docker: Update to latest stable MySQL, PostgreSQL

MySQL 9.7 changed the default gtid_mode from OFF to ON (since 9.5). When
the MySQL Docker container initialises, the init scripts run with
GTID=ON, leaving non-empty GTID_EXECUTED in the binary log even though
the final server starts with --gtid-mode=OFF.

This causes two problems:

1. mysqldump always includes SET @@GLOBAL.GTID_PURGED when cloning
   test databases for parallel tests. Restoring this requires
   SYSTEM_VARIABLES_ADMIN, which was not granted.

2. mysqldump requires PROCESS to dump tablespace information. While
   PROCESS was being granted, SYSTEM_VARIABLES_ADMIN was missing
   from the grants, causing clone failures (exit code 5) for Django
   6.0's stricter parallel test runner.

Fix both issues by:

- Running RESET BINARY LOGS AND GTIDS before granting privileges,
  which clears the GTID state left by the init phase so mysqldump
  no longer emits GTID_PURGED statements.

- Adding SYSTEM_VARIABLES_ADMIN to the privilege grants so that if
  any GTID state is present (e.g. in future MySQL versions), the
  restore can set GTID_PURGED.

Signed-off-by: Stephen Finucane <stephen@that.guru>
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: stephenfin

.github/workflows/ci.yaml

@@ -47,7 +47,7 @@ jobs:
       MYSQL_ROOT_PASSWORD: root-${{ github.run_id }}
     services:
       postgres:
-        image: postgres:17
+        image: postgres:18
         env:
           POSTGRES_DB: ${{ env.DATABASE_NAME }}
           POSTGRES_PASSWORD: ${{ env.DATABASE_PASSWORD }}
@@ -60,7 +60,7 @@ jobs:
           --health-timeout 5s
           --health-retries 5
       mysql:
-        image: mysql:8.4
+        image: mysql:9.7
         env:
           MYSQL_DATABASE: ${{ env.DATABASE_NAME }}
           MYSQL_USER: ${{ env.DATABASE_USER }}
@@ -73,6 +73,8 @@ jobs:
           --health-interval 10s
           --health-timeout 5s
           --health-retries 5
+          --gtid-mode=OFF
+          --enforce-gtid-consistency=OFF
     steps:
       - name: Checkout source code
         uses: actions/checkout@v6
@@ -98,8 +100,11 @@ jobs:
       - name: Modify database user permissions (mysql)
         if: ${{ matrix.db == 'mysql' }}
         run: |
-          mysql -h 127.0.0.1 -e "GRANT ALL ON \`test\\_${DATABASE_NAME}%\`.* to '${DATABASE_USER}'@'%';" \
-              -uroot -p${MYSQL_ROOT_PASSWORD}
+          mysql -h 127.0.0.1 -uroot -p${MYSQL_ROOT_PASSWORD} -e \
+              "RESET BINARY LOGS AND GTIDS;
+               GRANT ALL ON \`test\\_${DATABASE_NAME}%\`.* TO '${DATABASE_USER}'@'%';
+               GRANT PROCESS, SESSION_VARIABLES_ADMIN, SYSTEM_VARIABLES_ADMIN ON *.* TO '${DATABASE_USER}'@'%';
+               FLUSH PRIVILEGES;"
       - name: Run unit tests (via tox)
         run: tox
   docs:
@@ -164,8 +169,12 @@ jobs:
       - name: Modify database user permissions (mysql)
         if: ${{ matrix.db == 'mysql' }}
         run: |
-          docker compose exec -T -- db \
-              sh -c "exec mysql -uroot -p\"\${MYSQL_ROOT_PASSWORD}\" -e \"GRANT ALL ON \\\`test\\_\${MYSQL_DATABASE}%\\\`.* to '\${MYSQL_USER}'@'%'; FLUSH PRIVILEGES;\""
+          docker compose exec -T -- db sh -c \
+              "exec mysql -uroot -p\"\${MYSQL_ROOT_PASSWORD}\" -e \
+              \"RESET BINARY LOGS AND GTIDS;
+               GRANT ALL ON \\\`test\\_\${MYSQL_DATABASE}%\\\`.* TO '\${MYSQL_USER}'@'%';
+               GRANT PROCESS, SESSION_VARIABLES_ADMIN, SYSTEM_VARIABLES_ADMIN ON *.* TO '\${MYSQL_USER}'@'%';
+               FLUSH PRIVILEGES;\""
       - name: Run unittest
         run: docker compose run -T --rm web tox
       - name: Test normal startup

docker-compose-pg.yml

@@ -1,9 +1,9 @@
 ---
 services:
   db:
-    image: postgres:17
+    image: postgres:18
     volumes:
-      - ./tools/docker/db/postdata:/var/lib/postgresql/data
+      - ./tools/docker/db/postdata:/var/lib/postgresql
     environment:
       - POSTGRES_DB=patchwork
       - POSTGRES_USER=patchwork

docker-compose.yml

@@ -1,7 +1,8 @@
 ---
 services:
   db:
-    image: mysql:latest
+    image: mysql:9.7
+    command: --gtid-mode=OFF --enforce-gtid-consistency=OFF
     volumes:
       - ./tools/docker/db/data:/var/lib/mysql
     environment: