lambda-dlq-retry

This module providedes the functionality for you to build a Lambda function that retries messages from a Dead Letter Queue (DLQ) for another Lambda. It pulls messages from the SQS DLQ (up to 10 at a time) and passes them back to the original Lambda function in sequence.

lambda-dlq-retry allows you to inspect messages in the DLQ and manually trigger a retry by invoking a retry Lambda.

Usage

To use lambda-dlq-retry, you define a retry Lambda function which passes the event to lambda-dlq-retry. You just need to set the DLQ_QUEUE_NAME and pass the original handler function. Your deployment should

npm install --save lambda-dlq-retry

Add a dlq-handler.js:

const lambdaDlqRetry = require('lambda-dlq-retry')
const handler = require('./handler')

module.exports = {
  retry: lambdaDlqRetry({ handler: handler.original })
}

If you are using the Serverless Framework, the following is an example of the serverless.yml configuration. It creates the SQS queue and sets it as the Dead Letter Queue for the Lambda function. This example has all the relevant Serverless Framework configuration to do that.

functions:
  original:
    handler: handler.original
    onError: !GetAtt dlq.Arn
  retryDlq:
    handler: dlq-handler.retry
    environment:
      DLQ_QUEUE_NAME: ${self:custom.dlqQueueName}

resources:
  Resources:
    dlq:
      Type: AWS::SQS::Queue
      Properties:
        QueueName: ${self:provider.stage}-my-dlq
        MessageRetentionPeriod: 86400 # 1 day

Configuration

Environment variables:

• DLQ_QUEUE_NAME: Required. The name of the queue where failed messages have been sent.
• DLQ_RETRY_MAX_MESSAGES: The maximum number of messages to retrieve and process for a single 'retry' invocation. The default is 10.

You can also pass a logger to lambda-dlq-retry to get debug-level logs on execution. By default, the console object is used.

  retry: lambdaDlqRetry({ handler: handler.original, log: customLogger })

LICENSE

MIT