Subscribe to queues with dead-letter queue

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Messages not processed successfully by the primary subscriber function will be sent to the dead-letter queue after the retry limit is reached.

sst.config.ts

// create dead letter queue
const dlq = new sst.aws.Queue("DeadLetterQueue");
dlq.subscribe("subscriber.dlq");

// create main queue
const queue = new sst.aws.Queue("MyQueue", {
  dlq: dlq.arn,
});
queue.subscribe("subscriber.main");

const app = new sst.aws.Function("MyApp", {
  handler: "publisher.handler",
  link: [queue],
  url: true,
});

subscriber.ts

import type { SQSEvent, SQSHandler } from "aws-lambda";

export const main = async (event) => {
  console.log(event);
  throw new Error("Manual error");
};

export const dlq: SQSHandler = async (event: SQSEvent) => {
  console.log(event);
  return;
};

publisher.ts

import { Resource } from "sst";
import { SQSClient, SendMessageCommand } from "@aws-sdk/client-sqs";
const client = new SQSClient();

export const handler = async (event) => {
  // send a message
  await client.send(
    new SendMessageCommand({
      QueueUrl: Resource.MyQueue.url,
      MessageBody: "Hello from the subscriber",
    })
  );

  return {
    statusCode: 200,
    body: JSON.stringify({ status: "sent" }, null, 2),
  };
};

View the full example.