::chrono::milliseconds(250));
+  } while (!maybe_stop());
+
+  throw RaftServerStartException("Failed to initialize raft server on {}:{}", raft_address_, raft_port_);
+}
+
+auto RaftState::MakeRaftState(BecomeLeaderCb become_leader_cb, BecomeFollowerCb become_follower_cb) -> RaftState {
+  uint32_t raft_server_id{0};
+  uint32_t raft_port{0};
+  try {
+    raft_server_id = FLAGS_raft_server_id;
+    raft_port = FLAGS_raft_server_port;
+  } catch (std::exception const &e) {
+    throw RaftCouldNotParseFlagsException("Failed to parse flags: {}", e.what());
+  }
+
+  auto raft_state =
+      RaftState(std::move(become_leader_cb), std::move(become_follower_cb), raft_server_id, raft_port, "127.0.0.1");
+  raft_state.InitRaftServer();
+  return raft_state;
+}
+
+RaftState::~RaftState() { launcher_.shutdown(); }
+
+auto RaftState::InstanceName() const -> std::string { return "coordinator_" + std::to_string(raft_server_id_); }
+
+auto RaftState::RaftSocketAddress() const -> std::string { return raft_address_ + ":" + std::to_string(raft_port_); }
+
+auto RaftState::AddCoordinatorInstance(uint32_t raft_server_id, uint32_t raft_port, std::string raft_address) -> void {
+  auto const endpoint = raft_address + ":" + std::to_string(raft_port);
+  srv_config const srv_config_to_add(static_cast<int>(raft_server_id), endpoint);
+  if (!raft_server_->add_srv(srv_config_to_add)->get_accepted()) {
+    throw RaftAddServerException("Failed to add server {} to the cluster", endpoint);
+  }
+  spdlog::info("Request to add server {} to the cluster accepted", endpoint);
+}
+
+auto RaftState::GetAllCoordinators() const -> std::vector<ptr<srv_config>> {
+  std::vector<ptr<srv_config>> all_srv_configs;
+  raft_server_->get_srv_config_all(all_srv_configs);
+  return all_srv_configs;
+}
+
+auto RaftState::IsLeader() const -> bool { return raft_server_->is_leader(); }
+
+auto RaftState::RequestLeadership() -> bool { return raft_server_->is_leader() || raft_server_->request_leadership(); }
+
+auto RaftState::AppendRegisterReplicationInstance(std::string const &instance) -> ptr<raft_result> {
+  auto new_log = CoordinatorStateMachine::EncodeRegisterReplicationInstance(instance);
+  return raft_server_->append_entries({new_log});
+}
+
+}  // namespace memgraph::coordination
+#endif

src/coordination/replication_instance.cpp

@@ -0,0 +1,138 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#ifdef MG_ENTERPRISE
+
+#include "coordination/replication_instance.hpp"
+
+#include "replication_coordination_glue/handler.hpp"
+#include "utils/result.hpp"
+
+namespace memgraph::coordination {
+
+ReplicationInstance::ReplicationInstance(CoordinatorInstance *peer, CoordinatorClientConfig config,
+                                         HealthCheckCallback succ_cb, HealthCheckCallback fail_cb)
+    : client_(peer, std::move(config), std::move(succ_cb), std::move(fail_cb)),
+      replication_role_(replication_coordination_glue::ReplicationRole::REPLICA) {
+  if (!client_.DemoteToReplica()) {
+    throw CoordinatorRegisterInstanceException("Failed to demote instance {} to replica", client_.InstanceName());
+  }
+
+  client_.StartFrequentCheck();
+}
+
+auto ReplicationInstance::OnSuccessPing() -> void {
+  last_response_time_ = std::chrono::system_clock::now();
+  is_alive_ = true;
+}
+
+auto ReplicationInstance::OnFailPing() -> bool {
+  auto elapsed_time = std::chrono::system_clock::now() - last_response_time_;
+  is_alive_ = elapsed_time < client_.InstanceDownTimeoutSec();
+  return is_alive_;
+}
+
+auto ReplicationInstance::IsReadyForUUIDPing() -> bool {
+  return std::chrono::duration_cast<std::chrono::seconds>(std::chrono::system_clock::now() - last_check_of_uuid_) >
+         client_.InstanceGetUUIDFrequencySec();
+}
+
+auto ReplicationInstance::InstanceName() const -> std::string { return client_.InstanceName(); }
+auto ReplicationInstance::SocketAddress() const -> std::string { return client_.SocketAddress(); }
+auto ReplicationInstance::IsAlive() const -> bool { return is_alive_; }
+
+auto ReplicationInstance::IsReplica() const -> bool {
+  return replication_role_ == replication_coordination_glue::ReplicationRole::REPLICA;
+}
+auto ReplicationInstance::IsMain() const -> bool {
+  return replication_role_ == replication_coordination_glue::ReplicationRole::MAIN;
+}
+
+auto ReplicationInstance::PromoteToMain(utils::UUID new_uuid, ReplicationClientsInfo repl_clients_info,
+                                        HealthCheckCallback main_succ_cb, HealthCheckCallback main_fail_cb) -> bool {
+  if (!client_.SendPromoteReplicaToMainRpc(new_uuid, std::move(repl_clients_info))) {
+    return false;
+  }
+
+  replication_role_ = replication_coordination_glue::ReplicationRole::MAIN;
+  main_uuid_ = new_uuid;
+  client_.SetCallbacks(std::move(main_succ_cb), std::move(main_fail_cb));
+
+  return true;
+}
+
+auto ReplicationInstance::DemoteToReplica(HealthCheckCallback replica_succ_cb, HealthCheckCallback replica_fail_cb)
+    -> bool {
+  if (!client_.DemoteToReplica()) {
+    return false;
+  }
+
+  replication_role_ = replication_coordination_glue::ReplicationRole::REPLICA;
+  client_.SetCallbacks(std::move(replica_succ_cb), std::move(replica_fail_cb));
+
+  return true;
+}
+
+auto ReplicationInstance::StartFrequentCheck() -> void { client_.StartFrequentCheck(); }
+auto ReplicationInstance::StopFrequentCheck() -> void { client_.StopFrequentCheck(); }
+auto ReplicationInstance::PauseFrequentCheck() -> void { client_.PauseFrequentCheck(); }
+auto ReplicationInstance::ResumeFrequentCheck() -> void { client_.ResumeFrequentCheck(); }
+
+auto ReplicationInstance::ReplicationClientInfo() const -> CoordinatorClientConfig::ReplicationClientInfo {
+  return client_.ReplicationClientInfo();
+}
+
+auto ReplicationInstance::GetClient() -> CoordinatorClient & { return client_; }
+
+auto ReplicationInstance::SetNewMainUUID(utils::UUID const &main_uuid) -> void { main_uuid_ = main_uuid; }
+auto ReplicationInstance::ResetMainUUID() -> void { main_uuid_ = std::nullopt; }
+auto ReplicationInstance::GetMainUUID() const -> std::optional<utils::UUID> const & { return main_uuid_; }
+
+auto ReplicationInstance::EnsureReplicaHasCorrectMainUUID(utils::UUID const &curr_main_uuid) -> bool {
+  if (!IsReadyForUUIDPing()) {
+    return true;
+  }
+  auto res = SendGetInstanceUUID();
+  if (res.HasError()) {
+    return false;
+  }
+  UpdateReplicaLastResponseUUID();
+
+  if (res.GetValue().has_value() && res.GetValue().value() == curr_main_uuid) {
+    return true;
+  }
+
+  return SendSwapAndUpdateUUID(curr_main_uuid);
+}
+
+auto ReplicationInstance::SendSwapAndUpdateUUID(const utils::UUID &new_main_uuid) -> bool {
+  if (!replication_coordination_glue::SendSwapMainUUIDRpc(client_.RpcClient(), new_main_uuid)) {
+    return false;
+  }
+  SetNewMainUUID(new_main_uuid);
+  return true;
+}
+
+auto ReplicationInstance::SendUnregisterReplicaRpc(std::string const &instance_name) -> bool {
+  return client_.SendUnregisterReplicaRpc(instance_name);
+}
+
+auto ReplicationInstance::EnableWritingOnMain() -> bool { return client_.SendEnableWritingOnMainRpc(); }
+
+auto ReplicationInstance::SendGetInstanceUUID()
+    -> utils::BasicResult<coordination::GetInstanceUUIDError, std::optional<utils::UUID>> {
+  return client_.SendGetInstanceUUIDRpc();
+}
+
+void ReplicationInstance::UpdateReplicaLastResponseUUID() { last_check_of_uuid_ = std::chrono::system_clock::now(); }
+
+}  // namespace memgraph::coordination
+#endif

src/dbms/CMakeLists.txt

@@ -1,2 +1,10 @@
-add_library(mg-dbms STATIC dbms_handler.cpp database.cpp replication_handler.cpp coordinator_handler.cpp replication_client.cpp inmemory/replication_handlers.cpp coordinator_handlers.cpp)
-target_link_libraries(mg-dbms mg-utils mg-storage-v2 mg-query mg-replication mg-coordination)
+add_library(mg-dbms STATIC
+        dbms_handler.cpp
+        database.cpp
+        coordinator_handler.cpp
+        inmemory/replication_handlers.cpp
+        replication_handlers.cpp
+        rpc.cpp
+
+)
+target_link_libraries(mg-dbms mg-utils mg-storage-v2 mg-query mg-auth mg-replication mg-coordination)

src/dbms/constants.hpp

@@ -16,10 +16,4 @@ namespace memgraph::dbms {
 constexpr std::string_view kDefaultDB = "memgraph";        //!< Name of the default database
 constexpr std::string_view kMultiTenantDir = "databases";  //!< Name of the multi-tenant directory
 
-#ifdef MG_EXPERIMENTAL_REPLICATION_MULTITENANCY
-constexpr bool allow_mt_repl = true;
-#else
-constexpr bool allow_mt_repl = false;
-#endif
-
 }  // namespace memgraph::dbms

src/dbms/coordinator_handler.cpp

@@ -13,85 +13,35 @@
 
 #include "dbms/coordinator_handler.hpp"
 
-#include "dbms/dbms_handler.hpp"
+#include "coordination/register_main_replica_coordinator_status.hpp"
 
 namespace memgraph::dbms {
 
-CoordinatorHandler::CoordinatorHandler(DbmsHandler &dbms_handler) : dbms_handler_(dbms_handler) {}
+CoordinatorHandler::CoordinatorHandler(coordination::CoordinatorState &coordinator_state)
+    : coordinator_state_(coordinator_state) {}
 
-auto CoordinatorHandler::RegisterReplicaOnCoordinator(const memgraph::coordination::CoordinatorClientConfig &config)
-    -> utils::BasicResult<RegisterMainReplicaCoordinatorStatus> {
-  auto instance_client = dbms_handler_.CoordinatorState().RegisterReplica(config);
-  using repl_status = memgraph::coordination::RegisterMainReplicaCoordinatorStatus;
-  using dbms_status = memgraph::dbms::RegisterMainReplicaCoordinatorStatus;
-  if (instance_client.HasError()) {
-    switch (instance_client.GetError()) {
-      case memgraph::coordination::RegisterMainReplicaCoordinatorStatus::NOT_COORDINATOR:
-        MG_ASSERT(false, "Only coordinator instance can register main and replica!");
-        return {};
-      case repl_status::NAME_EXISTS:
-        return dbms_status::NAME_EXISTS;
-      case repl_status::END_POINT_EXISTS:
-        return dbms_status::END_POINT_EXISTS;
-      case repl_status::COULD_NOT_BE_PERSISTED:
-        return dbms_status::COULD_NOT_BE_PERSISTED;
-      case repl_status::SUCCESS:
-        break;
-    }
-  }
-
-  instance_client.GetValue()->StartFrequentCheck();
-  return {};
+auto CoordinatorHandler::RegisterReplicationInstance(memgraph::coordination::CoordinatorClientConfig config)
+    -> coordination::RegisterInstanceCoordinatorStatus {
+  return coordinator_state_.RegisterReplicationInstance(config);
 }
 
-auto CoordinatorHandler::RegisterMainOnCoordinator(const memgraph::coordination::CoordinatorClientConfig &config)
-    -> utils::BasicResult<RegisterMainReplicaCoordinatorStatus> {
-  auto instance_client = dbms_handler_.CoordinatorState().RegisterMain(config);
-  if (instance_client.HasError()) switch (instance_client.GetError()) {
-      case memgraph::coordination::RegisterMainReplicaCoordinatorStatus::NOT_COORDINATOR:
-        MG_ASSERT(false, "Only coordinator instance can register main and replica!");
-      case memgraph::coordination::RegisterMainReplicaCoordinatorStatus::NAME_EXISTS:
-        return memgraph::dbms::RegisterMainReplicaCoordinatorStatus::NAME_EXISTS;
-      case memgraph::coordination::RegisterMainReplicaCoordinatorStatus::END_POINT_EXISTS:
-        return memgraph::dbms::RegisterMainReplicaCoordinatorStatus::END_POINT_EXISTS;
-      case memgraph::coordination::RegisterMainReplicaCoordinatorStatus::COULD_NOT_BE_PERSISTED:
-        return memgraph::dbms::RegisterMainReplicaCoordinatorStatus::COULD_NOT_BE_PERSISTED;
-      case memgraph::coordination::RegisterMainReplicaCoordinatorStatus::SUCCESS:
-        break;
-    }
-
-  instance_client.GetValue()->StartFrequentCheck();
-  return {};
+auto CoordinatorHandler::UnregisterReplicationInstance(std::string instance_name)
+    -> coordination::UnregisterInstanceCoordinatorStatus {
+  return coordinator_state_.UnregisterReplicationInstance(std::move(instance_name));
 }
 
-auto CoordinatorHandler::ShowReplicasOnCoordinator() const -> std::vector<coordination::CoordinatorEntityInfo> {
-  return dbms_handler_.CoordinatorState().ShowReplicas();
+auto CoordinatorHandler::SetReplicationInstanceToMain(std::string instance_name)
+    -> coordination::SetInstanceToMainCoordinatorStatus {
+  return coordinator_state_.SetReplicationInstanceToMain(std::move(instance_name));
 }
 
-auto CoordinatorHandler::PingReplicasOnCoordinator() const -> std::unordered_map<std::string_view, bool> {
-  return dbms_handler_.CoordinatorState().PingReplicas();
+auto CoordinatorHandler::ShowInstances() const -> std::vector<coordination::InstanceStatus> {
+  return coordinator_state_.ShowInstances();
 }
 
-auto CoordinatorHandler::ShowMainOnCoordinator() const -> std::optional<coordination::CoordinatorEntityInfo> {
-  return dbms_handler_.CoordinatorState().ShowMain();
-}
-
-auto CoordinatorHandler::PingMainOnCoordinator() const -> std::optional<coordination::CoordinatorEntityHealthInfo> {
-  return dbms_handler_.CoordinatorState().PingMain();
-}
-
-auto CoordinatorHandler::DoFailover() const -> DoFailoverStatus {
-  auto status = dbms_handler_.CoordinatorState().DoFailover();
-  switch (status) {
-    case memgraph::coordination::DoFailoverStatus::ALL_REPLICAS_DOWN:
-      return memgraph::dbms::DoFailoverStatus::ALL_REPLICAS_DOWN;
-    case memgraph::coordination::DoFailoverStatus::SUCCESS:
-      return memgraph::dbms::DoFailoverStatus::SUCCESS;
-    case memgraph::coordination::DoFailoverStatus::MAIN_ALIVE:
-      return memgraph::dbms::DoFailoverStatus::MAIN_ALIVE;
-    case memgraph::coordination::DoFailoverStatus::CLUSTER_UNINITIALIZED:
-      return memgraph::dbms::DoFailoverStatus::CLUSTER_UNINITIALIZED;
-  }
+auto CoordinatorHandler::AddCoordinatorInstance(uint32_t raft_server_id, uint32_t raft_port, std::string raft_address)
+    -> void {
+  coordinator_state_.AddCoordinatorInstance(raft_server_id, raft_port, std::move(raft_address));
 }
 
 }  // namespace memgraph::dbms

src/dbms/coordinator_handler.hpp

@@ -13,54 +13,36 @@
 
 #ifdef MG_ENTERPRISE
 
-#include "utils/result.hpp"
+#include "coordination/coordinator_config.hpp"
+#include "coordination/coordinator_state.hpp"
+#include "coordination/instance_status.hpp"
+#include "coordination/register_main_replica_coordinator_status.hpp"
 
-#include <cstdint>
-#include <optional>
 #include <vector>
 
-namespace memgraph::coordination {
-struct CoordinatorEntityInfo;
-struct CoordinatorEntityHealthInfo;
-struct CoordinatorClientConfig;
-}  // namespace memgraph::coordination
-
 namespace memgraph::dbms {
 
-enum class RegisterMainReplicaCoordinatorStatus : uint8_t {
-  NAME_EXISTS,
-  END_POINT_EXISTS,
-  COULD_NOT_BE_PERSISTED,
-  NOT_COORDINATOR,
-  SUCCESS
-};
-
-enum class DoFailoverStatus : uint8_t { SUCCESS, ALL_REPLICAS_DOWN, MAIN_ALIVE, CLUSTER_UNINITIALIZED };
-
 class DbmsHandler;
 
 class CoordinatorHandler {
  public:
-  explicit CoordinatorHandler(DbmsHandler &dbms_handler);
+  explicit CoordinatorHandler(coordination::CoordinatorState &coordinator_state);
 
-  auto RegisterReplicaOnCoordinator(const memgraph::coordination::CoordinatorClientConfig &config)
-      -> utils::BasicResult<RegisterMainReplicaCoordinatorStatus>;
+  // TODO: (andi) When moving coordinator state on same instances, rename from RegisterReplicationInstance to
+  // RegisterInstance
+  auto RegisterReplicationInstance(coordination::CoordinatorClientConfig config)
+      -> coordination::RegisterInstanceCoordinatorStatus;
 
-  auto RegisterMainOnCoordinator(const memgraph::coordination::CoordinatorClientConfig &config)
-      -> utils::BasicResult<RegisterMainReplicaCoordinatorStatus>;
+  auto UnregisterReplicationInstance(std::string instance_name) -> coordination::UnregisterInstanceCoordinatorStatus;
 
-  auto ShowReplicasOnCoordinator() const -> std::vector<memgraph::coordination::CoordinatorEntityInfo>;
+  auto SetReplicationInstanceToMain(std::string instance_name) -> coordination::SetInstanceToMainCoordinatorStatus;
 
-  auto ShowMainOnCoordinator() const -> std::optional<memgraph::coordination::CoordinatorEntityInfo>;
+  auto ShowInstances() const -> std::vector<coordination::InstanceStatus>;
 
-  auto PingReplicasOnCoordinator() const -> std::unordered_map<std::string_view, bool>;
-
-  auto PingMainOnCoordinator() const -> std::optional<memgraph::coordination::CoordinatorEntityHealthInfo>;
-
-  auto DoFailover() const -> DoFailoverStatus;
+  auto AddCoordinatorInstance(uint32_t raft_server_id, uint32_t raft_port, std::string raft_address) -> void;
 
  private:
-  DbmsHandler &dbms_handler_;
+  coordination::CoordinatorState &coordinator_state_;
 };
 
