Google Pub/Sub Subscription expired error encountered when attempting to pull messages.

What is Google Pub/Sub Subscription expired error encountered when attempting to pull messages.

Understanding Google Pub/Sub

Google Cloud Pub/Sub is a messaging service designed to provide reliable, many-to-many, asynchronous messaging between applications. It decouples senders and receivers, allowing for scalable and flexible communication. Pub/Sub is commonly used for event-driven architectures, streaming analytics, and integrating microservices.

Identifying the Subscription Expired Symptom

When working with Google Pub/Sub, you might encounter an error message indicating that a subscription has expired. This typically occurs when attempting to pull messages from a subscription that has been inactive for a period longer than its expiration policy allows.

Common Error Message

The error message might look something like this:

SUBSCRIPTION_EXPIRED: The subscription has expired due to inactivity.

Explaining the Subscription Expired Issue

In Google Pub/Sub, subscriptions can be configured with an expiration policy. By default, a subscription expires if it is inactive for 31 days. Inactivity is defined as the absence of any pull or push requests for messages. This feature helps manage resources by automatically cleaning up unused subscriptions.

Why Subscriptions Expire

Subscriptions expire to prevent resource wastage and to ensure that only actively used subscriptions consume system resources. This is particularly important in large-scale systems where managing numerous subscriptions can become complex.

Steps to Fix the Subscription Expired Issue

To resolve the subscription expired issue, you can either recreate the subscription or adjust the expiration policy to prevent future expirations. Here are the steps to do so:

Recreate the Subscription

Delete the expired subscription using the Google Cloud Console or the gcloud command-line tool:

gcloud pubsub subscriptions delete [SUBSCRIPTION_NAME]

Create a new subscription with the desired configuration:

gcloud pubsub subscriptions create [NEW_SUBSCRIPTION_NAME] --topic=[TOPIC_NAME]

Adjust the Expiration Policy

To prevent future expirations, adjust the expiration policy of the subscription:

gcloud pubsub subscriptions update [SUBSCRIPTION_NAME] --expiration-period=[DURATION]

Set the [DURATION] to a value that suits your needs, such as never to disable expiration or a specific duration like 60d for 60 days.

Additional Resources

For more information on managing subscriptions and expiration policies, refer to the following resources:

Subscription Expiration Documentation Administering Pub/Sub gcloud pubsub subscriptions command reference