Pub/Sub Guide

# Create topic gcloud pubsub topics create my-topic # Create pull subscription gcloud pubsub subscriptions create my-sub \ --topic=my-topic \ --ack-deadline=60 \ --message-retention-duration=7d \ --expiration-period=never # Create push subscription gcloud pubsub subscriptions create my-push-sub \ --topic=my-topic \ --push-endpoint=https://my-service.run.app/push \ --push-auth-service-account=push-sa@my-project.iam.gserviceaccount.com \ --ack-deadline=30 # List topics and subscriptions gcloud pubsub topics list gcloud pubsub subscriptions list # Delete gcloud pubsub topics delete my-topic gcloud pubsub subscriptions delete my-sub

# Publish single message gcloud pubsub topics publish my-topic \ --message='{"event":"user_signup","user_id":"123"}' \ --attribute=source=web,version=2 # Publish multiple messages from file gcloud pubsub topics publish my-topic \ --message="$(cat payload.json)" # Python SDK example # from google.cloud import pubsub_v1 # publisher = pubsub_v1.PublisherClient() # topic_path = publisher.topic_path("my-project", "my-topic") # future = publisher.publish( # topic_path, # b'{"event": "order_placed"}', # ordering_key="customer-123" # ) # print(f"Published: {future.result()}")

# Pull messages (synchronous) gcloud pubsub subscriptions pull my-sub --limit=10 --auto-ack # Pull without auto-ack (then manually ack) gcloud pubsub subscriptions pull my-sub --limit=5 # Acknowledge message gcloud pubsub subscriptions ack my-sub \ --ack-ids=ACK_ID_1,ACK_ID_2 # Seek subscription to timestamp (replay messages) gcloud pubsub subscriptions seek my-sub \ --time="2024-01-15T10:00:00Z" # Seek to snapshot gcloud pubsub snapshots create my-snapshot --subscription=my-sub gcloud pubsub subscriptions seek my-sub --snapshot=my-snapshot

# Create dead letter topic gcloud pubsub topics create my-topic-dead-letter # Create subscription with dead letter policy gcloud pubsub subscriptions create my-sub \ --topic=my-topic \ --dead-letter-topic=my-topic-dead-letter \ --max-delivery-attempts=5 # Grant Pub/Sub SA permission to forward to DLT PROJECT_NUMBER=$(gcloud projects describe my-project --format='value(projectNumber)') gcloud pubsub topics add-iam-policy-binding my-topic-dead-letter \ --member="serviceAccount:service-${PROJECT_NUMBER}@gcp-sa-pubsub.iam.gserviceaccount.com" \ --role="roles/pubsub.publisher" gcloud pubsub subscriptions add-iam-policy-binding my-sub \ --member="serviceAccount:service-${PROJECT_NUMBER}@gcp-sa-pubsub.iam.gserviceaccount.com" \ --role="roles/pubsub.subscriber"

# Enable message ordering on subscription gcloud pubsub subscriptions create ordered-sub \ --topic=my-topic \ --enable-message-ordering # Publish with ordering key (messages with same key are ordered) gcloud pubsub topics publish my-topic \ --message="step-1" \ --ordering-key="user-456" gcloud pubsub topics publish my-topic \ --message="step-2" \ --ordering-key="user-456" # Note: ordering requires publishing to the same region # Use --enable-exactly-once-delivery for stronger guarantees