Symfony Messenger Pubsub Bundle Laravel Package

Getting Started

Minimal Setup

1. Install the Bundle

   composer require cedricziel/symfony-messenger-pubsub-bundle
   

2. Configure Messenger Transport Add the DSN to your .env:

   MESSENGER_TRANSPORT_DSN=pubsub://your-project-id/your-topic?subscription=your-subscription
   

   Ensure your config/packages/messenger.yaml includes the transport:

   framework:
       messenger:
           transports:
               pubsub: '%env(MESSENGER_TRANSPORT_DSN)%'
   

3. First Use Case: Send a Message Dispatch a message via CLI:

   php bin/console messenger:send MyMessageClass
   

   Verify the message appears in your Pub/Sub topic.

Where to Look First

• Bundle Docs: GitHub README (minimal but clear).
• Symfony Messenger Docs: Official Guide for core concepts.
• Pub/Sub CLI: Use gcloud pubsub topics list to validate topic/subscription names.

Implementation Patterns

Workflows

1. Push vs. Pull

   • Push: Configure HTTP endpoint via routes.xml (auto-generated by the bundle). Useful for real-time processing.

     # config/routes.yaml
     _pubsub_push:
         resource: '@GoogleCloudPubSubMessengerBundle/Resources/config/routes.xml'
     

   • Pull: Default CLI-based polling (configured via MESSENGER_TRANSPORT_DSN). Use for batch processing.

2. Message Handling

   • Symfony Message Classes: Extend Symfony\Component\Messenger\Message or use DTOs.

     class MyMessage implements MessageInterface {
         public string $content;
     }
     

   • Handlers: Register handlers in config/packages/messenger.yaml:

     framework:
         messenger:
             handlers:
                 my_handler:
                     type: MyMessage
                     handler: App\MessageHandler\MyHandler
     

3. Retry Logic Leverage Symfony’s retry strategy for transient failures:

   transports:
       pubsub:
           dsn: '%env(MESSENGER_TRANSPORT_DSN)%'
           retry_strategy:
               max_retries: 3
               delay: 1000
   

Integration Tips

• Google Cloud Auth: Ensure your service account has pubsub.publisher and pubsub.subscriber roles.
• Environment Separation: Use different DSNs for dev/staging/prod (e.g., pubsub://project-dev/topic).
• Monitoring: Integrate with Stackdriver or Cloud Logging for message tracking.

Gotchas and Tips

Pitfalls

1. DSN Format

   • Incorrect Format: pubsub://project/topic?subscription=sub is required. Omitting subscription causes silent failures.
   • Debugging: Use php bin/console debug:messenger to validate transport configuration.

2. Push Endpoint

   • CORS Issues: If using push, ensure your HTTP endpoint accepts POST requests from Google’s IPs (check Pub/Sub docs).
   • Route Conflict: Prefix _pubsub_push routes to avoid clashes with existing routes.

3. Message Size Limits

   • Pub/Sub enforces a 10MB message limit. For larger payloads, use Cloud Storage or compress data.

Debugging

• Logs: Enable debug mode (APP_DEBUG=1) to see transport errors.
• CLI Testing: Simulate messages with:

  php bin/console messenger:consume pubsub -vv
  

• Pub/Sub UI: Verify messages in Google Cloud Console.

Extension Points

1. Custom Middleware Add middleware to transform messages before sending:

   framework:
       messenger:
           transports:
               pubsub:
                   dsn: '%env(MESSENGER_TRANSPORT_DSN)%'
                   middleware:
                       - App\Middleware\PubSubSerializer
   

2. Async Processing Use Symfony’s async workers for high-throughput topics:

   php bin/console messenger:consume pubsub -w --limit=100
   

3. Event Listeners Hook into MESSENGER_MESSAGE_SENT/MESSENGER_MESSAGE_FAILED events for auditing:

   // config/services.yaml
   App\EventListener\PubSubLogger:
       tags:
           - { name: kernel.event_listener, event: MESSENGER_MESSAGE_SENT, method: onMessageSent }