 }  // namespace memgraph::dbms

src/dbms/coordinator_handlers.cpp

@@ -1,106 +0,0 @@
-// Copyright 2024 Memgraph Ltd.
-//
-// Use of this software is governed by the Business Source License
-// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
-// License, and you may not use this file except in compliance with the Business Source License.
-//
-// As of the Change Date specified in that file, in accordance with
-// the Business Source License, use of this software will be governed
-// by the Apache License, Version 2.0, included in the file
-// licenses/APL.txt.
-
-#ifdef MG_ENTERPRISE
-
-#include "dbms/coordinator_handlers.hpp"
-#include "dbms/utils.hpp"
-
-#include "coordination/coordinator_exceptions.hpp"
-#include "coordination/coordinator_rpc.hpp"
-#include "dbms/dbms_handler.hpp"
-#include "dbms/replication_client.hpp"
-
-namespace memgraph::dbms {
-
-void CoordinatorHandlers::Register(DbmsHandler &dbms_handler) {
-  auto &server = dbms_handler.CoordinatorState().GetCoordinatorServer();
-
-  server.Register<coordination::PromoteReplicaToMainRpc>(
-      [&dbms_handler](slk::Reader *req_reader, slk::Builder *res_builder) -> void {
-        spdlog::info("Received PromoteReplicaToMainRpc from coordinator server");
-        CoordinatorHandlers::PromoteReplicaToMainHandler(dbms_handler, req_reader, res_builder);
-      });
-}
-
-void CoordinatorHandlers::PromoteReplicaToMainHandler(DbmsHandler &dbms_handler, slk::Reader *req_reader,
-                                                      slk::Builder *res_builder) {
-  auto &repl_state = dbms_handler.ReplicationState();
-
-  if (!repl_state.IsReplica()) {
-    spdlog::error("Failover must be performed on replica!");
-    slk::Save(coordination::PromoteReplicaToMainRes{false}, res_builder);
-    return;
-  }
-
-  if (bool success = memgraph::dbms::DoReplicaToMainPromotion(dbms_handler); !success) {
-    spdlog::error("Promoting replica to main failed!");
-    slk::Save(coordination::PromoteReplicaToMainRes{false}, res_builder);
-    return;
-  }
-
-  coordination::PromoteReplicaToMainReq req;
-  slk::Load(&req, req_reader);
-
-  std::vector<replication::ReplicationClientConfig> clients_config;
-  clients_config.reserve(req.replication_clients_info.size());
-  std::ranges::transform(req.replication_clients_info, std::back_inserter(clients_config),
-                         [](const auto &repl_info_config) {
-                           return replication::ReplicationClientConfig{
-                               .name = repl_info_config.instance_name,
-                               .mode = repl_info_config.replication_mode,
-                               .ip_address = repl_info_config.replication_ip_address,
-                               .port = repl_info_config.replication_port,
-                           };
-                         });
-
-  std::ranges::for_each(clients_config, [&dbms_handler, &repl_state, &res_builder](const auto &config) {
-    auto instance_client = repl_state.RegisterReplica(config);
-    if (instance_client.HasError()) {
-      switch (instance_client.GetError()) {
-        case memgraph::replication::RegisterReplicaError::NOT_MAIN:
-          spdlog::error("Failover must be performed to main!");
-          slk::Save(coordination::PromoteReplicaToMainRes{false}, res_builder);
-          return;
-        case memgraph::replication::RegisterReplicaError::NAME_EXISTS:
-          spdlog::error("Replica with the same name already exists!");
-          slk::Save(coordination::PromoteReplicaToMainRes{false}, res_builder);
-          return;
-        case memgraph::replication::RegisterReplicaError::END_POINT_EXISTS:
-          spdlog::error("Replica with the same endpoint already exists!");
-          slk::Save(coordination::PromoteReplicaToMainRes{false}, res_builder);
-          return;
-        case memgraph::replication::RegisterReplicaError::COULD_NOT_BE_PERSISTED:
-          spdlog::error("Registered replica could not be persisted!");
-          slk::Save(coordination::PromoteReplicaToMainRes{false}, res_builder);
-          return;
-        case memgraph::replication::RegisterReplicaError::SUCCESS:
-          break;
-      }
-    }
-
-    auto &instance_client_ref = *instance_client.GetValue();
-    const bool all_clients_good = memgraph::dbms::RegisterAllDatabasesClients(dbms_handler, instance_client_ref);
-
-    if (!all_clients_good) {
-      spdlog::error("Failed to register all databases to the REPLICA \"{}\"", config.name);
-      slk::Save(coordination::PromoteReplicaToMainRes{false}, res_builder);
-      return;
-    }
-
-    StartReplicaClient(dbms_handler, instance_client_ref);
-  });
-
-  slk::Save(coordination::PromoteReplicaToMainRes{true}, res_builder);
-}
-
-}  // namespace memgraph::dbms
-#endif

src/dbms/database.cpp

@@ -1,4 +1,4 @@
-// Copyright 2023 Memgraph Ltd.
+// Copyright 2024 Memgraph Ltd.
 //
 // Use of this software is governed by the Business Source License
 // included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
@@ -11,10 +11,7 @@
 
 #include "dbms/database.hpp"
 #include "dbms/inmemory/storage_helper.hpp"
-#include "dbms/replication_handler.hpp"
-#include "flags/storage_mode.hpp"
 #include "storage/v2/disk/storage.hpp"
-#include "storage/v2/inmemory/storage.hpp"
 #include "storage/v2/storage_mode.hpp"
 
 template struct memgraph::utils::Gatekeeper<memgraph::dbms::Database>;

src/dbms/database.hpp

@@ -110,7 +110,7 @@ class Database {
    * @param force_directory Use the configured directory, do not try to decipher the multi-db version
    * @return DatabaseInfo
    */
-  DatabaseInfo GetInfo(bool force_directory, replication::ReplicationRole replication_role) const {
+  DatabaseInfo GetInfo(bool force_directory, replication_coordination_glue::ReplicationRole replication_role) const {
     DatabaseInfo info;
     info.storage_info = storage_->GetInfo(force_directory, replication_role);
     info.triggers = trigger_store_.GetTriggerInfo().size();

src/dbms/dbms_handler.cpp

@@ -11,29 +11,76 @@
 
 #include "dbms/dbms_handler.hpp"
 
-#include "dbms/coordinator_handlers.hpp"
-#include "flags/replication.hpp"
-
 #include <cstdint>
 #include <filesystem>
 
 #include "dbms/constants.hpp"
 #include "dbms/global.hpp"
-#include "dbms/replication_client.hpp"
+#include "flags/experimental.hpp"
 #include "spdlog/spdlog.h"
+#include "system/include/system/system.hpp"
 #include "utils/exceptions.hpp"
 #include "utils/logging.hpp"
 #include "utils/uuid.hpp"
 
 namespace memgraph::dbms {
 
-#ifdef MG_ENTERPRISE
-
 namespace {
-constexpr std::string_view kDBPrefix = "database:";                               // Key prefix for database durability
-constexpr std::string_view kLastCommitedSystemTsKey = "last_commited_system_ts";  // Key for timestamp durability
+constexpr std::string_view kDBPrefix = "database:";  // Key prefix for database durability
+
+std::string RegisterReplicaErrorToString(query::RegisterReplicaError error) {
+  switch (error) {
+    using enum query::RegisterReplicaError;
+    case NAME_EXISTS:
+      return "NAME_EXISTS";
+    case ENDPOINT_EXISTS:
+      return "ENDPOINT_EXISTS";
+    case CONNECTION_FAILED:
+      return "CONNECTION_FAILED";
+    case COULD_NOT_BE_PERSISTED:
+      return "COULD_NOT_BE_PERSISTED";
+    case ERROR_ACCEPTING_MAIN:
+      return "ERROR_ACCEPTING_MAIN";
+  }
+}
+
+// Per storage
+// NOTE Storage will connect to all replicas. Future work might change this
+void RestoreReplication(replication::RoleMainData &mainData, DatabaseAccess db_acc) {
+  spdlog::info("Restoring replication role.");
+
+  // Each individual client has already been restored and started. Here we just go through each database and start its
+  // client
+  for (auto &instance_client : mainData.registered_replicas_) {
+    spdlog::info("Replica {} restoration started for {}.", instance_client.name_, db_acc->name());
+    const auto &ret = db_acc->storage()->repl_storage_state_.replication_clients_.WithLock(
+        [&, db_acc](auto &storage_clients) mutable -> utils::BasicResult<query::RegisterReplicaError> {
+          auto client = std::make_unique<storage::ReplicationStorageClient>(instance_client, mainData.uuid_);
+          auto *storage = db_acc->storage();
+          client->Start(storage, std::move(db_acc));
+          // After start the storage <-> replica state should be READY or RECOVERING (if correctly started)
+          // MAYBE_BEHIND isn't a statement of the current state, this is the default value
+          // Failed to start due to branching of MAIN and REPLICA
+          if (client->State() == storage::replication::ReplicaState::MAYBE_BEHIND) {
+            spdlog::warn("Connection failed when registering replica {}. Replica will still be registered.",
+                         instance_client.name_);
+          }
+          storage_clients.push_back(std::move(client));
+          return {};
+        });
+
+    if (ret.HasError()) {
+      MG_ASSERT(query::RegisterReplicaError::CONNECTION_FAILED != ret.GetError());
+      LOG_FATAL("Failure when restoring replica {}: {}.", instance_client.name_,
+                RegisterReplicaErrorToString(ret.GetError()));
+    }
+    spdlog::info("Replica {} restored for {}.", instance_client.name_, db_acc->name());
+  }
+  spdlog::info("Replication role restored to MAIN.");
+}
 }  // namespace
 
+#ifdef MG_ENTERPRISE
 struct Durability {
   enum class DurabilityVersion : uint8_t {
     V0 = 0,
@@ -112,11 +159,9 @@ struct Durability {
   }
 };
 
-DbmsHandler::DbmsHandler(
-    storage::Config config,
-    memgraph::utils::Synchronized<memgraph::auth::Auth, memgraph::utils::WritePrioritizedRWLock> *auth,
-    bool recovery_on_startup)
-    : default_config_{std::move(config)}, repl_state_{ReplicationStateRootPath(default_config_)} {
+DbmsHandler::DbmsHandler(storage::Config config, replication::ReplicationState &repl_state, auth::SynchedAuth &auth,
+                         bool recovery_on_startup)
+    : default_config_{std::move(config)}, auth_{auth}, repl_state_{repl_state} {
   // TODO: Decouple storage config from dbms config
   // TODO: Save individual db configs inside the kvstore and restore from there
 
@@ -150,19 +195,13 @@ DbmsHandler::DbmsHandler(
       const auto uuid = json.at("uuid").get<utils::UUID>();
       const auto rel_dir = json.at("rel_dir").get<std::filesystem::path>();
       spdlog::info("Restoring database {} at {}.", name, rel_dir);
-      auto new_db = New_(name, uuid, rel_dir);
+      auto new_db = New_(name, uuid, nullptr, rel_dir);
       MG_ASSERT(!new_db.HasError(), "Failed while creating database {}.", name);
       directories.emplace(rel_dir.filename());
       spdlog::info("Database {} restored.", name);
     }
-    // Read the last timestamp
-    auto lcst = durability_->Get(kLastCommitedSystemTsKey);
-    if (lcst) {
-      last_commited_system_timestamp_ = std::stoul(*lcst);
-      system_timestamp_ = last_commited_system_timestamp_;
-    }
   } else {  // Clear databases from the durability list and auth
-    auto locked_auth = auth->Lock();
+    auto locked_auth = auth_.Lock();
     auto it = durability_->begin(std::string{kDBPrefix});
     auto end = durability_->end(std::string{kDBPrefix});
     for (; it != end; ++it) {
@@ -172,8 +211,6 @@ DbmsHandler::DbmsHandler(
       locked_auth->DeleteDatabase(name);
       durability_->Delete(key);
     }
-    // Delete the last timestamp
-    durability_->Delete(kLastCommitedSystemTsKey);
   }
 
   /*
@@ -198,45 +235,31 @@ DbmsHandler::DbmsHandler(
    */
   // Setup the default DB
   SetupDefault_();
-
-  /*
-   * REPLICATION RECOVERY AND STARTUP
-   */
-  // Startup replication state (if recovered at startup)
-  auto replica = [this](replication::RoleReplicaData const &data) { return StartRpcServer(*this, data); };
-  // Replication recovery and frequent check start
-  auto main = [this](replication::RoleMainData &data) {
-    for (auto &client : data.registered_replicas_) {
-      SystemRestore(client);
-    }
-    ForEach([this](DatabaseAccess db) { RecoverReplication(db); });
-    for (auto &client : data.registered_replicas_) {
-      StartReplicaClient(*this, client);
-    }
-    return true;
-  };
-  // Startup proccess for main/replica
-  MG_ASSERT(std::visit(memgraph::utils::Overloaded{replica, main}, repl_state_.ReplicationData()),
-            "Replica recovery failure!");
-
-  // Warning
-  if (default_config_.durability.snapshot_wal_mode == storage::Config::Durability::SnapshotWalMode::DISABLED &&
-      repl_state_.IsMain()) {
-    spdlog::warn(
-        "The instance has the MAIN replication role, but durability logs and snapshots are disabled. Please "
-        "consider "
-        "enabling durability by using --storage-snapshot-interval-sec and --storage-wal-enabled flags because "
-        "without write-ahead logs this instance is not replicating any data.");
-  }
-
-  // MAIN or REPLICA instance
-  if (FLAGS_coordinator_server_port) {
-    CoordinatorHandlers::Register(*this);
-    MG_ASSERT(coordinator_state_.GetCoordinatorServer().Start(), "Failed to start coordinator server!");
-  }
 }
 
-DbmsHandler::DeleteResult DbmsHandler::TryDelete(std::string_view db_name) {
+struct DropDatabase : memgraph::system::ISystemAction {
+  explicit DropDatabase(utils::UUID uuid) : uuid_{uuid} {}
+  void DoDurability() override { /* Done during DBMS execution */
+  }
+
+  bool DoReplication(replication::ReplicationClient &client, const utils::UUID &main_uuid,
+                     replication::ReplicationEpoch const &epoch,
+                     memgraph::system::Transaction const &txn) const override {
+    auto check_response = [](const storage::replication::DropDatabaseRes &response) {
+      return response.result != storage::replication::DropDatabaseRes::Result::FAILURE;
+    };
+
+    return client.SteamAndFinalizeDelta<storage::replication::DropDatabaseRpc>(
+        check_response, main_uuid, std::string(epoch.id()), txn.last_committed_system_timestamp(), txn.timestamp(),
+        uuid_);
+  }
+  void PostReplication(replication::RoleMainData &mainData) const override {}
+
+ private:
+  utils::UUID uuid_;
+};
+
+DbmsHandler::DeleteResult DbmsHandler::TryDelete(std::string_view db_name, system::Transaction *transaction) {
   std::lock_guard<LockT> wr(lock_);
   if (db_name == kDefaultDB) {
     // MSG cannot delete the default db
@@ -273,9 +296,10 @@ DbmsHandler::DeleteResult DbmsHandler::TryDelete(std::string_view db_name) {
 
   // Success
   // Save delta
-  if (system_transaction_) {
-    system_transaction_->delta.emplace(SystemTransaction::Delta::drop_database, uuid);
+  if (transaction) {
+    transaction->AddAction<DropDatabase>(uuid);
   }
+
   return {};
 }
 
@@ -296,18 +320,50 @@ DbmsHandler::DeleteResult DbmsHandler::Delete(utils::UUID uuid) {
   return Delete_(db_name);
 }
 
-DbmsHandler::NewResultT DbmsHandler::New_(storage::Config storage_config) {
+struct CreateDatabase : memgraph::system::ISystemAction {
+  explicit CreateDatabase(storage::SalientConfig config, DatabaseAccess db_acc)
+      : config_{std::move(config)}, db_acc(db_acc) {}
+
+  void DoDurability() override {
+    // Done during dbms execution
+  }
+
+  bool DoReplication(replication::ReplicationClient &client, const utils::UUID &main_uuid,
+                     replication::ReplicationEpoch const &epoch,
+                     memgraph::system::Transaction const &txn) const override {
+    auto check_response = [](const storage::replication::CreateDatabaseRes &response) {
+      return response.result != storage::replication::CreateDatabaseRes::Result::FAILURE;
+    };
+
+    return client.SteamAndFinalizeDelta<storage::replication::CreateDatabaseRpc>(
+        check_response, main_uuid, std::string(epoch.id()), txn.last_committed_system_timestamp(), txn.timestamp(),
+        config_);
+  }
+
+  void PostReplication(replication::RoleMainData &mainData) const override {
+    // Sync database with REPLICAs
+    // NOTE: The function bellow is used to create ReplicationStorageClient, so it must be called on a new storage
+    // We don't need to have it here, since the function won't fail even if the replication client fails to
+    // connect We will just have everything ready, for recovery at some point.
+    dbms::DbmsHandler::RecoverStorageReplication(db_acc, mainData);
+  }
+
+ private:
+  storage::SalientConfig config_;
+  DatabaseAccess db_acc;
+};
+
+DbmsHandler::NewResultT DbmsHandler::New_(storage::Config storage_config, system::Transaction *txn) {
   auto new_db = db_handler_.New(storage_config, repl_state_);
 
   if (new_db.HasValue()) {  // Success
                             // Save delta
-    if (system_transaction_) {
-      system_transaction_->delta.emplace(SystemTransaction::Delta::create_database, storage_config.salient);
-    }
     UpdateDurability(storage_config);
-    return new_db.GetValue();
+    if (txn) {
+      txn->AddAction<CreateDatabase>(storage_config.salient, new_db.GetValue());
+    }
   }
-  return new_db.GetError();
+  return new_db;
 }
 
 DbmsHandler::DeleteResult DbmsHandler::Delete_(std::string_view db_name) {
@@ -361,89 +417,19 @@ void DbmsHandler::UpdateDurability(const storage::Config &config, std::optional<
   durability_->Put(key, val);
 }
 
-AllSyncReplicaStatus DbmsHandler::Commit() {
-  if (system_transaction_ == std::nullopt || system_transaction_->delta == std::nullopt)
-    return AllSyncReplicaStatus::AllCommitsConfirmed;  // Nothing to commit
-  const auto &delta = *system_transaction_->delta;
-
-  auto sync_status = AllSyncReplicaStatus::AllCommitsConfirmed;
-  // TODO Create a system client that can handle all of this automatically
-  switch (delta.action) {
-    using enum SystemTransaction::Delta::Action;
-    case CREATE_DATABASE: {
-      // Replication
-      auto main_handler = [&](memgraph::replication::RoleMainData &main_data) {
-        // TODO: data race issue? registered_replicas_ access not protected
-        // This is sync in any case, as this is the startup
-        for (auto &client : main_data.registered_replicas_) {
-          bool completed = SteamAndFinalizeDelta<storage::replication::CreateDatabaseRpc>(
-              client,
-              [](const storage::replication::CreateDatabaseRes &response) {
-                return response.result != storage::replication::CreateDatabaseRes::Result::FAILURE;
-              },
-              std::string(main_data.epoch_.id()), last_commited_system_timestamp_,
-              system_transaction_->system_timestamp, delta.config);
-          // TODO: reduce duplicate code
-          if (!completed && client.mode_ == replication_coordination_glue::ReplicationMode::SYNC) {
-            sync_status = AllSyncReplicaStatus::SomeCommitsUnconfirmed;
-          }
-        }
-        // Sync database with REPLICAs
-        RecoverReplication(Get_(delta.config.name));
-      };
-      auto replica_handler = [](memgraph::replication::RoleReplicaData &) { /* Nothing to do */ };
-      std::visit(utils::Overloaded{main_handler, replica_handler}, repl_state_.ReplicationData());
-    } break;
-    case DROP_DATABASE: {
-      // Replication
-      auto main_handler = [&](memgraph::replication::RoleMainData &main_data) {
-        // TODO: data race issue? registered_replicas_ access not protected
-        // This is sync in any case, as this is the startup
-        for (auto &client : main_data.registered_replicas_) {
-          bool completed = SteamAndFinalizeDelta<storage::replication::DropDatabaseRpc>(
-              client,
-              [](const storage::replication::DropDatabaseRes &response) {
-                return response.result != storage::replication::DropDatabaseRes::Result::FAILURE;
-              },
-              std::string(main_data.epoch_.id()), last_commited_system_timestamp_,
-              system_transaction_->system_timestamp, delta.uuid);
-          // TODO: reduce duplicate code
-          if (!completed && client.mode_ == replication_coordination_glue::ReplicationMode::SYNC) {
-            sync_status = AllSyncReplicaStatus::SomeCommitsUnconfirmed;
-          }
-        }
-      };
-      auto replica_handler = [](memgraph::replication::RoleReplicaData &) { /* Nothing to do */ };
-      std::visit(utils::Overloaded{main_handler, replica_handler}, repl_state_.ReplicationData());
-    } break;
-  }
-
-  durability_->Put(kLastCommitedSystemTsKey, std::to_string(system_transaction_->system_timestamp));
-  last_commited_system_timestamp_ = system_transaction_->system_timestamp;
-  ResetSystemTransaction();
-  return sync_status;
-}
-
-#else  // not MG_ENTERPRISE
-
-AllSyncReplicaStatus DbmsHandler::Commit() {
-  if (system_transaction_ == std::nullopt || system_transaction_->delta == std::nullopt) {
-    return AllSyncReplicaStatus::AllCommitsConfirmed;  // Nothing to commit
-  }
-  const auto &delta = *system_transaction_->delta;
-
-  switch (delta.action) {
-    using enum SystemTransaction::Delta::Action;
-    case CREATE_DATABASE:
-    case DROP_DATABASE:
-      /* Community edition doesn't support multi-tenant replication */
-      break;
-  }
-
-  last_commited_system_timestamp_ = system_transaction_->system_timestamp;
-  ResetSystemTransaction();
-  return AllSyncReplicaStatus::AllCommitsConfirmed;
-}
-
 #endif
+
+void DbmsHandler::RecoverStorageReplication(DatabaseAccess db_acc, replication::RoleMainData &role_main_data) {
+  using enum memgraph::flags::Experiments;
+  auto const is_enterprise = license::global_license_checker.IsEnterpriseValidFast();
+  auto experimental_system_replication = flags::AreExperimentsEnabled(SYSTEM_REPLICATION);
+  if ((is_enterprise && experimental_system_replication) || db_acc->name() == dbms::kDefaultDB) {
+    // Handle global replication state
+    spdlog::info("Replication configuration will be stored and will be automatically restored in case of a crash.");
+    // RECOVER REPLICA CONNECTIONS
+    memgraph::dbms::RestoreReplication(role_main_data, db_acc);
+  } else if (!role_main_data.registered_replicas_.empty()) {
+    spdlog::warn("Multi-tenant replication is currently not supported!");
+  }
+}
 }  // namespace memgraph::dbms

