Add PDO storage adapter.

.github/workflows/tests.yml

@@ -20,6 +20,11 @@ jobs:
       REDIS_HOST: redis
       # The default Redis port
       REDIS_PORT: 6379
+      # MySQL
+      DB_DATABASE: test
+      DB_USER: root
+      DB_PASSWORD: root
+
     steps:
       - name: Checkout code
         uses: actions/checkout@v2
@@ -40,9 +45,23 @@ jobs:
 
       - name: Install dependencies
         run: composer update --${{ matrix.dependency-version }} --prefer-dist --no-interaction --no-suggest
+
       - name: Start Redis
         uses: supercharge/[email protected]
         with:
           redis-version: ${{ matrix.redis-version }}
-      - name: Execute tests
+
+      - name: Execute tests (PDO with Sqlite)
         run: vendor/bin/phpunit
+
+      - name: Start MySQL
+        run: |
+          sudo /etc/init.d/mysql start
+          mysql -e "CREATE DATABASE IF NOT EXISTS $DB_DATABASE;" -u$DB_USER -p$DB_PASSWORD
+
+      - name: Execute PDO tests with MySQL
+        env:
+          TEST_PDO_DSN: 'mysql:host=localhost;dbname=test'
+          TEST_PDO_USERNAME: 'root'
+          TEST_PDO_PASSWORD: 'root'
+        run: vendor/bin/phpunit tests/Test/Prometheus/PDO

README.md

@@ -102,6 +102,12 @@ $registry = new CollectorRegistry(new APC());
 ```
 (see the `README.APCng.md` file for more details)
 
+Using the PDO storage:
+```php
+$registry = new CollectorRegistry(new \PDO('mysql:host=localhost;dbname=prometheus', 'username', 'password'));
+ or
+$registry = new CollectorRegistry(new \PDO('sqlite::memory:'));
+```
 
 ### Advanced Usage
 

composer.json

@@ -31,6 +31,7 @@
     "suggest": {
         "ext-redis": "Required if using Redis.",
         "ext-apc": "Required if using APCu.",
+        "ext-pdo": "Required if using PDO.",
         "promphp/prometheus_push_gateway_php": "An easy client for using Prometheus PushGateway.",
         "symfony/polyfill-apcu": "Required if you use APCu on PHP8.0+"
     },