Lambda Functions Should Have a Dead-Letter Queue Configured Rule
Ensure Lambda functions have a configured dead-letter queue to handle failed executions effectively.
| Rule | Lambda functions should have a dead-letter queue configured |
| Framework | AWS Foundational Security Best Practices |
| Severity | ✔ Medium |
Rule Description
AWS Lambda functions should have a dead-letter queue configured as part of the AWS Foundational Security Best Practices. A dead-letter queue allows the capture and retention of asynchronous event failure information. By using a dead-letter queue, you can troubleshoot and debug the potential issues that may occur in your Lambda function.
Troubleshooting Steps
If the dead-letter queue for a Lambda function is not set up properly or not configured at all, you may encounter issues such as event loss or issues with event processing. Here are the troubleshooting steps to address these problems:
- 1.
Verify Dead-Letter Queue Configuration:
- Firstly, check if the dead-letter queue is enabled for the Lambda function in question.
- Ensure that the correct queue is selected and the queue name or ARN (Amazon Resource Name) is accurate.
- 2.
Check Queue Permissions:
- Verify that the Lambda function has the necessary permissions to write failed events to the dead-letter queue.
- Ensure that the correct queue policy is in place and that the Lambda execution role has the required permissions to send messages to the queue.
- 3.
Validate Queue Settings:
- Ensure that the queue's retention period is set appropriately to retain failed events for a sufficient duration to troubleshoot the issues.
- Confirm that the maximum message size and throughput settings of the dead-letter queue align with your expected Lambda function behavior.
- 4.
Review Lambda Function Configuration:
- Check the Lambda function's configuration to ensure that it is properly configured to send failed events to the dead-letter queue.
- Verify that the function's error handling and retries are aligned with the desired behavior.
- 5.
Monitor CloudWatch Metrics:
- Monitor the relevant CloudWatch metrics for the Lambda function, such as "DeadLetterErrors" or "DeadLetterMessagesSent," to identify any potential issues with the dead-letter queue itself.
Necessary Codes
If the dead-letter queue is not configured for a Lambda function, you can use the AWS Command Line Interface (CLI) to set it up. Here are the necessary codes to configure the dead-letter queue:
- 1.Create a Dead-Letter Queue:
aws sqs create-queue --queue-name MyDeadLetterQueue
- 1.Configure the Dead-Letter Queue for the Lambda Function:
aws lambda update-function-configuration --function-name MyLambdaFunction --dead-letter-config TargetArn=<ARN of MyDeadLetterQueue>
Ensure you replace
MyDeadLetterQueueMyLambdaFunctionStep-by-Step Remediation Guide
To remediate the Lambda function without a dead-letter queue, follow these step-by-step instructions:
- 1.
Create a Dead-Letter Queue:
- Open the AWS Management Console and navigate to the Simple Queue Service (SQS) section.
- Click on "Create New Queue" and provide a suitable name for the dead-letter queue.
- Configure additional settings such as retention period, access control, and message size limits based on your requirements.
- Create the dead-letter queue.
- 2.
Configure the Dead-Letter Queue for the Lambda Function:
- Open the AWS Management Console and navigate to the AWS Lambda service.
- Select the Lambda function that needs to have a dead-letter queue configured.
- Click on "Configure" in the designer view or "Edit" in the function overview page.
- Scroll down to the "Dead letter queue" section and click on "Enable trigger".
- Select the dead-letter queue that you created in step 1 from the drop-down menu or enter the ARN manually.
- 3.
Validate the Dead-Letter Queue Configuration:
- Save the changes to the Lambda function configuration.
- Confirm that the dead-letter queue is set up correctly by verifying the changes within the Lambda function's configuration settings.
With these steps, you have successfully configured a dead-letter queue for the Lambda function, ensuring proper error handling and troubleshooting capabilities in case of event failure.