src/dbms/dbms_handler.hpp

@@ -25,24 +25,25 @@
 #include "constants.hpp"
 #include "dbms/database.hpp"
 #include "dbms/inmemory/replication_handlers.hpp"
-#include "dbms/replication_handler.hpp"
+#include "dbms/rpc.hpp"
 #include "kvstore/kvstore.hpp"
+#include "license/license.hpp"
 #include "replication/replication_client.hpp"
+#include "replication_coordination_glue/handler.hpp"
 #include "storage/v2/config.hpp"
-#include "storage/v2/replication/enums.hpp"
-#include "storage/v2/replication/rpc.hpp"
 #include "storage/v2/transaction.hpp"
+#include "system/system.hpp"
 #include "utils/thread_pool.hpp"
 #ifdef MG_ENTERPRISE
 #include "coordination/coordinator_state.hpp"
 #include "dbms/database_handler.hpp"
 #endif
-#include "dbms/transaction.hpp"
 #include "global.hpp"
 #include "query/config.hpp"
 #include "query/interpreter_context.hpp"
 #include "spdlog/spdlog.h"
 #include "storage/v2/isolation_level.hpp"
+#include "system/system.hpp"
 #include "utils/logging.hpp"
 #include "utils/result.hpp"
 #include "utils/rw_lock.hpp"
@@ -51,11 +52,6 @@
 
 namespace memgraph::dbms {
 
-enum class AllSyncReplicaStatus {
-  AllCommitsConfirmed,
-  SomeCommitsUnconfirmed,
-};
-
 struct Statistics {
   uint64_t num_vertex;           //!< Sum of vertexes in every database
   uint64_t num_edges;            //!< Sum of edges in every database
@@ -111,8 +107,7 @@ class DbmsHandler {
    * @param auth pointer to the global authenticator
    * @param recovery_on_startup restore databases (and its content) and authentication data
    */
-  DbmsHandler(storage::Config config,
-              memgraph::utils::Synchronized<memgraph::auth::Auth, memgraph::utils::WritePrioritizedRWLock> *auth,
+  DbmsHandler(storage::Config config, replication::ReplicationState &repl_state, auth::SynchedAuth &auth,
               bool recovery_on_startup);  // TODO If more arguments are added use a config struct
 #else
   /**
@@ -120,15 +115,13 @@ class DbmsHandler {
    *
    * @param configs storage configuration
    */
-  DbmsHandler(storage::Config config)
-      : repl_state_{ReplicationStateRootPath(config)},
+  DbmsHandler(storage::Config config, replication::ReplicationState &repl_state)
+      : repl_state_{repl_state},
         db_gatekeeper_{[&] {
                          config.salient.name = kDefaultDB;
                          return std::move(config);
                        }(),
-                       repl_state_} {
-    RecoverReplication(Get());
-  }
+                       repl_state_} {}
 #endif
 
 #ifdef MG_ENTERPRISE
@@ -138,10 +131,10 @@ class DbmsHandler {
    * @param name name of the database
    * @return NewResultT context on success, error on failure
    */
-  NewResultT New(const std::string &name) {
+  NewResultT New(const std::string &name, system::Transaction *txn = nullptr) {
     std::lock_guard<LockT> wr(lock_);
     const auto uuid = utils::UUID{};
-    return New_(name, uuid);
+    return New_(name, uuid, txn);
   }
 
   /**
@@ -234,7 +227,7 @@ class DbmsHandler {
    * @param db_name database name
    * @return DeleteResult error on failure
    */
-  DeleteResult TryDelete(std::string_view db_name);
+  DeleteResult TryDelete(std::string_view db_name, system::Transaction *transaction = nullptr);
 
   /**
    * @brief Delete or defer deletion of database.
@@ -274,16 +267,29 @@ class DbmsHandler {
   bool IsReplica() const { return repl_state_.IsReplica(); }
 
 #ifdef MG_ENTERPRISE
-  coordination::CoordinatorState &CoordinatorState() { return coordinator_state_; }
+  // coordination::CoordinatorState &CoordinatorState() { return coordinator_state_; }
 #endif
 
+  /**
+   * @brief Return all active databases.
+   *
+   * @return std::vector<std::string>
+   */
+  auto Count() const -> std::size_t {
+#ifdef MG_ENTERPRISE
+    std::shared_lock<LockT> rd(lock_);
+    return db_handler_.size();
+#else
+    return 1;
+#endif
+  }
+
   /**
    * @brief Return the statistics all databases.
    *
    * @return Statistics
    */
-  Statistics Stats() {
-    auto const replication_role = repl_state_.GetRole();
+  Statistics Stats(memgraph::replication_coordination_glue::ReplicationRole replication_role) {
     Statistics stats{};
     // TODO: Handle overflow?
 #ifdef MG_ENTERPRISE
@@ -319,8 +325,7 @@ class DbmsHandler {
    *
    * @return std::vector<DatabaseInfo>
    */
-  std::vector<DatabaseInfo> Info() {
-    auto const replication_role = repl_state_.GetRole();
+  std::vector<DatabaseInfo> Info(memgraph::replication_coordination_glue::ReplicationRole replication_role) {
     std::vector<DatabaseInfo> res;
 #ifdef MG_ENTERPRISE
     std::shared_lock<LockT> rd(lock_);
@@ -407,98 +412,17 @@ class DbmsHandler {
     }
   }
 
-  void NewSystemTransaction() {
-    DMG_ASSERT(!system_transaction_, "Already running a system transaction");
-    system_transaction_.emplace(++system_timestamp_);
-  }
-
-  void ResetSystemTransaction() { system_transaction_.reset(); }
-
-  //! \tparam RPC An rpc::RequestResponse
-  //! \tparam Args the args type
-  //! \param client the client to use for rpc communication
-  //! \param check predicate to check response is ok
-  //! \param args arguments to forward to the rpc request
-  //! \return If replica stream is completed or enqueued
-  template <typename RPC, typename... Args>
-  bool SteamAndFinalizeDelta(auto &client, auto &&check, Args &&...args) {
-    try {
-      auto stream = client.rpc_client_.template Stream<RPC>(std::forward<Args>(args)...);
-      auto task = [&client, check = std::forward<decltype(check)>(check), stream = std::move(stream)]() mutable {
-        if (stream.IsDefunct()) {
-          client.state_.WithLock([](auto &state) { state = memgraph::replication::ReplicationClient::State::BEHIND; });
-          return false;
-        }
-        try {
-          if (check(stream.AwaitResponse())) {
-            return true;
-          }
-        } catch (memgraph::rpc::GenericRpcFailedException const &e) {
-          // swallow error, fallthrough to error handling
-        }
-        // This replica needs SYSTEM recovery
-        client.state_.WithLock([](auto &state) { state = memgraph::replication::ReplicationClient::State::BEHIND; });
-        return false;
-      };
-
-      if (client.mode_ == memgraph::replication_coordination_glue::ReplicationMode::ASYNC) {
-        client.thread_pool_.AddTask([task = utils::CopyMovableFunctionWrapper{std::move(task)}]() mutable { task(); });
-        return true;
-      }
-
-      return task();
-    } catch (memgraph::rpc::GenericRpcFailedException const &e) {
-      // This replica needs SYSTEM recovery
-      client.state_.WithLock([](auto &state) { state = memgraph::replication::ReplicationClient::State::BEHIND; });
-      return false;
-    }
-  };
-
-  AllSyncReplicaStatus Commit();
-
-  auto LastCommitedTS() const -> uint64_t { return last_commited_system_timestamp_; }
-  void SetLastCommitedTS(uint64_t new_ts) { last_commited_system_timestamp_.store(new_ts); }
+  static void RecoverStorageReplication(DatabaseAccess db_acc, replication::RoleMainData &role_main_data);
 
+  auto default_config() const -> storage::Config const & {
 #ifdef MG_ENTERPRISE
-  // When being called by intepreter no need to gain lock, it should already be under a system transaction
-  // But concurrently the FrequentCheck is running and will need to lock before reading last_commited_system_timestamp_
-  template <bool REQUIRE_LOCK = false>
-  void SystemRestore(replication::ReplicationClient &client) {
-    // Check if system is up to date
-    if (client.state_.WithLock(
-            [](auto &state) { return state == memgraph::replication::ReplicationClient::State::READY; }))
-      return;
-
-    // Try to recover...
-    {
-      auto [database_configs, last_commited_system_timestamp] = std::invoke([&] {
-        auto sys_guard =
-            std::unique_lock{system_lock_, std::defer_lock};  // ensure no other system transaction in progress
-        if constexpr (REQUIRE_LOCK) {
-          sys_guard.lock();
-        }
-        auto configs = std::vector<storage::SalientConfig>{};
-        ForEach([&configs](DatabaseAccess acc) { configs.emplace_back(acc->config().salient); });
-        return std::pair{configs, last_commited_system_timestamp_.load()};
-      });
-      try {
-        auto stream = client.rpc_client_.Stream<storage::replication::SystemRecoveryRpc>(last_commited_system_timestamp,
-                                                                                         std::move(database_configs));
-        const auto response = stream.AwaitResponse();
-        if (response.result == storage::replication::SystemRecoveryRes::Result::FAILURE) {
-          client.state_.WithLock([](auto &state) { state = memgraph::replication::ReplicationClient::State::BEHIND; });
-          return;
-        }
-      } catch (memgraph::rpc::GenericRpcFailedException const &e) {
-        client.state_.WithLock([](auto &state) { state = memgraph::replication::ReplicationClient::State::BEHIND; });
-        return;
-      }
-    }
-
-    // Successfully recovered
-    client.state_.WithLock([](auto &state) { state = memgraph::replication::ReplicationClient::State::READY; });
-  }
+    return default_config_;
+#else
+    const auto acc = db_gatekeeper_.access();
+    MG_ASSERT(acc, "Failed to get default database!");
+    return acc->get()->config();
 #endif
+  }
 
  private:
 #ifdef MG_ENTERPRISE
@@ -524,7 +448,8 @@ class DbmsHandler {
    * @param uuid undelying RocksDB directory
    * @return NewResultT context on success, error on failure
    */
-  NewResultT New_(std::string_view name, utils::UUID uuid, std::optional<std::filesystem::path> rel_dir = {}) {
+  NewResultT New_(std::string_view name, utils::UUID uuid, system::Transaction *txn = nullptr,
+                  std::optional<std::filesystem::path> rel_dir = {}) {
     auto config_copy = default_config_;
     config_copy.salient.name = name;
     config_copy.salient.uuid = uuid;
@@ -535,7 +460,7 @@ class DbmsHandler {
       storage::UpdatePaths(config_copy,
                            default_config_.durability.storage_directory / kMultiTenantDir / std::string{uuid});
     }
-    return New_(std::move(config_copy));
+    return New_(std::move(config_copy), txn);
   }
 
   /**
@@ -544,11 +469,11 @@ class DbmsHandler {
    * @param config configuration to be used
    * @return NewResultT context on success, error on failure
    */
-  NewResultT New_(const storage::SalientConfig &config) {
+  NewResultT New_(const storage::SalientConfig &config, system::Transaction *txn = nullptr) {
     auto config_copy = default_config_;
     config_copy.salient = config;  // name, uuid, mode, etc
     UpdatePaths(config_copy, config_copy.durability.storage_directory / kMultiTenantDir / std::string{config.uuid});
-    return New_(std::move(config_copy));
+    return New_(std::move(config_copy), txn);
   }
 
   /**
@@ -557,7 +482,7 @@ class DbmsHandler {
    * @param storage_config storage configuration
    * @return NewResultT context on success, error on failure
    */
-  NewResultT New_(storage::Config storage_config);
+  DbmsHandler::NewResultT New_(storage::Config storage_config, system::Transaction *txn = nullptr);
 
   // TODO: new overload of Delete_ with DatabaseAccess
   DeleteResult Delete_(std::string_view db_name);
@@ -572,7 +497,8 @@ class DbmsHandler {
       Get(kDefaultDB);
     } catch (const UnknownDatabaseException &) {
       // No default DB restored, create it
-      MG_ASSERT(New_(kDefaultDB, {/* random UUID */}, ".").HasValue(), "Failed while creating the default database");
+      MG_ASSERT(New_(kDefaultDB, {/* random UUID */}, nullptr, ".").HasValue(),
+                "Failed while creating the default database");
     }
 
     // For back-compatibility...
@@ -659,35 +585,21 @@ class DbmsHandler {
   }
 #endif
 
-  void RecoverReplication(DatabaseAccess db_acc) {
-    if (allow_mt_repl || db_acc->name() == dbms::kDefaultDB) {
-      // Handle global replication state
-      spdlog::info("Replication configuration will be stored and will be automatically restored in case of a crash.");
-      // RECOVER REPLICA CONNECTIONS
-      memgraph::dbms::RestoreReplication(repl_state_, std::move(db_acc));
-    } else if (const ::memgraph::replication::RoleMainData *data =
-                   std::get_if<::memgraph::replication::RoleMainData>(&repl_state_.ReplicationData());
-               data && !data->registered_replicas_.empty()) {
-      spdlog::warn("Multi-tenant replication is currently not supported!");
-    }
-  }
-
 #ifdef MG_ENTERPRISE
   mutable LockT lock_{utils::RWLock::Priority::READ};  //!< protective lock
   storage::Config default_config_;                     //!< Storage configuration used when creating new databases
   DatabaseHandler db_handler_;                         //!< multi-tenancy storage handler
-  std::unique_ptr<kvstore::KVStore> durability_;       //!< list of active dbs (pointer so we can postpone its creation)
-  coordination::CoordinatorState coordinator_state_;  //!< Replication coordinator
+  // TODO: move to be common
+  std::unique_ptr<kvstore::KVStore> durability_;  //!< list of active dbs (pointer so we can postpone its creation)
+  auth::SynchedAuth &auth_;                       //!< Synchronized auth::Auth
 #endif
-  // TODO: Make an api
- public:
-  utils::ResourceLock system_lock_{};  //!> Ensure exclusive access for system queries
  private:
-  std::optional<SystemTransaction> system_transaction_;      //!< Current system transaction (only one at a time)
-  uint64_t system_timestamp_{storage::kTimestampInitialId};  //!< System timestamp
-  std::atomic_uint64_t last_commited_system_timestamp_{
-      storage::kTimestampInitialId};          //!< Last commited system timestamp
-  replication::ReplicationState repl_state_;  //!< Global replication state
+  // NOTE: atm the only reason this exists here, is because we pass it into the construction of New Database's
+  //       Database only uses it as a convience to make the correct Access without out needing to be told the
+  //       current replication role. TODO: make Database Access explicit about the role and remove this from
+  //       dbms stuff
+  replication::ReplicationState &repl_state_;  //!< Ref to global replication state
+
 #ifndef MG_ENTERPRISE
   mutable utils::Gatekeeper<Database> db_gatekeeper_;  //!< Single databases gatekeeper
 #endif

src/dbms/handler.hpp

@@ -144,6 +144,8 @@ class Handler {
   auto cbegin() const { return items_.cbegin(); }
   auto cend() const { return items_.cend(); }
 
+  auto size() const { return items_.size(); }
+
   struct string_hash {
     using is_transparent = void;
     [[nodiscard]] size_t operator()(const char *s) const { return std::hash<std::string_view>{}(s); }

src/dbms/inmemory/replication_handlers.cpp

@@ -23,7 +23,7 @@
 #include "storage/v2/inmemory/storage.hpp"
 #include "storage/v2/inmemory/unique_constraints.hpp"
 
-using memgraph::replication::ReplicationRole;
+using memgraph::replication_coordination_glue::ReplicationRole;
 using memgraph::storage::Delta;
 using memgraph::storage::EdgeAccessor;
 using memgraph::storage::EdgeRef;
@@ -76,58 +76,110 @@ std::optional<DatabaseAccess> GetDatabaseAccessor(dbms::DbmsHandler *dbms_handle
     return std::nullopt;
   }
 }
+
+void LogWrongMain(const std::optional<utils::UUID> &current_main_uuid, const utils::UUID &main_req_id,
+                  std::string_view rpc_req) {
+  spdlog::error("Received {} with main_id: {} != current_main_uuid: {}", rpc_req, std::string(main_req_id),
+                current_main_uuid.has_value() ? std::string(current_main_uuid.value()) : "");
+}
 }  // namespace
 
-void InMemoryReplicationHandlers::Register(dbms::DbmsHandler *dbms_handler, replication::ReplicationServer &server) {
-  server.rpc_server_.Register<storage::replication::HeartbeatRpc>([dbms_handler](auto *req_reader, auto *res_builder) {
-    spdlog::debug("Received HeartbeatRpc");
-    InMemoryReplicationHandlers::HeartbeatHandler(dbms_handler, req_reader, res_builder);
-  });
-  server.rpc_server_.Register<storage::replication::AppendDeltasRpc>(
-      [dbms_handler](auto *req_reader, auto *res_builder) {
-        spdlog::debug("Received AppendDeltasRpc");
-        InMemoryReplicationHandlers::AppendDeltasHandler(dbms_handler, req_reader, res_builder);
+void InMemoryReplicationHandlers::Register(dbms::DbmsHandler *dbms_handler, replication::RoleReplicaData &data) {
+  auto &server = *data.server;
+  server.rpc_server_.Register<storage::replication::HeartbeatRpc>(
+      [&data, dbms_handler](auto *req_reader, auto *res_builder) {
+        spdlog::debug("Received HeartbeatRpc");
+        InMemoryReplicationHandlers::HeartbeatHandler(dbms_handler, data.uuid_, req_reader, res_builder);
+      });
+  server.rpc_server_.Register<storage::replication::AppendDeltasRpc>(
+      [&data, dbms_handler](auto *req_reader, auto *res_builder) {
+        spdlog::debug("Received AppendDeltasRpc");
+        InMemoryReplicationHandlers::AppendDeltasHandler(dbms_handler, data.uuid_, req_reader, res_builder);
+      });
+  server.rpc_server_.Register<storage::replication::SnapshotRpc>(
+      [&data, dbms_handler](auto *req_reader, auto *res_builder) {
+        spdlog::debug("Received SnapshotRpc");
+        InMemoryReplicationHandlers::SnapshotHandler(dbms_handler, data.uuid_, req_reader, res_builder);
+      });
+  server.rpc_server_.Register<storage::replication::WalFilesRpc>(
+      [&data, dbms_handler](auto *req_reader, auto *res_builder) {
+        spdlog::debug("Received WalFilesRpc");
+        InMemoryReplicationHandlers::WalFilesHandler(dbms_handler, data.uuid_, req_reader, res_builder);
+      });
+  server.rpc_server_.Register<storage::replication::CurrentWalRpc>(
+      [&data, dbms_handler](auto *req_reader, auto *res_builder) {
+        spdlog::debug("Received CurrentWalRpc");
+        InMemoryReplicationHandlers::CurrentWalHandler(dbms_handler, data.uuid_, req_reader, res_builder);
+      });
+  server.rpc_server_.Register<storage::replication::TimestampRpc>(
+      [&data, dbms_handler](auto *req_reader, auto *res_builder) {
+        spdlog::debug("Received TimestampRpc");
+        InMemoryReplicationHandlers::TimestampHandler(dbms_handler, data.uuid_, req_reader, res_builder);
+      });
+  server.rpc_server_.Register<replication_coordination_glue::SwapMainUUIDRpc>(
+      [&data, dbms_handler](auto *req_reader, auto *res_builder) {
+        spdlog::debug("Received SwapMainUUIDHandler");
+        InMemoryReplicationHandlers::SwapMainUUIDHandler(dbms_handler, data, req_reader, res_builder);
       });
-  server.rpc_server_.Register<storage::replication::SnapshotRpc>([dbms_handler](auto *req_reader, auto *res_builder) {
-    spdlog::debug("Received SnapshotRpc");
-    InMemoryReplicationHandlers::SnapshotHandler(dbms_handler, req_reader, res_builder);
-  });
-  server.rpc_server_.Register<storage::replication::WalFilesRpc>([dbms_handler](auto *req_reader, auto *res_builder) {
-    spdlog::debug("Received WalFilesRpc");
-    InMemoryReplicationHandlers::WalFilesHandler(dbms_handler, req_reader, res_builder);
-  });
-  server.rpc_server_.Register<storage::replication::CurrentWalRpc>([dbms_handler](auto *req_reader, auto *res_builder) {
-    spdlog::debug("Received CurrentWalRpc");
-    InMemoryReplicationHandlers::CurrentWalHandler(dbms_handler, req_reader, res_builder);
-  });
-  server.rpc_server_.Register<storage::replication::TimestampRpc>([dbms_handler](auto *req_reader, auto *res_builder) {
-    spdlog::debug("Received TimestampRpc");
-    InMemoryReplicationHandlers::TimestampHandler(dbms_handler, req_reader, res_builder);
-  });
 }
 
