How do I implement exponential backoff with SQS redrive policy?

To implement exponential backoff with an SQS redrive policy, we need to create two SQS queues: a main queue and a dead-letter queue (DLQ). The main queue will receive the messages, and if a message fails to be processed after a certain number of attempts, it will be moved to the DLQ. The DLQ will store these failed messages for further inspection or reprocessing.

Here is a detailed explanation followed by the Pulumi program in TypeScript:

1. Create the Dead-Letter Queue (DLQ): This queue will hold the messages that fail to be processed after a certain number of attempts.
2. Create the Main Queue: This is the queue that will receive and process messages. It will be configured with a redrive policy to move failed messages to the DLQ after a specified number of attempts.
3. Configure Redrive Policy: The redrive policy specifies the DLQ and the maximum number of receive attempts before a message is moved to the DLQ.

Here’s the Pulumi program to set this up:

import * as pulumi from "@pulumi/pulumi";
import * as aws from "@pulumi/aws";

// Create the Dead-Letter Queue (DLQ)
const dlq = new aws.sqs.Queue("dlq", {
    messageRetentionSeconds: 1209600, // Retain messages for up to 14 days
});

// Create the Main Queue with a redrive policy
const mainQueue = new aws.sqs.Queue("mainQueue", {
    redrivePolicy: pulumi.output({
        deadLetterTargetArn: dlq.arn,
        maxReceiveCount: 5, // After 5 failed attempts, move the message to the DLQ
    }).apply(JSON.stringify), // Convert the policy to a JSON string
});

// Export the queue URLs
export const mainQueueUrl = mainQueue.id;
export const dlqUrl = dlq.id;

Explanation:

1. Dead-Letter Queue (DLQ):

   • We create a queue named dlq with a retention period of 14 days (messageRetentionSeconds: 1209600).
   • Messages in this queue can be inspected or reprocessed manually if needed.

2. Main Queue:

   • We create a queue named mainQueue with a redrive policy.
   • The redrivePolicy specifies that messages failing to process after 5 attempts (maxReceiveCount: 5) will be moved to the DLQ.
   • We use pulumi.output and apply to convert the redrive policy to a JSON string, as required by AWS.

3. Exporting Queue URLs:

   • We export the URLs of both the main queue and the DLQ so that they can be referenced or used in other parts of your infrastructure.

This setup ensures that messages that cannot be processed successfully after several attempts are moved to a DLQ, allowing for further inspection and manual intervention if necessary.