Dead letter topics in GCP - Mini Project: Build & Apply

Setting Up Dead Letter Topics in Google Cloud Pub/Sub

📖 Scenario: You are managing a messaging system using Google Cloud Pub/Sub. Sometimes, messages fail to be processed correctly. To handle these failures safely, you want to create a special topic called a dead letter topic where failed messages will be sent for later inspection.

🎯 Goal: Build a Pub/Sub subscription with a dead letter topic configured. This setup ensures that messages that cannot be processed after a certain number of attempts are moved to the dead letter topic automatically.

📋 What You'll Learn

Create a Pub/Sub topic named main-topic

Create a Pub/Sub topic named dead-letter-topic

Create a subscription named main-subscription to main-topic

Configure main-subscription with deadLetterPolicy pointing to dead-letter-topic

Set the maximum delivery attempts to 5

💡 Why This Matters

🌍 Real World

Dead letter topics help keep messaging systems reliable by isolating messages that cannot be processed, so they don't block the flow of good messages.

💼 Career

Understanding dead letter topics is important for cloud engineers and developers working with event-driven architectures and message queues to build fault-tolerant systems.

1

Create the main Pub/Sub topic

Write the gcloud command to create a Pub/Sub topic named main-topic.

GCP

# Your command here

Need a hint?

Use the gcloud pubsub topics create command followed by the topic name.

2

Create the dead letter Pub/Sub topic

Write the gcloud command to create a Pub/Sub topic named dead-letter-topic.

GCP

gcloud pubsub topics create main-topic
# Your command here

Need a hint?

Use the same command as before but with the new topic name.

3

Create the subscription to the main topic

Write the gcloud command to create a subscription named main-subscription to the topic main-topic.

GCP

gcloud pubsub topics create main-topic
gcloud pubsub topics create dead-letter-topic
# Your command here

Need a hint?

Use gcloud pubsub subscriptions create with the subscription name and --topic flag.

4

Configure the subscription with dead letter topic and max delivery attempts

Write the gcloud command to update the subscription main-subscription to set the dead letter topic to dead-letter-topic and set the maximum delivery attempts to 5.

GCP

gcloud pubsub topics create main-topic
gcloud pubsub topics create dead-letter-topic
gcloud pubsub subscriptions create main-subscription --topic=main-topic
# Your command here

Need a hint?

Use gcloud pubsub subscriptions update with --dead-letter-topic and --max-delivery-attempts flags. The dead letter topic must be specified with its full resource name.