-void InMemoryReplicationHandlers::HeartbeatHandler(dbms::DbmsHandler *dbms_handler, slk::Reader *req_reader,
-                                                   slk::Builder *res_builder) {
+void InMemoryReplicationHandlers::SwapMainUUIDHandler(dbms::DbmsHandler *dbms_handler,
+                                                      replication::RoleReplicaData &role_replica_data,
+                                                      slk::Reader *req_reader, slk::Builder *res_builder) {
+  if (!dbms_handler->IsReplica()) {
+    spdlog::error("Setting main uuid must be performed on replica.");
+    slk::Save(replication_coordination_glue::SwapMainUUIDRes{false}, res_builder);
+    return;
+  }
+
+  replication_coordination_glue::SwapMainUUIDReq req;
+  slk::Load(&req, req_reader);
+  spdlog::info(fmt::format("Set replica data UUID  to main uuid {}", std::string(req.uuid)));
+  dbms_handler->ReplicationState().TryPersistRoleReplica(role_replica_data.config, req.uuid);
+  role_replica_data.uuid_ = req.uuid;
+
+  slk::Save(replication_coordination_glue::SwapMainUUIDRes{true}, res_builder);
+}
+
+void InMemoryReplicationHandlers::HeartbeatHandler(dbms::DbmsHandler *dbms_handler,
+                                                   const std::optional<utils::UUID> &current_main_uuid,
+                                                   slk::Reader *req_reader, slk::Builder *res_builder) {
   storage::replication::HeartbeatReq req;
   slk::Load(&req, req_reader);
   auto const db_acc = GetDatabaseAccessor(dbms_handler, req.uuid);
-  if (!db_acc) {
+
+  if (!current_main_uuid.has_value() || req.main_uuid != *current_main_uuid) [[unlikely]] {
+    LogWrongMain(current_main_uuid, req.main_uuid, storage::replication::HeartbeatReq::kType.name);
     storage::replication::HeartbeatRes res{false, 0, ""};
     slk::Save(res, res_builder);
     return;
   }
-
   // TODO: this handler is agnostic of InMemory, move to be reused by on-disk
+  if (!db_acc.has_value()) {
+    spdlog::warn("No database accessor");
+    storage::replication::HeartbeatRes res{false, 0, ""};
+    slk::Save(res, res_builder);
+    return;
+  }
   auto const *storage = db_acc->get()->storage();
   storage::replication::HeartbeatRes res{true, storage->repl_storage_state_.last_commit_timestamp_.load(),
                                          std::string{storage->repl_storage_state_.epoch_.id()}};
   slk::Save(res, res_builder);
 }
 
-void InMemoryReplicationHandlers::AppendDeltasHandler(dbms::DbmsHandler *dbms_handler, slk::Reader *req_reader,
-                                                      slk::Builder *res_builder) {
+void InMemoryReplicationHandlers::AppendDeltasHandler(dbms::DbmsHandler *dbms_handler,
+                                                      const std::optional<utils::UUID> &current_main_uuid,
+                                                      slk::Reader *req_reader, slk::Builder *res_builder) {
   storage::replication::AppendDeltasReq req;
   slk::Load(&req, req_reader);
+
+  if (!current_main_uuid.has_value() || req.main_uuid != current_main_uuid) [[unlikely]] {
+    LogWrongMain(current_main_uuid, req.main_uuid, storage::replication::AppendDeltasReq::kType.name);
+    storage::replication::AppendDeltasRes res{false, 0};
+    slk::Save(res, res_builder);
+    return;
+  }
+
   auto db_acc = GetDatabaseAccessor(dbms_handler, req.uuid);
   if (!db_acc) {
     storage::replication::AppendDeltasRes res{false, 0};
@@ -187,8 +239,9 @@ void InMemoryReplicationHandlers::AppendDeltasHandler(dbms::DbmsHandler *dbms_ha
   spdlog::debug("Replication recovery from append deltas finished, replica is now up to date!");
 }
 
-void InMemoryReplicationHandlers::SnapshotHandler(dbms::DbmsHandler *dbms_handler, slk::Reader *req_reader,
-                                                  slk::Builder *res_builder) {
+void InMemoryReplicationHandlers::SnapshotHandler(dbms::DbmsHandler *dbms_handler,
+                                                  const std::optional<utils::UUID> &current_main_uuid,
+                                                  slk::Reader *req_reader, slk::Builder *res_builder) {
   storage::replication::SnapshotReq req;
   slk::Load(&req, req_reader);
   auto db_acc = GetDatabaseAccessor(dbms_handler, req.uuid);
@@ -197,6 +250,12 @@ void InMemoryReplicationHandlers::SnapshotHandler(dbms::DbmsHandler *dbms_handle
     slk::Save(res, res_builder);
     return;
   }
+  if (!current_main_uuid.has_value() || req.main_uuid != current_main_uuid) [[unlikely]] {
+    LogWrongMain(current_main_uuid, req.main_uuid, storage::replication::SnapshotReq::kType.name);
+    storage::replication::SnapshotRes res{false, 0};
+    slk::Save(res, res_builder);
+    return;
+  }
 
   storage::replication::Decoder decoder(req_reader);
 
@@ -270,8 +329,9 @@ void InMemoryReplicationHandlers::SnapshotHandler(dbms::DbmsHandler *dbms_handle
   spdlog::debug("Replication recovery from snapshot finished!");
 }
 
-void InMemoryReplicationHandlers::WalFilesHandler(dbms::DbmsHandler *dbms_handler, slk::Reader *req_reader,
-                                                  slk::Builder *res_builder) {
+void InMemoryReplicationHandlers::WalFilesHandler(dbms::DbmsHandler *dbms_handler,
+                                                  const std::optional<utils::UUID> &current_main_uuid,
+                                                  slk::Reader *req_reader, slk::Builder *res_builder) {
   storage::replication::WalFilesReq req;
   slk::Load(&req, req_reader);
   auto db_acc = GetDatabaseAccessor(dbms_handler, req.uuid);
@@ -280,6 +340,12 @@ void InMemoryReplicationHandlers::WalFilesHandler(dbms::DbmsHandler *dbms_handle
     slk::Save(res, res_builder);
     return;
   }
+  if (!current_main_uuid.has_value() || req.main_uuid != current_main_uuid) [[unlikely]] {
+    LogWrongMain(current_main_uuid, req.main_uuid, storage::replication::WalFilesReq::kType.name);
+    storage::replication::WalFilesRes res{false, 0};
+    slk::Save(res, res_builder);
+    return;
+  }
 
   const auto wal_file_number = req.file_number;
   spdlog::debug("Received WAL files: {}", wal_file_number);
@@ -298,8 +364,9 @@ void InMemoryReplicationHandlers::WalFilesHandler(dbms::DbmsHandler *dbms_handle
   spdlog::debug("Replication recovery from WAL files ended successfully, replica is now up to date!");
 }
 
-void InMemoryReplicationHandlers::CurrentWalHandler(dbms::DbmsHandler *dbms_handler, slk::Reader *req_reader,
-                                                    slk::Builder *res_builder) {
+void InMemoryReplicationHandlers::CurrentWalHandler(dbms::DbmsHandler *dbms_handler,
+                                                    const std::optional<utils::UUID> &current_main_uuid,
+                                                    slk::Reader *req_reader, slk::Builder *res_builder) {
   storage::replication::CurrentWalReq req;
   slk::Load(&req, req_reader);
   auto db_acc = GetDatabaseAccessor(dbms_handler, req.uuid);
@@ -309,6 +376,13 @@ void InMemoryReplicationHandlers::CurrentWalHandler(dbms::DbmsHandler *dbms_hand
     return;
   }
 
+  if (!current_main_uuid.has_value() || req.main_uuid != current_main_uuid) [[unlikely]] {
+    LogWrongMain(current_main_uuid, req.main_uuid, storage::replication::CurrentWalReq::kType.name);
+    storage::replication::CurrentWalRes res{false, 0};
+    slk::Save(res, res_builder);
+    return;
+  }
+
   storage::replication::Decoder decoder(req_reader);
 
   auto *storage = static_cast<storage::InMemoryStorage *>(db_acc->get()->storage());
@@ -370,8 +444,9 @@ void InMemoryReplicationHandlers::LoadWal(storage::InMemoryStorage *storage, sto
   }
 }
 
-void InMemoryReplicationHandlers::TimestampHandler(dbms::DbmsHandler *dbms_handler, slk::Reader *req_reader,
-                                                   slk::Builder *res_builder) {
+void InMemoryReplicationHandlers::TimestampHandler(dbms::DbmsHandler *dbms_handler,
+                                                   const std::optional<utils::UUID> &current_main_uuid,
+                                                   slk::Reader *req_reader, slk::Builder *res_builder) {
   storage::replication::TimestampReq req;
   slk::Load(&req, req_reader);
   auto const db_acc = GetDatabaseAccessor(dbms_handler, req.uuid);
@@ -381,6 +456,13 @@ void InMemoryReplicationHandlers::TimestampHandler(dbms::DbmsHandler *dbms_handl
     return;
   }
 
+  if (!current_main_uuid.has_value() || req.main_uuid != current_main_uuid) [[unlikely]] {
+    LogWrongMain(current_main_uuid, req.main_uuid, storage::replication::TimestampReq::kType.name);
+    storage::replication::CurrentWalRes res{false, 0};
+    slk::Save(res, res_builder);
+    return;
+  }
+
   // TODO: this handler is agnostic of InMemory, move to be reused by on-disk
   auto const *storage = db_acc->get()->storage();
   storage::replication::TimestampRes res{true, storage->repl_storage_state_.last_commit_timestamp_.load()};

src/dbms/inmemory/replication_handlers.hpp

@@ -12,6 +12,7 @@
 #pragma once
 
 #include "replication/replication_server.hpp"
+#include "replication/state.hpp"
 #include "storage/v2/replication/serialization.hpp"
 
 namespace memgraph::storage {
@@ -23,21 +24,30 @@ class DbmsHandler;
 
 class InMemoryReplicationHandlers {
  public:
-  static void Register(dbms::DbmsHandler *dbms_handler, replication::ReplicationServer &server);
+  static void Register(dbms::DbmsHandler *dbms_handler, replication::RoleReplicaData &data);
 
  private:
   // RPC handlers
-  static void HeartbeatHandler(dbms::DbmsHandler *dbms_handler, slk::Reader *req_reader, slk::Builder *res_builder);
+  static void HeartbeatHandler(dbms::DbmsHandler *dbms_handler, const std::optional<utils::UUID> &current_main_uuid,
+                               slk::Reader *req_reader, slk::Builder *res_builder);
 
-  static void AppendDeltasHandler(dbms::DbmsHandler *dbms_handler, slk::Reader *req_reader, slk::Builder *res_builder);
+  static void AppendDeltasHandler(dbms::DbmsHandler *dbms_handler, const std::optional<utils::UUID> &current_main_uuid,
+                                  slk::Reader *req_reader, slk::Builder *res_builder);
 
-  static void SnapshotHandler(dbms::DbmsHandler *dbms_handler, slk::Reader *req_reader, slk::Builder *res_builder);
+  static void SnapshotHandler(dbms::DbmsHandler *dbms_handler, const std::optional<utils::UUID> &current_main_uuid,
+                              slk::Reader *req_reader, slk::Builder *res_builder);
 
-  static void WalFilesHandler(dbms::DbmsHandler *dbms_handler, slk::Reader *req_reader, slk::Builder *res_builder);
+  static void WalFilesHandler(dbms::DbmsHandler *dbms_handler, const std::optional<utils::UUID> &current_main_uuid,
+                              slk::Reader *req_reader, slk::Builder *res_builder);
 
-  static void CurrentWalHandler(dbms::DbmsHandler *dbms_handler, slk::Reader *req_reader, slk::Builder *res_builder);
+  static void CurrentWalHandler(dbms::DbmsHandler *dbms_handler, const std::optional<utils::UUID> &current_main_uuid,
+                                slk::Reader *req_reader, slk::Builder *res_builder);
 
-  static void TimestampHandler(dbms::DbmsHandler *dbms_handler, slk::Reader *req_reader, slk::Builder *res_builder);
+  static void TimestampHandler(dbms::DbmsHandler *dbms_handler, const std::optional<utils::UUID> &current_main_uuid,
+                               slk::Reader *req_reader, slk::Builder *res_builder);
+
+  static void SwapMainUUIDHandler(dbms::DbmsHandler *dbms_handler, replication::RoleReplicaData &role_replica_data,
+                                  slk::Reader *req_reader, slk::Builder *res_builder);
 
   static void LoadWal(storage::InMemoryStorage *storage, storage::replication::Decoder *decoder);
 

src/dbms/inmemory/storage_helper.hpp

@@ -11,10 +11,6 @@
 
 #pragma once
 
-#include <variant>
-
-#include "dbms/constants.hpp"
-#include "dbms/replication_handler.hpp"
 #include "replication/state.hpp"
 #include "storage/v2/config.hpp"
 #include "storage/v2/inmemory/storage.hpp"

src/dbms/replication_client.cpp

@@ -1,43 +0,0 @@
-// Copyright 2024 Memgraph Ltd.
-//
-// Use of this software is governed by the Business Source License
-// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
-// License, and you may not use this file except in compliance with the Business Source License.
-//
-// As of the Change Date specified in that file, in accordance with
-// the Business Source License, use of this software will be governed
-// by the Apache License, Version 2.0, included in the file
-// licenses/APL.txt.
-
-#include "dbms/replication_client.hpp"
-#include "replication/replication_client.hpp"
-
-namespace memgraph::dbms {
-
-void StartReplicaClient(DbmsHandler &dbms_handler, replication::ReplicationClient &client) {
-  // No client error, start instance level client
-  auto const &endpoint = client.rpc_client_.Endpoint();
-  spdlog::trace("Replication client started at: {}:{}", endpoint.address, endpoint.port);
-  client.StartFrequentCheck([&dbms_handler](bool reconnect, replication::ReplicationClient &client) {
-    // Working connection
-    // Check if system needs restoration
-    if (reconnect) {
-      client.state_.WithLock([](auto &state) { state = memgraph::replication::ReplicationClient::State::BEHIND; });
-    }
-#ifdef MG_ENTERPRISE
-    dbms_handler.SystemRestore<true>(client);
-#endif
-    // Check if any database has been left behind
-    dbms_handler.ForEach([&name = client.name_, reconnect](dbms::DatabaseAccess db_acc) {
-      // Specific database <-> replica client
-      db_acc->storage()->repl_storage_state_.WithClient(name, [&](storage::ReplicationStorageClient *client) {
-        if (reconnect || client->State() == storage::replication::ReplicaState::MAYBE_BEHIND) {
-          // Database <-> replica might be behind, check and recover
-          client->TryCheckReplicaStateAsync(db_acc->storage(), db_acc);
-        }
-      });
-    });
-  });
-}  // namespace memgraph::dbms
-
-}  // namespace memgraph::dbms

