Dead Letter Queue example with CDK

DeadLetterQueueStack.ts

import { Queue } from "@aws-cdk/aws-sqs";

import { App, Duration, Stack, StackProps } from "@aws-cdk/core";
import { Runtime, Code, Function } from "@aws-cdk/aws-lambda";
import { SqsEventSource } from "@aws-cdk/aws-lambda-event-sources";

class DeadLetterQueue extends Stack {
  constructor(parent: App, name: string, props?: StackProps) {
    super(parent, name, props);

    // Send things to me if you don't know what to do with it.
    const deadLetterQueue = new Queue(this, "eventSequencingDLQueue", {
      queueName: "dlq.fifo",
      deliveryDelay: Duration.millis(0),
      contentBasedDeduplication: true,
      retentionPeriod: Duration.days(14),
      fifo: true
    });

    // Send messages to me and I'll make sure I hand them to the processor in order.
    const fifoQueue = new Queue(this, "eventSequencingFifoQueue", {
      queueName: "mailbox.fifo",
      deliveryDelay: Duration.millis(0),
      contentBasedDeduplication: true,
      fifo: true,
      visibilityTimeout: Duration.seconds(30),
      deadLetterQueue: {
        maxReceiveCount: 1,
        queue: deadLetterQueue
      }
    });

    // I'm going to send messages.
    const sender = new Function(this, "senderFn", {
      runtime: Runtime.NODEJS_10_X,
      code: Code.asset("./lib/src"),
      handler: "v2/sender/sender.main",
      timeout: Duration.seconds(6),
      memorySize: 256,
      reservedConcurrentExecutions: 1,
      environment: {
        FIFO_QUEUE_URL: fifoQueue.queueUrl
      }
    });

    fifoQueue.grantSendMessages(sender);

    // I'm going to process messages. If I can't process one, I'll put it in the DLQ for you ;-)
    const processor = new Function(this, "processorFn", {
      runtime: Runtime.NODEJS_10_X,
      code: Code.asset("./lib/src"),
      handler: "v2/processor/processor.main",
      timeout: Duration.seconds(6),
      memorySize: 256,
      reservedConcurrentExecutions: 1,
      environment: {
        DLQ_QUEUE_URL: deadLetterQueue.queueUrl
      }
    });

    fifoQueue.grantConsumeMessages(processor);
    deadLetterQueue.grantSendMessages(processor);

    // Put the processor to work. 365 / 24 / 7. No rights for robots yet!
    processor.addEventSource(
      new SqsEventSource(fifoQueue, {
        batchSize: 10
      })
    );
  }
}