diff --git a/.docker/ci/Dockerfile b/.docker/ci/Dockerfile
index f2287c0..746b6a3 100644
--- a/.docker/ci/Dockerfile
+++ b/.docker/ci/Dockerfile
@@ -14,7 +14,7 @@ COPY --from=node /usr/local/lib/node_modules /usr/local/lib/node_modules
 RUN ln -s /usr/local/lib/node_modules/npm/bin/npm-cli.js /usr/local/bin/npm \
     && ln -s /usr/local/lib/node_modules/npm/bin/npx-cli.js /usr/local/bin/npx \
     && apt-get update \
-    && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends postgresql-client \
+    && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends default-mysql-client-core postgresql-client \
     && rm -rf /var/lib/apt/lists/* \
     && locale-gen en_AU.UTF-8 \
     && git init /opt/moodle-plugin-ci \
diff --git a/.gitea/workflows/ci.yml b/.gitea/workflows/ci.yml
index a9e28fe..4a1c51b 100644
--- a/.gitea/workflows/ci.yml
+++ b/.gitea/workflows/ci.yml
@@ -13,19 +13,30 @@ permissions:
 
 jobs:
   test:
+    name: Test (${{ matrix.database }})
     runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - database: postgresql
+            profile: ""
+            service: ci
+          - database: mysql
+            profile: --profile mysql
+            service: ci-mysql
     env:
-      COMPOSE_PROJECT_NAME: local_webhooks_${{ gitea.run_id }}_${{ gitea.run_attempt }}
+      COMPOSE_PROJECT_NAME: local_webhooks_${{ gitea.run_id }}_${{ gitea.run_attempt }}_${{ matrix.database }}
     steps:
       - name: Check out repository
         uses: https://github.com/actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
 
       - name: Build test image
-        run: docker compose build --pull ci
+        run: docker compose ${{ matrix.profile }} build --pull ${{ matrix.service }}
 
       - name: Test plugin
-        run: docker compose up --abort-on-container-exit --exit-code-from ci
+        run: docker compose ${{ matrix.profile }} up --abort-on-container-exit --exit-code-from ${{ matrix.service }} ${{ matrix.service }}
 
       - name: Clean up
         if: always()
-        run: docker compose down --volumes --remove-orphans
+        run: docker compose ${{ matrix.profile }} down --volumes --remove-orphans --rmi local
diff --git a/README.md b/README.md
index 48cae76..a5278b6 100644
--- a/README.md
+++ b/README.md
@@ -10,15 +10,26 @@ The `develop` branch is unreleased modernization work toward `6.0.0` and is not
 
 ## Current CI baseline
 
-Gitea Actions currently tests only Moodle `5.2.2` on PHP `8.4` with PostgreSQL `16`. This is a development baseline, not the final support matrix.
+Gitea Actions currently tests Moodle `5.2.2` on PHP `8.4` with PostgreSQL `16` and MySQL `8.4`. This is a development baseline, not the final support matrix.
 
 Run the same checks from the repository root with Docker:
 
+PostgreSQL:
+
 ```bash
-export COMPOSE_PROJECT_NAME=local_webhooks_local
+export COMPOSE_PROJECT_NAME=local_webhooks_local_postgresql
 docker compose build --pull ci
-docker compose up --abort-on-container-exit --exit-code-from ci
-docker compose down --volumes --remove-orphans
+docker compose up --abort-on-container-exit --exit-code-from ci ci
+docker compose down --volumes --remove-orphans --rmi local
+```
+
+MySQL:
+
+```bash
+export COMPOSE_PROJECT_NAME=local_webhooks_local_mysql
+docker compose --profile mysql build --pull ci-mysql
+docker compose --profile mysql up --abort-on-container-exit --exit-code-from ci-mysql ci-mysql
+docker compose --profile mysql down --volumes --remove-orphans --rmi local
 ```
 
 ## License
diff --git a/compose.yaml b/compose.yaml
index 7d2f1bd..52f8fda 100644
--- a/compose.yaml
+++ b/compose.yaml
@@ -1,3 +1,25 @@
+x-ci: &ci
+  build:
+    context: .
+    dockerfile: .docker/ci/Dockerfile
+  command:
+    - /bin/bash
+    - -lc
+    - |
+      set -euo pipefail
+      php --version
+      composer --version
+      node --version
+      moodle-plugin-ci --version
+      moodle-plugin-ci install --plugin /plugin --branch v5.2.2 --db-host "$$DB_HOST"
+      test "$$(git -C /workspace/moodle rev-parse HEAD)" = "acfa383c13dd46c83ca82894a8e95fac273fda33"
+      moodle-plugin-ci phplint
+      moodle-plugin-ci phpcs --max-warnings 0
+      moodle-plugin-ci phpdoc --max-warnings 0
+      moodle-plugin-ci validate
+      moodle-plugin-ci savepoints
+      moodle-plugin-ci phpunit --fail-on-warning
+
 services:
   postgres:
     image: postgres:16.13-alpine3.22@sha256:caf536ebd910e85473a9f5e2fd1aea360c965c4a911c8555ac1f61b2102006cb
@@ -12,10 +34,22 @@ services:
     tmpfs:
       - /var/lib/postgresql/data
 
+  mysql:
+    profiles:
+      - mysql
+    image: mysql:8.4.11@sha256:b3b90af2a6552ae30c266fdb7d5dd55f3afb72404bb78d37fe8a23eb857fd3fb
+    environment:
+      MYSQL_ROOT_PASSWORD: moodle_ci
+    healthcheck:
+      test: ["CMD-SHELL", "mysql --protocol=TCP --host=127.0.0.1 --user=root --password=$$MYSQL_ROOT_PASSWORD --execute='SELECT 1' --silent"]
+      interval: 2s
+      timeout: 5s
+      retries: 30
+    tmpfs:
+      - /var/lib/mysql
+
   ci:
-    build:
-      context: .
-      dockerfile: .docker/ci/Dockerfile
+    <<: *ci
     depends_on:
       postgres:
         condition: service_healthy
@@ -25,20 +59,18 @@ services:
       DB_USER: postgres
       MOODLE_BRANCH: v5.2.2
       NPM_CONFIG_FETCH_RETRIES: 5
-    command:
-      - /bin/bash
-      - -lc
-      - |
-        set -euo pipefail
-        php --version
-        composer --version
-        node --version
-        moodle-plugin-ci --version
-        moodle-plugin-ci install --plugin /plugin --branch v5.2.2 --db-host postgres
-        test "$$(git -C /workspace/moodle rev-parse HEAD)" = "acfa383c13dd46c83ca82894a8e95fac273fda33"
-        moodle-plugin-ci phplint
-        moodle-plugin-ci phpcs --max-warnings 0
-        moodle-plugin-ci phpdoc --max-warnings 0
-        moodle-plugin-ci validate
-        moodle-plugin-ci savepoints
-        moodle-plugin-ci phpunit --fail-on-warning
+
+  ci-mysql:
+    <<: *ci
+    profiles:
+      - mysql
+    depends_on:
+      mysql:
+        condition: service_healthy
+    environment:
+      DB: mysqli
+      DB_HOST: mysql
+      DB_PASS: moodle_ci
+      DB_USER: root
+      MOODLE_BRANCH: v5.2.2
+      NPM_CONFIG_FETCH_RETRIES: 5