src/dbms/replication_handler.cpp

@@ -1,400 +0,0 @@
-// Copyright 2024 Memgraph Ltd.
-//
-// Use of this software is governed by the Business Source License
-// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
-// License, and you may not use this file except in compliance with the Business Source License.
-//
-// As of the Change Date specified in that file, in accordance with
-// the Business Source License, use of this software will be governed
-// by the Apache License, Version 2.0, included in the file
-// licenses/APL.txt.
-
-#include "dbms/replication_handler.hpp"
-
-#include <algorithm>
-
-#include "dbms/constants.hpp"
-#include "dbms/dbms_handler.hpp"
-#include "dbms/global.hpp"
-#include "dbms/inmemory/replication_handlers.hpp"
-#include "dbms/replication_client.hpp"
-#include "dbms/utils.hpp"
-#include "replication/messages.hpp"
-#include "replication/state.hpp"
-#include "spdlog/spdlog.h"
-#include "storage/v2/config.hpp"
-#include "storage/v2/replication/rpc.hpp"
-#include "utils/on_scope_exit.hpp"
-
-using memgraph::replication::RoleMainData;
-using memgraph::replication::RoleReplicaData;
-
-namespace memgraph::dbms {
-
-namespace {
-
-std::string RegisterReplicaErrorToString(RegisterReplicaError error) {
-  switch (error) {
-    using enum RegisterReplicaError;
-    case NAME_EXISTS:
-      return "NAME_EXISTS";
-    case END_POINT_EXISTS:
-      return "END_POINT_EXISTS";
-    case CONNECTION_FAILED:
-      return "CONNECTION_FAILED";
-    case COULD_NOT_BE_PERSISTED:
-      return "COULD_NOT_BE_PERSISTED";
-  }
-}
-}  // namespace
-
-ReplicationHandler::ReplicationHandler(DbmsHandler &dbms_handler) : dbms_handler_(dbms_handler) {}
-
-bool ReplicationHandler::SetReplicationRoleMain() {
-  auto const main_handler = [](RoleMainData &) {
-    // If we are already MAIN, we don't want to change anything
-    return false;
-  };
-
-  auto const replica_handler = [this](RoleReplicaData const &) {
-    return memgraph::dbms::DoReplicaToMainPromotion(dbms_handler_);
-  };
-
-  // TODO: under lock
-  return std::visit(utils::Overloaded{main_handler, replica_handler},
-                    dbms_handler_.ReplicationState().ReplicationData());
-}
-
-bool ReplicationHandler::SetReplicationRoleReplica(const memgraph::replication::ReplicationServerConfig &config) {
-  // We don't want to restart the server if we're already a REPLICA
-  if (dbms_handler_.ReplicationState().IsReplica()) {
-    return false;
-  }
-
-  // TODO StorageState needs to be synched. Could have a dangling reference if someone adds a database as we are
-  //      deleting the replica.
-  // Remove database specific clients
-  dbms_handler_.ForEach([&](DatabaseAccess db_acc) {
-    auto *storage = db_acc->storage();
-    storage->repl_storage_state_.replication_clients_.WithLock([](auto &clients) { clients.clear(); });
-  });
-  // Remove instance level clients
-  std::get<RoleMainData>(dbms_handler_.ReplicationState().ReplicationData()).registered_replicas_.clear();
-
-  // Creates the server
-  dbms_handler_.ReplicationState().SetReplicationRoleReplica(config);
-
-  // Start
-  const auto success =
-      std::visit(utils::Overloaded{[](RoleMainData const &) {
-                                     // ASSERT
-                                     return false;
-                                   },
-                                   [this](RoleReplicaData const &data) { return StartRpcServer(dbms_handler_, data); }},
-                 dbms_handler_.ReplicationState().ReplicationData());
-  // TODO Handle error (restore to main?)
-  return success;
-}
-
-auto ReplicationHandler::RegisterReplica(const memgraph::replication::ReplicationClientConfig &config)
-    -> memgraph::utils::BasicResult<RegisterReplicaError> {
-  MG_ASSERT(dbms_handler_.ReplicationState().IsMain(), "Only main instance can register a replica!");
-
-  auto instance_client = dbms_handler_.ReplicationState().RegisterReplica(config);
-  if (instance_client.HasError()) {
-    switch (instance_client.GetError()) {
-      case memgraph::replication::RegisterReplicaError::NOT_MAIN:
-        MG_ASSERT(false, "Only main instance can register a replica!");
-        return {};
-      case memgraph::replication::RegisterReplicaError::NAME_EXISTS:
-        return memgraph::dbms::RegisterReplicaError::NAME_EXISTS;
-      case memgraph::replication::RegisterReplicaError::END_POINT_EXISTS:
-        return memgraph::dbms::RegisterReplicaError::END_POINT_EXISTS;
-      case memgraph::replication::RegisterReplicaError::COULD_NOT_BE_PERSISTED:
-        return memgraph::dbms::RegisterReplicaError::COULD_NOT_BE_PERSISTED;
-      case memgraph::replication::RegisterReplicaError::SUCCESS:
-        break;
-    }
-  }
-
-  if (!allow_mt_repl && dbms_handler_.All().size() > 1) {
-    spdlog::warn("Multi-tenant replication is currently not supported!");
-  }
-
-#ifdef MG_ENTERPRISE
-  // Update system before enabling individual storage <-> replica clients
-  dbms_handler_.SystemRestore(*instance_client.GetValue());
-#endif
-
-  const auto dbms_error = memgraph::dbms::HandleErrorOnReplicaClient(instance_client);
-  if (dbms_error.has_value()) {
-    return *dbms_error;
-  }
-  auto &instance_client_ptr = instance_client.GetValue();
-  const bool all_clients_good = memgraph::dbms::RegisterAllDatabasesClients(dbms_handler_, *instance_client_ptr);
-
-  // NOTE Currently if any databases fails, we revert back
-  if (!all_clients_good) {
-    spdlog::error("Failed to register all databases on the REPLICA \"{}\"", config.name);
-    UnregisterReplica(config.name);
-    return RegisterReplicaError::CONNECTION_FAILED;
-  }
-
-  // No client error, start instance level client
-  StartReplicaClient(dbms_handler_, *instance_client.GetValue());
-  return {};
-}
-
-auto ReplicationHandler::UnregisterReplica(std::string_view name) -> UnregisterReplicaResult {
-  auto const replica_handler = [](RoleReplicaData const &) -> UnregisterReplicaResult {
-    return UnregisterReplicaResult::NOT_MAIN;
-  };
-  auto const main_handler = [this, name](RoleMainData &mainData) -> UnregisterReplicaResult {
-    if (!dbms_handler_.ReplicationState().TryPersistUnregisterReplica(name)) {
-      return UnregisterReplicaResult::COULD_NOT_BE_PERSISTED;
-    }
-    // Remove database specific clients
-    dbms_handler_.ForEach([name](DatabaseAccess db_acc) {
-      db_acc->storage()->repl_storage_state_.replication_clients_.WithLock([&name](auto &clients) {
-        std::erase_if(clients, [name](const auto &client) { return client->Name() == name; });
-      });
-    });
-    // Remove instance level clients
-    auto const n_unregistered =
-        std::erase_if(mainData.registered_replicas_, [name](auto const &client) { return client.name_ == name; });
-    return n_unregistered != 0 ? UnregisterReplicaResult::SUCCESS : UnregisterReplicaResult::CAN_NOT_UNREGISTER;
-  };
-
-  return std::visit(utils::Overloaded{main_handler, replica_handler},
-                    dbms_handler_.ReplicationState().ReplicationData());
-}
-
-auto ReplicationHandler::GetRole() const -> memgraph::replication::ReplicationRole {
-  return dbms_handler_.ReplicationState().GetRole();
-}
-
-bool ReplicationHandler::IsMain() const { return dbms_handler_.ReplicationState().IsMain(); }
-
-bool ReplicationHandler::IsReplica() const { return dbms_handler_.ReplicationState().IsReplica(); }
-
-// Per storage
-// NOTE Storage will connect to all replicas. Future work might change this
-void RestoreReplication(replication::ReplicationState &repl_state, DatabaseAccess db_acc) {
-  spdlog::info("Restoring replication role.");
-
-  /// MAIN
-  auto const recover_main = [db_acc = std::move(db_acc)](RoleMainData &mainData) mutable {  // NOLINT
-    // Each individual client has already been restored and started. Here we just go through each database and start its
-    // client
-    for (auto &instance_client : mainData.registered_replicas_) {
-      spdlog::info("Replica {} restoration started for {}.", instance_client.name_, db_acc->name());
-      const auto &ret = db_acc->storage()->repl_storage_state_.replication_clients_.WithLock(
-          [&, db_acc](auto &storage_clients) mutable -> utils::BasicResult<RegisterReplicaError> {
-            auto client = std::make_unique<storage::ReplicationStorageClient>(instance_client);
-            auto *storage = db_acc->storage();
-            client->Start(storage, std::move(db_acc));
-            // After start the storage <-> replica state should be READY or RECOVERING (if correctly started)
-            // MAYBE_BEHIND isn't a statement of the current state, this is the default value
-            // Failed to start due to branching of MAIN and REPLICA
-            if (client->State() == storage::replication::ReplicaState::MAYBE_BEHIND) {
-              spdlog::warn("Connection failed when registering replica {}. Replica will still be registered.",
-                           instance_client.name_);
-            }
-            storage_clients.push_back(std::move(client));
-            return {};
-          });
-
-      if (ret.HasError()) {
-        MG_ASSERT(RegisterReplicaError::CONNECTION_FAILED != ret.GetError());
-        LOG_FATAL("Failure when restoring replica {}: {}.", instance_client.name_,
-                  RegisterReplicaErrorToString(ret.GetError()));
-      }
-      spdlog::info("Replica {} restored for {}.", instance_client.name_, db_acc->name());
-    }
-    spdlog::info("Replication role restored to MAIN.");
-  };
-
-  /// REPLICA
-  auto const recover_replica = [](RoleReplicaData const &data) { /*nothing to do*/ };
-
-  std::visit(
-      utils::Overloaded{
-          recover_main,
-          recover_replica,
-      },
-      repl_state.ReplicationData());
-}
-
-namespace system_replication {
-#ifdef MG_ENTERPRISE
-void SystemHeartbeatHandler(const uint64_t ts, slk::Reader *req_reader, slk::Builder *res_builder) {
-  replication::SystemHeartbeatReq req;
-  replication::SystemHeartbeatReq::Load(&req, req_reader);
-
-  replication::SystemHeartbeatRes res(ts);
-  memgraph::slk::Save(res, res_builder);
-}
-
-void CreateDatabaseHandler(DbmsHandler &dbms_handler, slk::Reader *req_reader, slk::Builder *res_builder) {
-  memgraph::storage::replication::CreateDatabaseReq req;
-  memgraph::slk::Load(&req, req_reader);
-
-  using memgraph::storage::replication::CreateDatabaseRes;
-  CreateDatabaseRes res(CreateDatabaseRes::Result::FAILURE);
-
-  // Note: No need to check epoch, recovery mechanism is done by a full uptodate snapshot
-  //       of the set of databases. Hence no history exists to maintain regarding epoch change.
-  //       If MAIN has changed we need to check this new group_timestamp is consistent with
-  //       what we have so far.
-
-  if (req.expected_group_timestamp != dbms_handler.LastCommitedTS()) {
-    spdlog::debug("CreateDatabaseHandler: bad expected timestamp {},{}", req.expected_group_timestamp,
-                  dbms_handler.LastCommitedTS());
-    memgraph::slk::Save(res, res_builder);
-    return;
-  }
-
-  try {
-    // Create new
-    auto new_db = dbms_handler.Update(req.config);
-    if (new_db.HasValue()) {
-      // Successfully create db
-      dbms_handler.SetLastCommitedTS(req.new_group_timestamp);
-      res = CreateDatabaseRes(CreateDatabaseRes::Result::SUCCESS);
-      spdlog::debug("CreateDatabaseHandler: SUCCESS updated LCTS to {}", req.new_group_timestamp);
-    }
-  } catch (...) {
-    // Failure
-  }
-
-  memgraph::slk::Save(res, res_builder);
-}
-
-void DropDatabaseHandler(DbmsHandler &dbms_handler, slk::Reader *req_reader, slk::Builder *res_builder) {
-  memgraph::storage::replication::DropDatabaseReq req;
-  memgraph::slk::Load(&req, req_reader);
-
-  using memgraph::storage::replication::DropDatabaseRes;
-  DropDatabaseRes res(DropDatabaseRes::Result::FAILURE);
-
-  // Note: No need to check epoch, recovery mechanism is done by a full uptodate snapshot
-  //       of the set of databases. Hence no history exists to maintain regarding epoch change.
-  //       If MAIN has changed we need to check this new group_timestamp is consistent with
-  //       what we have so far.
-
-  if (req.expected_group_timestamp != dbms_handler.LastCommitedTS()) {
-    spdlog::debug("DropDatabaseHandler: bad expected timestamp {},{}", req.expected_group_timestamp,
-                  dbms_handler.LastCommitedTS());
-    memgraph::slk::Save(res, res_builder);
-    return;
-  }
-
-  try {
-    // NOTE: Single communication channel can exist at a time, no other database can be deleted/created at the moment.
-    auto new_db = dbms_handler.Delete(req.uuid);
-    if (new_db.HasError()) {
-      if (new_db.GetError() == DeleteError::NON_EXISTENT) {
-        // Nothing to drop
-        dbms_handler.SetLastCommitedTS(req.new_group_timestamp);
-        res = DropDatabaseRes(DropDatabaseRes::Result::NO_NEED);
-      }
-    } else {
-      // Successfully drop db
-      dbms_handler.SetLastCommitedTS(req.new_group_timestamp);
-      res = DropDatabaseRes(DropDatabaseRes::Result::SUCCESS);
-      spdlog::debug("DropDatabaseHandler: SUCCESS updated LCTS to {}", req.new_group_timestamp);
-    }
-  } catch (...) {
-    // Failure
-  }
-
-  memgraph::slk::Save(res, res_builder);
-}
-
-void SystemRecoveryHandler(DbmsHandler &dbms_handler, slk::Reader *req_reader, slk::Builder *res_builder) {
-  // TODO Speed up
-  memgraph::storage::replication::SystemRecoveryReq req;
-  memgraph::slk::Load(&req, req_reader);
-
-  using memgraph::storage::replication::SystemRecoveryRes;
-  SystemRecoveryRes res(SystemRecoveryRes::Result::FAILURE);
-
-  utils::OnScopeExit send_on_exit([&]() { memgraph::slk::Save(res, res_builder); });
-
-  // Get all current dbs
-  auto old = dbms_handler.All();
-
-  // Check/create the incoming dbs
-  for (const auto &config : req.database_configs) {
-    // Missing db
-    try {
-      if (dbms_handler.Update(config).HasError()) {
-        spdlog::debug("SystemRecoveryHandler: Failed to update database \"{}\".", config.name);
-        return;  // Send failure on exit
-      }
-    } catch (const UnknownDatabaseException &) {
-      spdlog::debug("SystemRecoveryHandler: UnknownDatabaseException");
-      return;  // Send failure on exit
-    }
-    const auto it = std::find(old.begin(), old.end(), config.name);
-    if (it != old.end()) old.erase(it);
-  }
-
-  // Delete all the leftover old dbs
-  for (const auto &remove_db : old) {
-    const auto del = dbms_handler.Delete(remove_db);
-    if (del.HasError()) {
-      // Some errors are not terminal
-      if (del.GetError() == DeleteError::DEFAULT_DB || del.GetError() == DeleteError::NON_EXISTENT) {
-        spdlog::debug("SystemRecoveryHandler: Dropped database \"{}\".", remove_db);
-        continue;
-      }
-      spdlog::debug("SystemRecoveryHandler: Failed to drop database \"{}\".", remove_db);
-      return;  // Send failure on exit
-    }
-  }
-  // Successfully recovered
-  dbms_handler.SetLastCommitedTS(req.forced_group_timestamp);
-  spdlog::debug("SystemRecoveryHandler: SUCCESS updated LCTS to {}", req.forced_group_timestamp);
-  res = SystemRecoveryRes(SystemRecoveryRes::Result::SUCCESS);
-}
-#endif
-
-void Register(replication::RoleReplicaData const &data, dbms::DbmsHandler &dbms_handler) {
-#ifdef MG_ENTERPRISE
-  data.server->rpc_server_.Register<replication::SystemHeartbeatRpc>(
-      [&dbms_handler](auto *req_reader, auto *res_builder) {
-        spdlog::debug("Received SystemHeartbeatRpc");
-        SystemHeartbeatHandler(dbms_handler.LastCommitedTS(), req_reader, res_builder);
-      });
-  data.server->rpc_server_.Register<storage::replication::CreateDatabaseRpc>(
-      [&dbms_handler](auto *req_reader, auto *res_builder) {
-        spdlog::debug("Received CreateDatabaseRpc");
-        CreateDatabaseHandler(dbms_handler, req_reader, res_builder);
-      });
-  data.server->rpc_server_.Register<storage::replication::DropDatabaseRpc>(
-      [&dbms_handler](auto *req_reader, auto *res_builder) {
-        spdlog::debug("Received DropDatabaseRpc");
-        DropDatabaseHandler(dbms_handler, req_reader, res_builder);
-      });
-  data.server->rpc_server_.Register<storage::replication::SystemRecoveryRpc>(
-      [&dbms_handler](auto *req_reader, auto *res_builder) {
-        spdlog::debug("Received SystemRecoveryRpc");
-        SystemRecoveryHandler(dbms_handler, req_reader, res_builder);
-      });
-#endif
-}
-}  // namespace system_replication
-
-bool StartRpcServer(DbmsHandler &dbms_handler, const replication::RoleReplicaData &data) {
-  // Register handlers
-  InMemoryReplicationHandlers::Register(&dbms_handler, *data.server);
-  system_replication::Register(data, dbms_handler);
-  // Start server
-  if (!data.server->Start()) {
-    spdlog::error("Unable to start the replication server.");
-    return false;
-  }
-  return true;
-}
-}  // namespace memgraph::dbms

src/dbms/replication_handler.hpp

@@ -1,82 +0,0 @@
-// Copyright 2024 Memgraph Ltd.
-//
-// Use of this software is governed by the Business Source License
-// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
-// License, and you may not use this file except in compliance with the Business Source License.
-//
-// As of the Change Date specified in that file, in accordance with
-// the Business Source License, use of this software will be governed
-// by the Apache License, Version 2.0, included in the file
-// licenses/APL.txt.
-
-#pragma once
-
-#include "dbms/database.hpp"
-#include "replication/role.hpp"
-#include "utils/result.hpp"
-
-namespace memgraph::replication {
-struct ReplicationState;
-struct ReplicationServerConfig;
-struct ReplicationClientConfig;
-}  // namespace memgraph::replication
-
-namespace memgraph::dbms {
-
-class DbmsHandler;
-
-enum class RegisterReplicaError : uint8_t { NAME_EXISTS, END_POINT_EXISTS, CONNECTION_FAILED, COULD_NOT_BE_PERSISTED };
-
-enum class UnregisterReplicaResult : uint8_t {
-  NOT_MAIN,
-  COULD_NOT_BE_PERSISTED,
-  CAN_NOT_UNREGISTER,
-  SUCCESS,
-};
-
-/// A handler type that keep in sync current ReplicationState and the MAIN/REPLICA-ness of Storage
-/// TODO: extend to do multiple storages
-struct ReplicationHandler {
-  explicit ReplicationHandler(DbmsHandler &dbms_handler);
-
-  // as REPLICA, become MAIN
-  bool SetReplicationRoleMain();
-
-  // as MAIN, become REPLICA
-  bool SetReplicationRoleReplica(const memgraph::replication::ReplicationServerConfig &config);
-
-  // as MAIN, define and connect to REPLICAs
-  auto RegisterReplica(const memgraph::replication::ReplicationClientConfig &config)
-      -> utils::BasicResult<RegisterReplicaError>;
-
-  // as MAIN, remove a REPLICA connection
-  auto UnregisterReplica(std::string_view name) -> UnregisterReplicaResult;
-
-  // Helper pass-through (TODO: remove)
-  auto GetRole() const -> memgraph::replication::ReplicationRole;
-  bool IsMain() const;
-  bool IsReplica() const;
-
- private:
-  DbmsHandler &dbms_handler_;
-};
-
-/// A handler type that keep in sync current ReplicationState and the MAIN/REPLICA-ness of Storage
-/// TODO: extend to do multiple storages
-void RestoreReplication(replication::ReplicationState &repl_state, DatabaseAccess db_acc);
-
-namespace system_replication {
-// System handlers
-#ifdef MG_ENTERPRISE
-void CreateDatabaseHandler(DbmsHandler &dbms_handler, slk::Reader *req_reader, slk::Builder *res_builder);
-void SystemHeartbeatHandler(uint64_t ts, slk::Reader *req_reader, slk::Builder *res_builder);
-void SystemRecoveryHandler(DbmsHandler &dbms_handler, slk::Reader *req_reader, slk::Builder *res_builder);
-#endif
-
-/// Register all DBMS level RPC handlers
-void Register(replication::RoleReplicaData const &data, DbmsHandler &dbms_handler);
-}  // namespace system_replication
-
-bool StartRpcServer(DbmsHandler &dbms_handler, const replication::RoleReplicaData &data);
-
-}  // namespace memgraph::dbms

