Скачать или смотреть Resolving AWS Lambda SQS Trigger Issues After Queue Recreation

Learn how to handle issues with AWS Lambda SQS triggers not firing after recreating SQS queues. This guide will walk you through effective solutions and best practices for ensuring proper event source mapping.
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This video is based on the question https://stackoverflow.com/q/62391192/ asked by the user 'Ben Gale' ( https://stackoverflow.com/u/529338/ ) and on the answer https://stackoverflow.com/a/62392964/ provided by the user 'stdunbar' ( https://stackoverflow.com/u/2933977/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the Problem: AWS Lambda SQS Trigger Not Firing After Queue Recreation

If you’ve been managing serverless architectures using AWS Lambda and Amazon SQS, you might encounter a situation where the AWS Lambda SQS trigger fails to fire even after recreating the SQS queue. Problems like this can be particularly frustrating, especially after you've invested time and effort into setting up your infrastructure with tools like Terraform.

The Scenario

In this instance, after tearing down your SQS infrastructure and recreating it, the Lambda functions linked to the SQS queues stop processing messages. This anomaly can occur even if the UI indicates that the triggers are properly configured. While the messages accumulate in the queue, your Lambdas remain idle, waiting for actions that won't come until the configuration is corrected.

Diagnosing the Issue

When you recreate an SQS queue, it does not automatically reassociate with existing Lambda functions. This lack of automatic reassociation is a common pitfall because the underlying event source mapping, which links the SQS queue to the Lambda function, becomes invalid even if the ARNs (Amazon Resource Names) appear the same.

Key points to remember:

Event Source Mapping: For each subscription between SQS and Lambda, an event source mapping is created.

Delete and Recreate: Simply deleting and then recreating the SQS queue does not restore the event source mapping.

Solution: Re-establishing the Event Source Mapping

To effectively resolve this issue, you'll need to manually remove the invalid event source mapping and recreate it. Below are the steps to accomplish this:

Step 1: Identify Existing Event Source Mappings

Use the AWS CLI to list the existing event source mappings linked to your Lambda function. Run the following command:

[[See Video to Reveal this Text or Code Snippet]]

Make note of the UUID associated with the invalid mapping.

Step 2: Delete the Existing Mapping

Now, delete the invalid event source mapping using its UUID with the following command:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Recreate the Event Source Mapping

Once the old mapping is deleted, you can recreate it using:

[[See Video to Reveal this Text or Code Snippet]]

Important Consideration

Propagation Delay: Just like there can be a delay in recreating an SQS queue with the same name, there may also be a slight delay in the event source mapping. Be patient, as the changes may take a moment to take effect.

Conclusion

If you find yourself in a situation where AWS Lambda SQS triggers are not firing after queue recreation, remember to check the event source mappings. Properly removing and recreating the mappings will restore the functionality you expect. This process might seem complex, but by following these clear steps, you can resolve this issue efficiently.

Solving AWS challenges can often involve stepping through infrastructure management intricacies, but with a good understanding of event source mappings, you can navigate these situations with confidence.

Now, with your Lambdas back in action, you can focus on building and deploying robust serverless applications efficiently.