src/dbms/replication_handlers.cpp

@@ -0,0 +1,205 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#include "dbms/replication_handlers.hpp"
+
+#include "dbms/database.hpp"
+#include "dbms/dbms_handler.hpp"
+#include "storage/v2/storage.hpp"
+#include "system/state.hpp"
+
+namespace memgraph::dbms {
+
+#ifdef MG_ENTERPRISE
+
+void CreateDatabaseHandler(memgraph::system::ReplicaHandlerAccessToState &system_state_access,
+                           const std::optional<utils::UUID> &current_main_uuid, DbmsHandler &dbms_handler,
+                           slk::Reader *req_reader, slk::Builder *res_builder) {
+  using memgraph::storage::replication::CreateDatabaseRes;
+  CreateDatabaseRes res(CreateDatabaseRes::Result::FAILURE);
+
+  // Ignore if no license
+  if (!license::global_license_checker.IsEnterpriseValidFast()) {
+    spdlog::error("Handling CreateDatabase, an enterprise RPC message, without license.");
+    memgraph::slk::Save(res, res_builder);
+    return;
+  }
+
+  memgraph::storage::replication::CreateDatabaseReq req;
+  memgraph::slk::Load(&req, req_reader);
+
+  if (!current_main_uuid.has_value() || req.main_uuid != current_main_uuid) [[unlikely]] {
+    LogWrongMain(current_main_uuid, req.main_uuid, memgraph::storage::replication::CreateDatabaseReq::kType.name);
+    memgraph::slk::Save(res, res_builder);
+    return;
+  }
+
+  // Note: No need to check epoch, recovery mechanism is done by a full uptodate snapshot
+  //       of the set of databases. Hence no history exists to maintain regarding epoch change.
+  //       If MAIN has changed we need to check this new group_timestamp is consistent with
+  //       what we have so far.
+
+  if (req.expected_group_timestamp != system_state_access.LastCommitedTS()) {
+    spdlog::debug("CreateDatabaseHandler: bad expected timestamp {},{}", req.expected_group_timestamp,
+                  system_state_access.LastCommitedTS());
+    memgraph::slk::Save(res, res_builder);
+    return;
+  }
+
+  try {
+    // Create new
+    auto new_db = dbms_handler.Update(req.config);
+    if (new_db.HasValue()) {
+      // Successfully create db
+      system_state_access.SetLastCommitedTS(req.new_group_timestamp);
+      res = CreateDatabaseRes(CreateDatabaseRes::Result::SUCCESS);
+      spdlog::debug("CreateDatabaseHandler: SUCCESS updated LCTS to {}", req.new_group_timestamp);
+    }
+  } catch (...) {
+    // Failure
+  }
+
+  memgraph::slk::Save(res, res_builder);
+}
+
+void DropDatabaseHandler(memgraph::system::ReplicaHandlerAccessToState &system_state_access,
+                         const std::optional<utils::UUID> &current_main_uuid, DbmsHandler &dbms_handler,
+                         slk::Reader *req_reader, slk::Builder *res_builder) {
+  using memgraph::storage::replication::DropDatabaseRes;
+  DropDatabaseRes res(DropDatabaseRes::Result::FAILURE);
+
+  // Ignore if no license
+  if (!license::global_license_checker.IsEnterpriseValidFast()) {
+    spdlog::error("Handling DropDatabase, an enterprise RPC message, without license.");
+    memgraph::slk::Save(res, res_builder);
+    return;
+  }
+
+  memgraph::storage::replication::DropDatabaseReq req;
+  memgraph::slk::Load(&req, req_reader);
+
+  if (!current_main_uuid.has_value() || req.main_uuid != current_main_uuid) [[unlikely]] {
+    LogWrongMain(current_main_uuid, req.main_uuid, memgraph::storage::replication::DropDatabaseReq::kType.name);
+    memgraph::slk::Save(res, res_builder);
+    return;
+  }
+
+  // Note: No need to check epoch, recovery mechanism is done by a full uptodate snapshot
+  //       of the set of databases. Hence no history exists to maintain regarding epoch change.
+  //       If MAIN has changed we need to check this new group_timestamp is consistent with
+  //       what we have so far.
+
+  if (req.expected_group_timestamp != system_state_access.LastCommitedTS()) {
+    spdlog::debug("DropDatabaseHandler: bad expected timestamp {},{}", req.expected_group_timestamp,
+                  system_state_access.LastCommitedTS());
+    memgraph::slk::Save(res, res_builder);
+    return;
+  }
+
+  try {
+    // NOTE: Single communication channel can exist at a time, no other database can be deleted/created at the moment.
+    auto new_db = dbms_handler.Delete(req.uuid);
+    if (new_db.HasError()) {
+      if (new_db.GetError() == DeleteError::NON_EXISTENT) {
+        // Nothing to drop
+        system_state_access.SetLastCommitedTS(req.new_group_timestamp);
+        res = DropDatabaseRes(DropDatabaseRes::Result::NO_NEED);
+      }
+    } else {
+      // Successfully drop db
+      system_state_access.SetLastCommitedTS(req.new_group_timestamp);
+      res = DropDatabaseRes(DropDatabaseRes::Result::SUCCESS);
+      spdlog::debug("DropDatabaseHandler: SUCCESS updated LCTS to {}", req.new_group_timestamp);
+    }
+  } catch (...) {
+    // Failure
+  }
+
+  memgraph::slk::Save(res, res_builder);
+}
+
+bool SystemRecoveryHandler(DbmsHandler &dbms_handler, const std::vector<storage::SalientConfig> &database_configs) {
+  /*
+   * NO LICENSE
+   */
+  if (!license::global_license_checker.IsEnterpriseValidFast()) {
+    spdlog::error("Handling SystemRecovery, an enterprise RPC message, without license.");
+    for (const auto &config : database_configs) {
+      // Only handle default DB
+      if (config.name != kDefaultDB) continue;
+      try {
+        if (dbms_handler.Update(config).HasError()) {
+          return false;
+        }
+      } catch (const UnknownDatabaseException &) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  /*
+   * MULTI-TENANCY
+   */
+  // Get all current dbs
+  auto old = dbms_handler.All();
+  // Check/create the incoming dbs
+  for (const auto &config : database_configs) {
+    // Missing db
+    try {
+      if (dbms_handler.Update(config).HasError()) {
+        spdlog::debug("SystemRecoveryHandler: Failed to update database \"{}\".", config.name);
+        return false;
+      }
+    } catch (const UnknownDatabaseException &) {
+      spdlog::debug("SystemRecoveryHandler: UnknownDatabaseException");
+      return false;
+    }
+    const auto it = std::find(old.begin(), old.end(), config.name);
+    if (it != old.end()) old.erase(it);
+  }
+
+  // Delete all the leftover old dbs
+  for (const auto &remove_db : old) {
+    const auto del = dbms_handler.Delete(remove_db);
+    if (del.HasError()) {
+      // Some errors are not terminal
+      if (del.GetError() == DeleteError::DEFAULT_DB || del.GetError() == DeleteError::NON_EXISTENT) {
+        spdlog::debug("SystemRecoveryHandler: Dropped database \"{}\".", remove_db);
+        continue;
+      }
+      spdlog::debug("SystemRecoveryHandler: Failed to drop database \"{}\".", remove_db);
+      return false;
+    }
+  }
+
+  /*
+   * SUCCESS
+   */
+  return true;
+}
+
+void Register(replication::RoleReplicaData const &data, system::ReplicaHandlerAccessToState &system_state_access,
+              dbms::DbmsHandler &dbms_handler) {
+  // NOTE: Register even without license as the user could add a license at run-time
+  data.server->rpc_server_.Register<storage::replication::CreateDatabaseRpc>(
+      [&data, system_state_access, &dbms_handler](auto *req_reader, auto *res_builder) mutable {
+        spdlog::debug("Received CreateDatabaseRpc");
+        CreateDatabaseHandler(system_state_access, data.uuid_, dbms_handler, req_reader, res_builder);
+      });
+  data.server->rpc_server_.Register<storage::replication::DropDatabaseRpc>(
+      [&data, system_state_access, &dbms_handler](auto *req_reader, auto *res_builder) mutable {
+        spdlog::debug("Received DropDatabaseRpc");
+        DropDatabaseHandler(system_state_access, data.uuid_, dbms_handler, req_reader, res_builder);
+      });
+}
+#endif
+}  // namespace memgraph::dbms

src/dbms/replication_handlers.hpp

@@ -0,0 +1,42 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include "dbms/dbms_handler.hpp"
+#include "replication/state.hpp"
+#include "slk/streams.hpp"
+#include "system/state.hpp"
+
+namespace memgraph::dbms {
+
+#ifdef MG_ENTERPRISE
+
+inline void LogWrongMain(const std::optional<utils::UUID> &current_main_uuid, const utils::UUID &main_req_id,
+                         std::string_view rpc_req) {
+  spdlog::error("Received {} with main_id: {} != current_main_uuid: {}", rpc_req, std::string(main_req_id),
+                current_main_uuid.has_value() ? std::string(current_main_uuid.value()) : "");
+}
+
+// RPC handlers
+void CreateDatabaseHandler(memgraph::system::ReplicaHandlerAccessToState &system_state_access,
+                           const std::optional<utils::UUID> &current_main_uuid, DbmsHandler &dbms_handler,
+                           slk::Reader *req_reader, slk::Builder *res_builder);
+void DropDatabaseHandler(memgraph::system::ReplicaHandlerAccessToState &system_state_access,
+                         const std::optional<utils::UUID> &current_main_uuid, DbmsHandler &dbms_handler,
+                         slk::Reader *req_reader, slk::Builder *res_builder);
+bool SystemRecoveryHandler(DbmsHandler &dbms_handler, const std::vector<storage::SalientConfig> &database_configs);
+
+// RPC registration
+void Register(replication::RoleReplicaData const &data, system::ReplicaHandlerAccessToState &system_state_access,
+              dbms::DbmsHandler &dbms_handler);
+#endif
+}  // namespace memgraph::dbms

src/dbms/rpc.cpp

@@ -0,0 +1,122 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#include "dbms/rpc.hpp"
+
+#include "slk/streams.hpp"
+#include "storage/v2/replication/rpc.hpp"
+#include "utils/enum.hpp"
+#include "utils/typeinfo.hpp"
+
+namespace memgraph {
+
+namespace storage::replication {
+
+void CreateDatabaseReq::Save(const CreateDatabaseReq &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self, builder);
+}
+void CreateDatabaseReq::Load(CreateDatabaseReq *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(self, reader);
+}
+void CreateDatabaseRes::Save(const CreateDatabaseRes &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self, builder);
+}
+void CreateDatabaseRes::Load(CreateDatabaseRes *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(self, reader);
+}
+void DropDatabaseReq::Save(const DropDatabaseReq &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self, builder);
+}
+void DropDatabaseReq::Load(DropDatabaseReq *self, memgraph::slk::Reader *reader) { memgraph::slk::Load(self, reader); }
+void DropDatabaseRes::Save(const DropDatabaseRes &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self, builder);
+}
+void DropDatabaseRes::Load(DropDatabaseRes *self, memgraph::slk::Reader *reader) { memgraph::slk::Load(self, reader); }
+
+const utils::TypeInfo CreateDatabaseReq::kType{utils::TypeId::REP_CREATE_DATABASE_REQ, "CreateDatabaseReq", nullptr};
+
+const utils::TypeInfo CreateDatabaseRes::kType{utils::TypeId::REP_CREATE_DATABASE_RES, "CreateDatabaseRes", nullptr};
+
+const utils::TypeInfo DropDatabaseReq::kType{utils::TypeId::REP_DROP_DATABASE_REQ, "DropDatabaseReq", nullptr};
+
+const utils::TypeInfo DropDatabaseRes::kType{utils::TypeId::REP_DROP_DATABASE_RES, "DropDatabaseRes", nullptr};
+
+}  // namespace storage::replication
+
+// Autogenerated SLK serialization code
+namespace slk {
+
+// Serialize code for CreateDatabaseReq
+
+void Save(const memgraph::storage::replication::CreateDatabaseReq &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self.main_uuid, builder);
+  memgraph::slk::Save(self.epoch_id, builder);
+  memgraph::slk::Save(self.expected_group_timestamp, builder);
+  memgraph::slk::Save(self.new_group_timestamp, builder);
+  memgraph::slk::Save(self.config, builder);
+}
+
+void Load(memgraph::storage::replication::CreateDatabaseReq *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(&self->main_uuid, reader);
+  memgraph::slk::Load(&self->epoch_id, reader);
+  memgraph::slk::Load(&self->expected_group_timestamp, reader);
+  memgraph::slk::Load(&self->new_group_timestamp, reader);
+  memgraph::slk::Load(&self->config, reader);
+}
+
+// Serialize code for CreateDatabaseRes
+
+void Save(const memgraph::storage::replication::CreateDatabaseRes &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(utils::EnumToNum<uint8_t>(self.result), builder);
+}
+
+void Load(memgraph::storage::replication::CreateDatabaseRes *self, memgraph::slk::Reader *reader) {
+  uint8_t res = 0;
+  memgraph::slk::Load(&res, reader);
+  if (!utils::NumToEnum(res, self->result)) {
+    throw SlkReaderException("Unexpected result line:{}!", __LINE__);
+  }
+}
+
+// Serialize code for DropDatabaseReq
+
+void Save(const memgraph::storage::replication::DropDatabaseReq &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(self.main_uuid, builder);
+  memgraph::slk::Save(self.epoch_id, builder);
+  memgraph::slk::Save(self.expected_group_timestamp, builder);
+  memgraph::slk::Save(self.new_group_timestamp, builder);
+  memgraph::slk::Save(self.uuid, builder);
+}
+
+void Load(memgraph::storage::replication::DropDatabaseReq *self, memgraph::slk::Reader *reader) {
+  memgraph::slk::Load(&self->main_uuid, reader);
+  memgraph::slk::Load(&self->epoch_id, reader);
+  memgraph::slk::Load(&self->expected_group_timestamp, reader);
+  memgraph::slk::Load(&self->new_group_timestamp, reader);
+  memgraph::slk::Load(&self->uuid, reader);
+}
+
+// Serialize code for DropDatabaseRes
+
+void Save(const memgraph::storage::replication::DropDatabaseRes &self, memgraph::slk::Builder *builder) {
+  memgraph::slk::Save(utils::EnumToNum<uint8_t>(self.result), builder);
+}
+
+void Load(memgraph::storage::replication::DropDatabaseRes *self, memgraph::slk::Reader *reader) {
+  uint8_t res = 0;
+  memgraph::slk::Load(&res, reader);
+  if (!utils::NumToEnum(res, self->result)) {
+    throw SlkReaderException("Unexpected result line:{}!", __LINE__);
+  }
+}
+
+}  // namespace slk
+}  // namespace memgraph

src/dbms/rpc.hpp

@@ -0,0 +1,122 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <cstdint>
+#include <string>
+#include <utility>
+
+#include "rpc/messages.hpp"
+#include "slk/streams.hpp"
+#include "storage/v2/config.hpp"
+#include "utils/uuid.hpp"
+
+namespace memgraph::storage::replication {
+
+struct CreateDatabaseReq {
+  static const utils::TypeInfo kType;
+  static const utils::TypeInfo &GetTypeInfo() { return kType; }
+
+  static void Load(CreateDatabaseReq *self, memgraph::slk::Reader *reader);
+  static void Save(const CreateDatabaseReq &self, memgraph::slk::Builder *builder);
+  CreateDatabaseReq() = default;
+  CreateDatabaseReq(const utils::UUID &main_uuid, std::string epoch_id, uint64_t expected_group_timestamp,
+                    uint64_t new_group_timestamp, storage::SalientConfig config)
+      : main_uuid(main_uuid),
+        epoch_id(std::move(epoch_id)),
+        expected_group_timestamp{expected_group_timestamp},
+        new_group_timestamp(new_group_timestamp),
+        config(std::move(config)) {}
+
+  utils::UUID main_uuid;
+  std::string epoch_id;
+  uint64_t expected_group_timestamp;
+  uint64_t new_group_timestamp;
+  storage::SalientConfig config;
+};
+
+struct CreateDatabaseRes {
+  static const utils::TypeInfo kType;
+  static const utils::TypeInfo &GetTypeInfo() { return kType; }
+
+  enum class Result : uint8_t { SUCCESS, NO_NEED, FAILURE, /* Leave at end */ N };
+
+  static void Load(CreateDatabaseRes *self, memgraph::slk::Reader *reader);
+  static void Save(const CreateDatabaseRes &self, memgraph::slk::Builder *builder);
+  CreateDatabaseRes() = default;
+  explicit CreateDatabaseRes(Result res) : result(res) {}
+
+  Result result;
+};
+
+using CreateDatabaseRpc = rpc::RequestResponse<CreateDatabaseReq, CreateDatabaseRes>;
+
+struct DropDatabaseReq {
+  static const utils::TypeInfo kType;
+  static const utils::TypeInfo &GetTypeInfo() { return kType; }
+
+  static void Load(DropDatabaseReq *self, memgraph::slk::Reader *reader);
+  static void Save(const DropDatabaseReq &self, memgraph::slk::Builder *builder);
+  DropDatabaseReq() = default;
+  DropDatabaseReq(const utils::UUID &main_uuid, std::string epoch_id, uint64_t expected_group_timestamp,
+                  uint64_t new_group_timestamp, const utils::UUID &uuid)
+      : main_uuid(main_uuid),
+        epoch_id(std::move(epoch_id)),
+        expected_group_timestamp{expected_group_timestamp},
+        new_group_timestamp(new_group_timestamp),
+        uuid(uuid) {}
+
+  utils::UUID main_uuid;
+  std::string epoch_id;
+  uint64_t expected_group_timestamp;
+  uint64_t new_group_timestamp;
+  utils::UUID uuid;
+};
+
+struct DropDatabaseRes {
+  static const utils::TypeInfo kType;
+  static const utils::TypeInfo &GetTypeInfo() { return kType; }
+
+  enum class Result : uint8_t { SUCCESS, NO_NEED, FAILURE, /* Leave at end */ N };
+
+  static void Load(DropDatabaseRes *self, memgraph::slk::Reader *reader);
+  static void Save(const DropDatabaseRes &self, memgraph::slk::Builder *builder);
+  DropDatabaseRes() = default;
+  explicit DropDatabaseRes(Result res) : result(res) {}
+
+  Result result;
+};
+
+using DropDatabaseRpc = rpc::RequestResponse<DropDatabaseReq, DropDatabaseRes>;
+
+}  // namespace memgraph::storage::replication
+
+// SLK serialization declarations
+namespace memgraph::slk {
+
+void Save(const memgraph::storage::replication::CreateDatabaseReq &self, memgraph::slk::Builder *builder);
+
+void Load(memgraph::storage::replication::CreateDatabaseReq *self, memgraph::slk::Reader *reader);
+
+void Save(const memgraph::storage::replication::CreateDatabaseRes &self, memgraph::slk::Builder *builder);
+
+void Load(memgraph::storage::replication::CreateDatabaseRes *self, memgraph::slk::Reader *reader);
+
+void Save(const memgraph::storage::replication::DropDatabaseReq &self, memgraph::slk::Builder *builder);
+
+void Load(memgraph::storage::replication::DropDatabaseReq *self, memgraph::slk::Reader *reader);
+
+void Save(const memgraph::storage::replication::DropDatabaseRes &self, memgraph::slk::Builder *builder);
+
+void Load(memgraph::storage::replication::DropDatabaseRes *self, memgraph::slk::Reader *reader);
+
+}  // namespace memgraph::slk

src/dbms/transaction.hpp

@@ -11,7 +11,10 @@
 
 #pragma once
 
+#include <list>
 #include <memory>
+#include <optional>
+#include "auth/models.hpp"
 #include "storage/v2/config.hpp"
 
 namespace memgraph::dbms {
@@ -20,17 +23,70 @@ struct SystemTransaction {
     enum class Action {
       CREATE_DATABASE,
       DROP_DATABASE,
+      UPDATE_AUTH_DATA,
+      DROP_AUTH_DATA,
+      /**
+       *
+       * CREATE USER user_name [IDENTIFIED BY 'password'];
+       * SET PASSWORD FOR user_name TO 'new_password';
+       * ^ SaveUser
+       *
+       * DROP USER user_name;
+       * ^ Directly on KVStore
+       *
+       * CREATE ROLE role_name;
+       * ^ SaveRole
+       *
+       * DROP ROLE
+       * ^ RemoveRole
+       *
+       * SET ROLE FOR user_name TO role_name;
+       * CLEAR ROLE FOR user_name;
+       * ^ Do stuff then do SaveUser
+       *
+       * GRANT privilege_list TO user_or_role;
+       * DENY AUTH, INDEX TO moderator:
+       * REVOKE AUTH, INDEX TO moderator:
+       * GRANT permission_level ON (LABELS | EDGE_TYPES) label_list TO user_or_role;
+       * REVOKE (LABELS | EDGE_TYPES) label_or_edge_type_list FROM user_or_role
+       * DENY (LABELS | EDGE_TYPES) label_or_edge_type_list TO user_or_role
+       * ^ all of these are EditPermissions <-> SaveUser/Role
+       *
+       * Multi-tenant TODO Doc;
+       * ^ Should all call SaveUser
+       *
+       */
     };
 
     static constexpr struct CreateDatabase {
     } create_database;
     static constexpr struct DropDatabase {
     } drop_database;
+    static constexpr struct UpdateAuthData {
+    } update_auth_data;
+    static constexpr struct DropAuthData {
+    } drop_auth_data;
 
+    enum class AuthData { USER, ROLE };
+
+    // Multi-tenancy
     Delta(CreateDatabase /*tag*/, storage::SalientConfig config)
         : action(Action::CREATE_DATABASE), config(std::move(config)) {}
     Delta(DropDatabase /*tag*/, const utils::UUID &uuid) : action(Action::DROP_DATABASE), uuid(uuid) {}
 
+    // Auth
+    Delta(UpdateAuthData /*tag*/, std::optional<auth::User> user)
+        : action(Action::UPDATE_AUTH_DATA), auth_data{std::move(user), std::nullopt} {}
+    Delta(UpdateAuthData /*tag*/, std::optional<auth::Role> role)
+        : action(Action::UPDATE_AUTH_DATA), auth_data{std::nullopt, std::move(role)} {}
+    Delta(DropAuthData /*tag*/, AuthData type, std::string_view name)
+        : action(Action::DROP_AUTH_DATA),
+          auth_data_key{
+              .type = type,
+              .name = std::string{name},
+          } {}
+
+    // Generic
     Delta(const Delta &) = delete;
     Delta(Delta &&) = delete;
     Delta &operator=(const Delta &) = delete;
@@ -42,8 +98,14 @@ struct SystemTransaction {
           std::destroy_at(&config);
           break;
         case Action::DROP_DATABASE:
+          std::destroy_at(&uuid);
+          break;
+        case Action::UPDATE_AUTH_DATA:
+          std::destroy_at(&auth_data);
+          break;
+        case Action::DROP_AUTH_DATA:
+          std::destroy_at(&auth_data_key);
           break;
-          // Some deltas might have special destructor handling
       }
     }
 
@@ -51,13 +113,20 @@ struct SystemTransaction {
     union {
       storage::SalientConfig config;
       utils::UUID uuid;
+      struct {
+        std::optional<auth::User> user;
+        std::optional<auth::Role> role;
+      } auth_data;
+      struct {
+        AuthData type;
+        std::string name;
+      } auth_data_key;
     };
   };
 
   explicit SystemTransaction(uint64_t timestamp) : system_timestamp(timestamp) {}
 
-  // Currently system transitions support a single delta
-  std::optional<Delta> delta{};
+  std::list<Delta> deltas{};
   uint64_t system_timestamp;
 };
 

src/dbms/utils.hpp

@@ -1,100 +0,0 @@
-// Copyright 2024 Memgraph Ltd.
-//
-// Use of this software is governed by the Business Source License
-// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
-// License, and you may not use this file except in compliance with the Business Source License.
-//
-// As of the Change Date specified in that file, in accordance with
-// the Business Source License, use of this software will be governed
-// by the Apache License, Version 2.0, included in the file
-// licenses/APL.txt.
-#pragma once
-
-#include "dbms/dbms_handler.hpp"
-#include "dbms/replication_handler.hpp"
-#include "replication/include/replication/state.hpp"
-#include "utils/result.hpp"
-
-namespace memgraph::dbms {
-
-inline bool DoReplicaToMainPromotion(dbms::DbmsHandler &dbms_handler) {
-  // STEP 1) bring down all REPLICA servers
-  dbms_handler.ForEach([](DatabaseAccess db_acc) {
-    auto *storage = db_acc->storage();
-    // Remember old epoch + storage timestamp association
-    storage->PrepareForNewEpoch();
-  });
-
-  // STEP 2) Change to MAIN
-  // TODO: restore replication servers if false?
-  if (!dbms_handler.ReplicationState().SetReplicationRoleMain()) {
-    // TODO: Handle recovery on failure???
-    return false;
-  }
-
-  // STEP 3) We are now MAIN, update storage local epoch
-  const auto &epoch =
-      std::get<replication::RoleMainData>(std::as_const(dbms_handler.ReplicationState()).ReplicationData()).epoch_;
-  dbms_handler.ForEach([&](DatabaseAccess db_acc) {
-    auto *storage = db_acc->storage();
-    storage->repl_storage_state_.epoch_ = epoch;
-  });
-
-  return true;
-};
-
-inline bool RegisterAllDatabasesClients(dbms::DbmsHandler &dbms_handler,
-                                        replication::ReplicationClient &instance_client) {
-  if (!allow_mt_repl && dbms_handler.All().size() > 1) {
-    spdlog::warn("Multi-tenant replication is currently not supported!");
-  }
-
-  bool all_clients_good = true;
-
-  // Add database specific clients (NOTE Currently all databases are connected to each replica)
-  dbms_handler.ForEach([&](DatabaseAccess db_acc) {
-    auto *storage = db_acc->storage();
-    if (!allow_mt_repl && storage->name() != kDefaultDB) {
-      return;
-    }
-    // TODO: ATM only IN_MEMORY_TRANSACTIONAL, fix other modes
-    if (storage->storage_mode_ != storage::StorageMode::IN_MEMORY_TRANSACTIONAL) return;
-
-    all_clients_good &= storage->repl_storage_state_.replication_clients_.WithLock(
-        [storage, &instance_client, db_acc = std::move(db_acc)](auto &storage_clients) mutable {  // NOLINT
-          auto client = std::make_unique<storage::ReplicationStorageClient>(instance_client);
-          // All good, start replica client
-          client->Start(storage, std::move(db_acc));
-          // After start the storage <-> replica state should be READY or RECOVERING (if correctly started)
-          // MAYBE_BEHIND isn't a statement of the current state, this is the default value
-          // Failed to start due an error like branching of MAIN and REPLICA
-          if (client->State() == storage::replication::ReplicaState::MAYBE_BEHIND) {
-            return false;
-          }
-          storage_clients.push_back(std::move(client));
-          return true;
-        });
-  });
-
-  return all_clients_good;
-}
-
-inline std::optional<RegisterReplicaError> HandleErrorOnReplicaClient(
-    utils::BasicResult<replication::RegisterReplicaError, replication::ReplicationClient *> &instance_client) {
-  if (instance_client.HasError()) switch (instance_client.GetError()) {
-      case replication::RegisterReplicaError::NOT_MAIN:
-        MG_ASSERT(false, "Only main instance can register a replica!");
-        return {};
-      case replication::RegisterReplicaError::NAME_EXISTS:
-        return dbms::RegisterReplicaError::NAME_EXISTS;
-      case replication::RegisterReplicaError::END_POINT_EXISTS:
-        return dbms::RegisterReplicaError::END_POINT_EXISTS;
-      case replication::RegisterReplicaError::COULD_NOT_BE_PERSISTED:
-        return dbms::RegisterReplicaError::COULD_NOT_BE_PERSISTED;
-      case replication::RegisterReplicaError::SUCCESS:
-        break;
-    }
-  return {};
-}
-
-}  // namespace memgraph::dbms

src/flags/CMakeLists.txt

@@ -1,12 +1,17 @@
-add_library(mg-flags STATIC audit.cpp
-                            bolt.cpp
-                            general.cpp
-                            isolation_level.cpp
-                            log_level.cpp
-                            memory_limit.cpp
-                            run_time_configurable.cpp
-                            storage_mode.cpp
-                            query.cpp
-                            replication.cpp)
-target_include_directories(mg-flags PUBLIC ${CMAKE_SOURCE_DIR}/include)
-target_link_libraries(mg-flags PUBLIC spdlog::spdlog mg-settings mg-utils)
+add_library(mg-flags STATIC
+        audit.cpp
+        bolt.cpp
+        general.cpp
+        isolation_level.cpp
+        log_level.cpp
+        memory_limit.cpp
+        run_time_configurable.cpp
+        storage_mode.cpp
+        query.cpp
+        replication.cpp
+        experimental.cpp
+        experimental.hpp)
+target_include_directories(mg-flags PUBLIC include)
+target_link_libraries(mg-flags
+        PUBLIC spdlog::spdlog mg-settings mg-utils
+        PRIVATE lib::rangev3)

src/flags/all.hpp

@@ -12,6 +12,7 @@
 
 #include "flags/audit.hpp"
 #include "flags/bolt.hpp"
+#include "flags/experimental.hpp"
 #include "flags/general.hpp"
 #include "flags/isolation_level.hpp"
 #include "flags/log_level.hpp"

src/flags/experimental.cpp

@@ -0,0 +1,67 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#include "flags/experimental.hpp"
+#include "range/v3/all.hpp"
+#include "utils/string.hpp"
+
+#include <map>
+#include <string_view>
+
+// Bolt server flags.
+// NOLINTNEXTLINE (cppcoreguidelines-avoid-non-const-global-variables)
+DEFINE_string(experimental_enabled, "",
+              "Experimental features to be used, comma seperated. Options [system-replication]");
+
+using namespace std::string_view_literals;
+
+namespace memgraph::flags {
+
+auto const mapping = std::map{std::pair{"system-replication"sv, Experiments::SYSTEM_REPLICATION}};
+
+auto ExperimentsInstance() -> Experiments & {
+  static auto instance = Experiments{};
+  return instance;
+}
+
+bool AreExperimentsEnabled(Experiments experiments) {
+  using t = std::underlying_type_t<Experiments>;
+
+  auto actual = static_cast<t>(ExperimentsInstance());
+  auto check = static_cast<t>(experiments);
+
+  return (actual & check) == check;
+}
+
+void InitializeExperimental() {
+  namespace rv = ranges::views;
+
+  auto const connonicalize_string = [](auto &&rng) {
+    auto const is_space = [](auto c) { return c == ' '; };
+    auto const to_lower = [](unsigned char c) { return std::tolower(c); };
+
+    return rng | rv::drop_while(is_space) | rv::take_while(std::not_fn(is_space)) | rv::transform(to_lower) |
+           ranges::to<std::string>;
+  };
+
+  auto const mapping_end = mapping.cend();
+  using underlying_type = std::underlying_type_t<Experiments>;
+  auto to_set = underlying_type{};
+  for (auto &&experiment : FLAGS_experimental_enabled | rv::split(',') | rv::transform(connonicalize_string)) {
+    if (auto it = mapping.find(experiment); it != mapping_end) {
+      to_set |= static_cast<underlying_type>(it->second);
+    }
+  }
+
+  ExperimentsInstance() = static_cast<Experiments>(to_set);
+}
+
+}  // namespace memgraph::flags

src/flags/experimental.hpp

@@ -0,0 +1,32 @@
+// Copyright 2024 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include "gflags/gflags.h"
+
+// Short help flag.
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+DECLARE_string(experimental_enabled);
+
+namespace memgraph::flags {
+
+// Each bit is an enabled experiment
+// old experiments can be reused once code cleanup has happened
+enum class Experiments : uint8_t {
+  SYSTEM_REPLICATION = 1 << 0,
+};
+
+bool AreExperimentsEnabled(Experiments experiments);
+
+void InitializeExperimental();
+
+}  // namespace memgraph::flags

src/flags/general.cpp

@@ -195,3 +195,9 @@ DEFINE_HIDDEN_string(organization_name, "", "Organization name.");
 // NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
 DEFINE_string(auth_user_or_role_name_regex, memgraph::glue::kDefaultUserRoleRegex.data(),
               "Set to the regular expression that each user or role name must fulfill.");
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+DEFINE_bool(auth_password_permit_null, true, "Set to false to disable null passwords.");
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+DEFINE_string(auth_password_strength_regex, memgraph::glue::kDefaultPasswordRegex.data(),
+              "The regular expression that should be used to match the entire "
+              "entered password to ensure its strength.");

src/flags/general.hpp

@@ -118,3 +118,7 @@ DECLARE_string(license_key);
 DECLARE_string(organization_name);
 // NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
 DECLARE_string(auth_user_or_role_name_regex);
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+DECLARE_bool(auth_password_permit_null);
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+DECLARE_string(auth_password_strength_regex);

src/flags/replication.cpp

@@ -13,9 +13,17 @@
 
 #ifdef MG_ENTERPRISE
 // NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
-DEFINE_bool(coordinator, false, "Controls whether the instance is a replication coordinator.");
-// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
 DEFINE_uint32(coordinator_server_port, 0, "Port on which coordinator servers will be started.");
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+DEFINE_uint32(raft_server_port, 0, "Port on which raft servers will be started.");
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+DEFINE_uint32(raft_server_id, 0, "Unique ID of the raft server.");
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+DEFINE_uint32(instance_down_timeout_sec, 5, "Time duration after which an instance is considered down.");
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+DEFINE_uint32(instance_health_check_frequency_sec, 1, "The time duration between two health checks/pings.");
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+DEFINE_uint32(instance_get_uuid_frequency_sec, 10, "The time duration between two instance uuid checks.");
 #endif
 
 // NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)

src/flags/replication.hpp

@@ -15,9 +15,17 @@
 
 #ifdef MG_ENTERPRISE
 // NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
-DECLARE_bool(coordinator);
-// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
 DECLARE_uint32(coordinator_server_port);
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+DECLARE_uint32(raft_server_port);
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+DECLARE_uint32(raft_server_id);
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+DECLARE_uint32(instance_down_timeout_sec);
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+DECLARE_uint32(instance_health_check_frequency_sec);
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+DECLARE_uint32(instance_get_uuid_frequency_sec);
 #endif
 
 // NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)

src/glue/ServerT.hpp

@@ -1,4 +1,4 @@
-// Copyright 2023 Memgraph Ltd.
+// Copyright 2024 Memgraph Ltd.
 //
 // Use of this software is governed by the Business Source License
 // included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
@@ -33,7 +33,7 @@ class WritePrioritizedRWLock;
 
 struct Context {
   memgraph::query::InterpreterContext *ic;
-  memgraph::utils::Synchronized<memgraph::auth::Auth, memgraph::utils::WritePrioritizedRWLock> *auth;
+  memgraph::auth::SynchedAuth *auth;
 #if MG_ENTERPRISE
   memgraph::audit::Log *audit_log;
 #endif

src/glue/SessionHL.cpp

@@ -319,8 +319,7 @@ void SessionHL::Configure(const std::map<std::string, memgraph::communication::b
 SessionHL::SessionHL(memgraph::query::InterpreterContext *interpreter_context,
                      memgraph::communication::v2::ServerEndpoint endpoint,
                      memgraph::communication::v2::InputStream *input_stream,
-                     memgraph::communication::v2::OutputStream *output_stream,
-                     memgraph::utils::Synchronized<memgraph::auth::Auth, memgraph::utils::WritePrioritizedRWLock> *auth
+                     memgraph::communication::v2::OutputStream *output_stream, memgraph::auth::SynchedAuth *auth
 #ifdef MG_ENTERPRISE
                      ,
                      memgraph::audit::Log *audit_log

src/glue/SessionHL.hpp

@@ -1,4 +1,4 @@
-// Copyright 2023 Memgraph Ltd.
+// Copyright 2024 Memgraph Ltd.
 //
 // Use of this software is governed by the Business Source License
 // included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
@@ -25,8 +25,7 @@ class SessionHL final : public memgraph::communication::bolt::Session<memgraph::
   SessionHL(memgraph::query::InterpreterContext *interpreter_context,
             memgraph::communication::v2::ServerEndpoint endpoint,
             memgraph::communication::v2::InputStream *input_stream,
-            memgraph::communication::v2::OutputStream *output_stream,
-            memgraph::utils::Synchronized<memgraph::auth::Auth, memgraph::utils::WritePrioritizedRWLock> *auth
+            memgraph::communication::v2::OutputStream *output_stream, memgraph::auth::SynchedAuth *auth
 #ifdef MG_ENTERPRISE
             ,
             memgraph::audit::Log *audit_log
@@ -88,7 +87,7 @@ class SessionHL final : public memgraph::communication::bolt::Session<memgraph::
   memgraph::audit::Log *audit_log_;
   bool in_explicit_db_{false};  //!< If true, the user has defined the database to use via metadata
 #endif
-  memgraph::utils::Synchronized<memgraph::auth::Auth, memgraph::utils::WritePrioritizedRWLock> *auth_;
+  memgraph::auth::SynchedAuth *auth_;
   memgraph::communication::v2::ServerEndpoint endpoint_;
   std::optional<std::string> implicit_db_;
 };

src/glue/auth_checker.cpp

@@ -1,4 +1,4 @@
-// Copyright 2023 Memgraph Ltd.
+// Copyright 2024 Memgraph Ltd.
 //
 // Use of this software is governed by the Business Source License
 // included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
@@ -66,9 +66,7 @@ bool IsUserAuthorizedEdgeType(const memgraph::auth::User &user, const memgraph::
 #endif
 namespace memgraph::glue {
 
-AuthChecker::AuthChecker(
-    memgraph::utils::Synchronized<memgraph::auth::Auth, memgraph::utils::WritePrioritizedRWLock> *auth)
-    : auth_(auth) {}
+AuthChecker::AuthChecker(memgraph::auth::SynchedAuth *auth) : auth_(auth) {}
 
 bool AuthChecker::IsUserAuthorized(const std::optional<std::string> &username,
                                    const std::vector<memgraph::query::AuthQuery::Privilege> &privileges,

src/glue/auth_checker.hpp

@@ -1,4 +1,4 @@
-// Copyright 2023 Memgraph Ltd.
+// Copyright 2024 Memgraph Ltd.
 //
 // Use of this software is governed by the Business Source License
 // included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
@@ -22,8 +22,7 @@ namespace memgraph::glue {
 
 class AuthChecker : public query::AuthChecker {
  public:
-  explicit AuthChecker(
-      memgraph::utils::Synchronized<memgraph::auth::Auth, memgraph::utils::WritePrioritizedRWLock> *auth);
+  explicit AuthChecker(memgraph::auth::SynchedAuth *auth);
 
   bool IsUserAuthorized(const std::optional<std::string> &username,
                         const std::vector<query::AuthQuery::Privilege> &privileges,
@@ -41,7 +40,7 @@ class AuthChecker : public query::AuthChecker {
                                              const std::string &db_name = "");
 
  private:
-  memgraph::utils::Synchronized<memgraph::auth::Auth, memgraph::utils::WritePrioritizedRWLock> *auth_;
+  memgraph::auth::SynchedAuth *auth_;
   mutable memgraph::utils::Synchronized<auth::User, memgraph::utils::SpinLock> user_;  // cached user
 };
 #ifdef MG_ENTERPRISE

src/glue/auth_global.hpp

@@ -1,4 +1,4 @@
-// Copyright 2023 Memgraph Ltd.
+// Copyright 2024 Memgraph Ltd.
 //
 // Use of this software is governed by the Business Source License
 // included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
@@ -13,4 +13,5 @@
 
 namespace memgraph::glue {
 inline constexpr std::string_view kDefaultUserRoleRegex = "[a-zA-Z0-9_.+-@]+";
+static constexpr std::string_view kDefaultPasswordRegex = ".+";
 }  // namespace memgraph::glue

src/glue/auth_handler.cpp

@@ -1,4 +1,4 @@
-// Copyright 2023 Memgraph Ltd.
+// Copyright 2024 Memgraph Ltd.
 //
 // Use of this software is governed by the Business Source License
 // included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
@@ -210,16 +210,25 @@ std::vector<std::vector<memgraph::query::TypedValue>> ShowFineGrainedUserPrivile
   if (!memgraph::license::global_license_checker.IsEnterpriseValidFast()) {
     return {};
   }
-  const auto &label_permissions = user->GetFineGrainedAccessLabelPermissions();
-  const auto &edge_type_permissions = user->GetFineGrainedAccessEdgeTypePermissions();
 
-  auto all_fine_grained_permissions =
-      GetFineGrainedPermissionForPrivilegeForUserOrRole(label_permissions, "LABEL", "USER");
-  auto edge_type_fine_grained_permissions =
-      GetFineGrainedPermissionForPrivilegeForUserOrRole(edge_type_permissions, "EDGE_TYPE", "USER");
+  auto all_fine_grained_permissions = GetFineGrainedPermissionForPrivilegeForUserOrRole(
+      user->GetUserFineGrainedAccessLabelPermissions(), "LABEL", "USER");
+  auto all_role_fine_grained_permissions = GetFineGrainedPermissionForPrivilegeForUserOrRole(
+      user->GetRoleFineGrainedAccessLabelPermissions(), "LABEL", "ROLE");
+  all_fine_grained_permissions.insert(all_fine_grained_permissions.end(),
+                                      std::make_move_iterator(all_role_fine_grained_permissions.begin()),
+                                      std::make_move_iterator(all_role_fine_grained_permissions.end()));
 
-  all_fine_grained_permissions.insert(all_fine_grained_permissions.end(), edge_type_fine_grained_permissions.begin(),
-                                      edge_type_fine_grained_permissions.end());
+  auto edge_type_fine_grained_permissions = GetFineGrainedPermissionForPrivilegeForUserOrRole(
+      user->GetUserFineGrainedAccessEdgeTypePermissions(), "EDGE_TYPE", "USER");
+  auto role_edge_type_fine_grained_permissions = GetFineGrainedPermissionForPrivilegeForUserOrRole(
+      user->GetRoleFineGrainedAccessEdgeTypePermissions(), "EDGE_TYPE", "ROLE");
+  all_fine_grained_permissions.insert(all_fine_grained_permissions.end(),
+                                      std::make_move_iterator(edge_type_fine_grained_permissions.begin()),
+                                      std::make_move_iterator(edge_type_fine_grained_permissions.end()));
+  all_fine_grained_permissions.insert(all_fine_grained_permissions.end(),
+                                      std::make_move_iterator(role_edge_type_fine_grained_permissions.begin()),
+                                      std::make_move_iterator(role_edge_type_fine_grained_permissions.end()));
 
   return ConstructFineGrainedPrivilegesResult(all_fine_grained_permissions);
 }
@@ -233,9 +242,9 @@ std::vector<std::vector<memgraph::query::TypedValue>> ShowFineGrainedRolePrivile
   const auto &edge_type_permissions = role->GetFineGrainedAccessEdgeTypePermissions();
 
   auto all_fine_grained_permissions =
-      GetFineGrainedPermissionForPrivilegeForUserOrRole(label_permissions, "LABEL", "USER");
+      GetFineGrainedPermissionForPrivilegeForUserOrRole(label_permissions, "LABEL", "ROLE");
   auto edge_type_fine_grained_permissions =
-      GetFineGrainedPermissionForPrivilegeForUserOrRole(edge_type_permissions, "EDGE_TYPE", "USER");
+      GetFineGrainedPermissionForPrivilegeForUserOrRole(edge_type_permissions, "EDGE_TYPE", "ROLE");
 
   all_fine_grained_permissions.insert(all_fine_grained_permissions.end(), edge_type_fine_grained_permissions.begin(),
                                       edge_type_fine_grained_permissions.end());
@@ -248,31 +257,15 @@ std::vector<std::vector<memgraph::query::TypedValue>> ShowFineGrainedRolePrivile
 
 namespace memgraph::glue {
 
-AuthQueryHandler::AuthQueryHandler(
-    memgraph::utils::Synchronized<memgraph::auth::Auth, memgraph::utils::WritePrioritizedRWLock> *auth,
-    std::string name_regex_string)
-    : auth_(auth), name_regex_string_(std::move(name_regex_string)), name_regex_(name_regex_string_) {}
+AuthQueryHandler::AuthQueryHandler(memgraph::auth::SynchedAuth *auth) : auth_(auth) {}
 
-bool AuthQueryHandler::CreateUser(const std::string &username, const std::optional<std::string> &password) {
-  if (name_regex_string_ != kDefaultUserRoleRegex) {
-    if (const auto license_check_result =
-            memgraph::license::global_license_checker.IsEnterpriseValid(memgraph::utils::global_settings);
-        license_check_result.HasError()) {
-      throw memgraph::auth::AuthException(
-          "Custom user/role regex is a Memgraph Enterprise feature. Please set the config "
-          "(\"--auth-user-or-role-name-regex\") to its default value (\"{}\") or remove the flag.\n{}",
-          kDefaultUserRoleRegex,
-          memgraph::license::LicenseCheckErrorToString(license_check_result.GetError(), "user/role regex"));
-    }
-  }
-  if (!std::regex_match(username, name_regex_)) {
-    throw query::QueryRuntimeException("Invalid user name.");
-  }
+bool AuthQueryHandler::CreateUser(const std::string &username, const std::optional<std::string> &password,
+                                  system::Transaction *system_tx) {
   try {
     const auto [first_user, user_added] = std::invoke([&, this] {
       auto locked_auth = auth_->Lock();
       const auto first_user = !locked_auth->HasUsers();
-      const auto user_added = locked_auth->AddUser(username, password).has_value();
+      const auto user_added = locked_auth->AddUser(username, password, system_tx).has_value();
       return std::make_pair(first_user, user_added);
     });
 
@@ -291,10 +284,11 @@ bool AuthQueryHandler::CreateUser(const std::string &username, const std::option
             }
           }
 #endif
-      );
+          ,
+          system_tx);
 #ifdef MG_ENTERPRISE
-      GrantDatabaseToUser(auth::kAllDatabases, username);
-      SetMainDatabase(dbms::kDefaultDB, username);
+      GrantDatabaseToUser(auth::kAllDatabases, username, system_tx);
+      SetMainDatabase(dbms::kDefaultDB, username, system_tx);
 #endif
     }
 
@@ -304,73 +298,61 @@ bool AuthQueryHandler::CreateUser(const std::string &username, const std::option
   }
 }
 
-bool AuthQueryHandler::DropUser(const std::string &username) {
-  if (!std::regex_match(username, name_regex_)) {
-    throw memgraph::query::QueryRuntimeException("Invalid user name.");
-  }
+bool AuthQueryHandler::DropUser(const std::string &username, system::Transaction *system_tx) {
   try {
     auto locked_auth = auth_->Lock();
     auto user = locked_auth->GetUser(username);
     if (!user) return false;
-    return locked_auth->RemoveUser(username);
+    return locked_auth->RemoveUser(username, system_tx);
   } catch (const memgraph::auth::AuthException &e) {
     throw memgraph::query::QueryRuntimeException(e.what());
   }
 }
 
-void AuthQueryHandler::SetPassword(const std::string &username, const std::optional<std::string> &password) {
-  if (!std::regex_match(username, name_regex_)) {
-    throw memgraph::query::QueryRuntimeException("Invalid user name.");
-  }
+void AuthQueryHandler::SetPassword(const std::string &username, const std::optional<std::string> &password,
+                                   system::Transaction *system_tx) {
   try {
     auto locked_auth = auth_->Lock();
     auto user = locked_auth->GetUser(username);
     if (!user) {
       throw memgraph::query::QueryRuntimeException("User '{}' doesn't exist.", username);
     }
-    user->UpdatePassword(password);
-    locked_auth->SaveUser(*user);
+    locked_auth->UpdatePassword(*user, password);
+    locked_auth->SaveUser(*user, system_tx);
   } catch (const memgraph::auth::AuthException &e) {
     throw memgraph::query::QueryRuntimeException(e.what());
   }
 }
 
-bool AuthQueryHandler::CreateRole(const std::string &rolename) {
-  if (!std::regex_match(rolename, name_regex_)) {
-    throw memgraph::query::QueryRuntimeException("Invalid role name.");
-  }
+bool AuthQueryHandler::CreateRole(const std::string &rolename, system::Transaction *system_tx) {
   try {
     auto locked_auth = auth_->Lock();
-    return locked_auth->AddRole(rolename).has_value();
+    return locked_auth->AddRole(rolename, system_tx).has_value();
   } catch (const memgraph::auth::AuthException &e) {
     throw memgraph::query::QueryRuntimeException(e.what());
   }
 }
 
 #ifdef MG_ENTERPRISE
-bool AuthQueryHandler::RevokeDatabaseFromUser(const std::string &db, const std::string &username) {
-  if (!std::regex_match(username, name_regex_)) {
-    throw memgraph::query::QueryRuntimeException("Invalid user name.");
-  }
+bool AuthQueryHandler::RevokeDatabaseFromUser(const std::string &db_name, const std::string &username,
+                                              system::Transaction *system_tx) {
   try {
     auto locked_auth = auth_->Lock();
     auto user = locked_auth->GetUser(username);
     if (!user) return false;
-    return locked_auth->RevokeDatabaseFromUser(db, username);
+    return locked_auth->RevokeDatabaseFromUser(db_name, username, system_tx);
   } catch (const memgraph::auth::AuthException &e) {
     throw memgraph::query::QueryRuntimeException(e.what());
   }
 }
 
-bool AuthQueryHandler::GrantDatabaseToUser(const std::string &db, const std::string &username) {
-  if (!std::regex_match(username, name_regex_)) {
-    throw memgraph::query::QueryRuntimeException("Invalid user name.");
-  }
+bool AuthQueryHandler::GrantDatabaseToUser(const std::string &db_name, const std::string &username,
+                                           system::Transaction *system_tx) {
   try {
     auto locked_auth = auth_->Lock();
     auto user = locked_auth->GetUser(username);
     if (!user) return false;
-    return locked_auth->GrantDatabaseToUser(db, username);
+    return locked_auth->GrantDatabaseToUser(db_name, username, system_tx);
   } catch (const memgraph::auth::AuthException &e) {
     throw memgraph::query::QueryRuntimeException(e.what());
   }
@@ -378,9 +360,6 @@ bool AuthQueryHandler::GrantDatabaseToUser(const std::string &db, const std::str
 
 std::vector<std::vector<memgraph::query::TypedValue>> AuthQueryHandler::GetDatabasePrivileges(
     const std::string &username) {
-  if (!std::regex_match(username, name_regex_)) {
-    throw memgraph::query::QueryRuntimeException("Invalid user or role name.");
-  }
   try {
     auto locked_auth = auth_->ReadLock();
     auto user = locked_auth->GetUser(username);
@@ -393,33 +372,28 @@ std::vector<std::vector<memgraph::query::TypedValue>> AuthQueryHandler::GetDatab
   }
 }
 
-bool AuthQueryHandler::SetMainDatabase(std::string_view db, const std::string &username) {
-  if (!std::regex_match(username, name_regex_)) {
-    throw memgraph::query::QueryRuntimeException("Invalid user name.");
-  }
+bool AuthQueryHandler::SetMainDatabase(std::string_view db_name, const std::string &username,
+                                       system::Transaction *system_tx) {
   try {
     auto locked_auth = auth_->Lock();
     auto user = locked_auth->GetUser(username);
     if (!user) return false;
-    return locked_auth->SetMainDatabase(db, username);
+    return locked_auth->SetMainDatabase(db_name, username, system_tx);
   } catch (const memgraph::auth::AuthException &e) {
     throw memgraph::query::QueryRuntimeException(e.what());
   }
 }
 
-void AuthQueryHandler::DeleteDatabase(std::string_view db) {
+void AuthQueryHandler::DeleteDatabase(std::string_view db_name, system::Transaction *system_tx) {
   try {
-    auth_->Lock()->DeleteDatabase(std::string(db));
+    auth_->Lock()->DeleteDatabase(std::string(db_name), system_tx);
   } catch (const memgraph::auth::AuthException &e) {
     throw memgraph::query::QueryRuntimeException(e.what());
   }
 }
 #endif
 
-bool AuthQueryHandler::DropRole(const std::string &rolename) {
-  if (!std::regex_match(rolename, name_regex_)) {
-    throw memgraph::query::QueryRuntimeException("Invalid role name.");
-  }
+bool AuthQueryHandler::DropRole(const std::string &rolename, system::Transaction *system_tx) {
   try {
     auto locked_auth = auth_->Lock();
     auto role = locked_auth->GetRole(rolename);
@@ -428,7 +402,7 @@ bool AuthQueryHandler::DropRole(const std::string &rolename) {
       return false;
     };
 
-    return locked_auth->RemoveRole(rolename);
+    return locked_auth->RemoveRole(rolename, system_tx);
   } catch (const memgraph::auth::AuthException &e) {
     throw memgraph::query::QueryRuntimeException(e.what());
   }
@@ -465,9 +439,6 @@ std::vector<memgraph::query::TypedValue> AuthQueryHandler::GetRolenames() {
 }
 
 std::optional<std::string> AuthQueryHandler::GetRolenameForUser(const std::string &username) {
-  if (!std::regex_match(username, name_regex_)) {
-    throw memgraph::query::QueryRuntimeException("Invalid user name.");
-  }
   try {
     auto locked_auth = auth_->ReadLock();
     auto user = locked_auth->GetUser(username);
@@ -485,9 +456,6 @@ std::optional<std::string> AuthQueryHandler::GetRolenameForUser(const std::strin
 }
 
 std::vector<memgraph::query::TypedValue> AuthQueryHandler::GetUsernamesForRole(const std::string &rolename) {
-  if (!std::regex_match(rolename, name_regex_)) {
-    throw memgraph::query::QueryRuntimeException("Invalid role name.");
-  }
   try {
     auto locked_auth = auth_->ReadLock();
     auto role = locked_auth->GetRole(rolename);
@@ -506,13 +474,8 @@ std::vector<memgraph::query::TypedValue> AuthQueryHandler::GetUsernamesForRole(c
   }
 }
 
-void AuthQueryHandler::SetRole(const std::string &username, const std::string &rolename) {
-  if (!std::regex_match(username, name_regex_)) {
-    throw memgraph::query::QueryRuntimeException("Invalid user name.");
-  }
-  if (!std::regex_match(rolename, name_regex_)) {
-    throw memgraph::query::QueryRuntimeException("Invalid role name.");
-  }
+void AuthQueryHandler::SetRole(const std::string &username, const std::string &rolename,
+                               system::Transaction *system_tx) {
   try {
     auto locked_auth = auth_->Lock();
     auto user = locked_auth->GetUser(username);
@@ -528,16 +491,13 @@ void AuthQueryHandler::SetRole(const std::string &username, const std::string &r
                                                    current_role->rolename());
     }
     user->SetRole(*role);
-    locked_auth->SaveUser(*user);
+    locked_auth->SaveUser(*user, system_tx);
   } catch (const memgraph::auth::AuthException &e) {
     throw memgraph::query::QueryRuntimeException(e.what());
   }
 }
 
-void AuthQueryHandler::ClearRole(const std::string &username) {
-  if (!std::regex_match(username, name_regex_)) {
-    throw memgraph::query::QueryRuntimeException("Invalid user name.");
-  }
+void AuthQueryHandler::ClearRole(const std::string &username, system::Transaction *system_tx) {
   try {
     auto locked_auth = auth_->Lock();
     auto user = locked_auth->GetUser(username);
@@ -545,16 +505,13 @@ void AuthQueryHandler::ClearRole(const std::string &username) {
       throw memgraph::query::QueryRuntimeException("User '{}' doesn't exist .", username);
     }
     user->ClearRole();
-    locked_auth->SaveUser(*user);
+    locked_auth->SaveUser(*user, system_tx);
   } catch (const memgraph::auth::AuthException &e) {
     throw memgraph::query::QueryRuntimeException(e.what());
   }
 }
 
 std::vector<std::vector<memgraph::query::TypedValue>> AuthQueryHandler::GetPrivileges(const std::string &user_or_role) {
-  if (!std::regex_match(user_or_role, name_regex_)) {
-    throw memgraph::query::QueryRuntimeException("Invalid user or role name.");
-  }
   try {
     auto locked_auth = auth_->ReadLock();
     std::vector<std::vector<memgraph::query::TypedValue>> grants;
@@ -602,7 +559,8 @@ void AuthQueryHandler::GrantPrivilege(
     const std::vector<std::unordered_map<memgraph::query::AuthQuery::FineGrainedPrivilege, std::vector<std::string>>>
         &edge_type_privileges
 #endif
-) {
+    ,
+    system::Transaction *system_tx) {
   EditPermissions(
       user_or_role, privileges,
 #ifdef MG_ENTERPRISE
@@ -625,11 +583,13 @@ void AuthQueryHandler::GrantPrivilege(
         }
       }
 #endif
-  );
+      ,
+      system_tx);
 }  // namespace memgraph::glue
 
 void AuthQueryHandler::DenyPrivilege(const std::string &user_or_role,
-                                     const std::vector<memgraph::query::AuthQuery::Privilege> &privileges) {
+                                     const std::vector<memgraph::query::AuthQuery::Privilege> &privileges,
+                                     system::Transaction *system_tx) {
   EditPermissions(
       user_or_role, privileges,
 #ifdef MG_ENTERPRISE
@@ -645,7 +605,8 @@ void AuthQueryHandler::DenyPrivilege(const std::string &user_or_role,
       ,
       [](auto &fine_grained_permissions, const auto &privilege_collection) {}
 #endif
-  );
+      ,
+      system_tx);
 }
 
 void AuthQueryHandler::RevokePrivilege(
@@ -657,7 +618,8 @@ void AuthQueryHandler::RevokePrivilege(
     const std::vector<std::unordered_map<memgraph::query::AuthQuery::FineGrainedPrivilege, std::vector<std::string>>>
         &edge_type_privileges
 #endif
-) {
+    ,
+    system::Transaction *system_tx) {
   EditPermissions(
       user_or_role, privileges,
 #ifdef MG_ENTERPRISE
@@ -679,7 +641,8 @@ void AuthQueryHandler::RevokePrivilege(
         }
       }
 #endif
-  );
+      ,
+      system_tx);
 }  // namespace memgraph::glue
 
 template <class TEditPermissionsFun
@@ -703,10 +666,8 @@ void AuthQueryHandler::EditPermissions(
     ,
     const TEditFineGrainedPermissionsFun &edit_fine_grained_permissions_fun
 #endif
-) {
-  if (!std::regex_match(user_or_role, name_regex_)) {
-    throw memgraph::query::QueryRuntimeException("Invalid user or role name.");
-  }
+    ,
+    system::Transaction *system_tx) {
   try {
     std::vector<memgraph::auth::Permission> permissions;
     permissions.reserve(privileges.size());
@@ -735,7 +696,7 @@ void AuthQueryHandler::EditPermissions(
         }
       }
 #endif
-      locked_auth->SaveUser(*user);
+      locked_auth->SaveUser(*user, system_tx);
     } else {
       for (const auto &permission : permissions) {
         edit_permissions_fun(role->permissions(), permission);
@@ -751,7 +712,7 @@ void AuthQueryHandler::EditPermissions(
         }
       }
 #endif
-      locked_auth->SaveRole(*role);
+      locked_auth->SaveRole(*role, system_tx);
     }
   } catch (const memgraph::auth::AuthException &e) {
     throw memgraph::query::QueryRuntimeException(e.what());

src/glue/auth_handler.hpp

@@ -1,4 +1,4 @@
-// Copyright 2023 Memgraph Ltd.
+// Copyright 2024 Memgraph Ltd.
 //
 // Use of this software is governed by the Business Source License
 // included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
@@ -23,35 +23,36 @@
 namespace memgraph::glue {
 
 class AuthQueryHandler final : public memgraph::query::AuthQueryHandler {
-  memgraph::utils::Synchronized<memgraph::auth::Auth, memgraph::utils::WritePrioritizedRWLock> *auth_;
-  std::string name_regex_string_;
-  std::regex name_regex_;
+  memgraph::auth::SynchedAuth *auth_;
 
  public:
-  AuthQueryHandler(memgraph::utils::Synchronized<memgraph::auth::Auth, memgraph::utils::WritePrioritizedRWLock> *auth,
-                   std::string name_regex_string);
+  explicit AuthQueryHandler(memgraph::auth::SynchedAuth *auth);
 
-  bool CreateUser(const std::string &username, const std::optional<std::string> &password) override;
+  bool CreateUser(const std::string &username, const std::optional<std::string> &password,
+                  system::Transaction *system_tx) override;
 
-  bool DropUser(const std::string &username) override;
+  bool DropUser(const std::string &username, system::Transaction *system_tx) override;
 
-  void SetPassword(const std::string &username, const std::optional<std::string> &password) override;
+  void SetPassword(const std::string &username, const std::optional<std::string> &password,
+                   system::Transaction *system_tx) override;
 
 #ifdef MG_ENTERPRISE
-  bool RevokeDatabaseFromUser(const std::string &db, const std::string &username) override;
+  bool RevokeDatabaseFromUser(const std::string &db_name, const std::string &username,
+                              system::Transaction *system_tx) override;
 
-  bool GrantDatabaseToUser(const std::string &db, const std::string &username) override;
+  bool GrantDatabaseToUser(const std::string &db_name, const std::string &username,
+                           system::Transaction *system_tx) override;
 
   std::vector<std::vector<memgraph::query::TypedValue>> GetDatabasePrivileges(const std::string &username) override;
 
-  bool SetMainDatabase(std::string_view db, const std::string &username) override;
+  bool SetMainDatabase(std::string_view db_name, const std::string &username, system::Transaction *system_tx) override;
 
-  void DeleteDatabase(std::string_view db) override;
+  void DeleteDatabase(std::string_view db_name, system::Transaction *system_tx) override;
 #endif
 
-  bool CreateRole(const std::string &rolename) override;
+  bool CreateRole(const std::string &rolename, system::Transaction *system_tx) override;
 
-  bool DropRole(const std::string &rolename) override;
+  bool DropRole(const std::string &rolename, system::Transaction *system_tx) override;
 
   std::vector<memgraph::query::TypedValue> GetUsernames() override;
 
@@ -61,9 +62,9 @@ class AuthQueryHandler final : public memgraph::query::AuthQueryHandler {
 
   std::vector<memgraph::query::TypedValue> GetUsernamesForRole(const std::string &rolename) override;
 
-  void SetRole(const std::string &username, const std::string &rolename) override;
+  void SetRole(const std::string &username, const std::string &rolename, system::Transaction *system_tx) override;
 
-  void ClearRole(const std::string &username) override;
+  void ClearRole(const std::string &username, system::Transaction *system_tx) override;
 
   std::vector<std::vector<memgraph::query::TypedValue>> GetPrivileges(const std::string &user_or_role) override;
 
@@ -77,10 +78,12 @@ class AuthQueryHandler final : public memgraph::query::AuthQueryHandler {
       const std::vector<std::unordered_map<memgraph::query::AuthQuery::FineGrainedPrivilege, std::vector<std::string>>>
           &edge_type_privileges
 #endif
-      ) override;
+      ,
+      system::Transaction *system_tx) override;
 
   void DenyPrivilege(const std::string &user_or_role,
-                     const std::vector<memgraph::query::AuthQuery::Privilege> &privileges) override;
+                     const std::vector<memgraph::query::AuthQuery::Privilege> &privileges,
+                     system::Transaction *system_tx) override;
 
   void RevokePrivilege(
       const std::string &user_or_role, const std::vector<memgraph::query::AuthQuery::Privilege> &privileges
@@ -91,7 +94,8 @@ class AuthQueryHandler final : public memgraph::query::AuthQueryHandler {
       const std::vector<std::unordered_map<memgraph::query::AuthQuery::FineGrainedPrivilege, std::vector<std::string>>>
           &edge_type_privileges
 #endif
-      ) override;
+      ,
+      system::Transaction *system_tx) override;
 
  private:
   template <class TEditPermissionsFun
@@ -115,6 +119,7 @@ class AuthQueryHandler final : public memgraph::query::AuthQueryHandler {
       ,
       const TEditFineGrainedPermissionsFun &edit_fine_grained_permissions_fun
 #endif
-  );
+      ,
+      system::Transaction *system_tx);
 };
 }  // namespace memgraph::glue

src/io/network/endpoint.cpp

@@ -39,7 +39,7 @@ Endpoint::IpFamily Endpoint::GetIpFamily(const std::string &address) {
 }
 
 std::optional<std::pair<std::string, uint16_t>> Endpoint::ParseSocketOrIpAddress(
-    const std::string &address, const std::optional<uint16_t> default_port = {}) {
+    const std::string &address, const std::optional<uint16_t> default_port) {
   /// expected address format:
   ///   - "ip_address:port_number"
   ///   - "ip_address"