Localstack

If you want to use pass4s for SNS/SQS messaging, your usual first step is to set up local development environment. Localstack is a toolkit provided by Amazon to replicate AWS locally. This section provides ready-to-use localstack setup using docker-compose.

Docker compose setup

To launch localstack simply copy the snippet below and save it locally as docker-compose.yml. Once that's done, open terminal, navigate to the place where you saved the file and run docker-compose up. Your setup is ready to go.

version: "3.8"

services:
  localstack:
    container_name: localstack_main
    image: localstack/localstack
    hostname: localhost.localstack.cloud
    ports:
      - "127.0.0.1:4566:4566"            # LocalStack Gateway
      - "127.0.0.1:4510-4559:4510-4559"  # external services port range
    environment:
      - DOCKER_HOST=unix:///var/run/docker.sock
      - SERVICES=sqs,sns
      - EAGER_SERVICE_LOADING=1
      - SKIP_SSL_CERT_DOWNLOAD=1
      - HOSTNAME_EXTERNAL=localhost.localstack.cloud
    volumes:
      - "/tmp/localstack:/var/lib/localstack"
      - "/var/run/docker.sock:/var/run/docker.sock"
  
  setup-resources:
    image: localstack/localstack
    environment:
      - AWS_ACCESS_KEY_ID=test
      - AWS_SECRET_ACCESS_KEY=AWSSECRET
      - AWS_DEFAULT_REGION=eu-west-2
    entrypoint: /bin/sh -c
    command: >
      "
        sleep 15
        alias aws='aws --endpoint-url http://localstack:4566'
        # Executing SNS
        aws sns create-topic --name local_sns
        # Executing SQS
        aws sqs create-queue --queue-name local_queue
        # Subscribing to SNS to SQS
        aws sns subscribe --attributes 'RawMessageDelivery=true' --topic-arn arn:aws:sns:eu-west-2:000000000000:local_sns --protocol sqs --notification-endpoint arn:aws:sqs:eu-west-2:000000000000:local_queue
        aws sqs get-queue-url --queue-name local_queue
        # Create na S3 bucket for large messages
        aws s3 mb s3://large-messages
      "      
    depends_on:
      - localstack

Resources

This setup comes with batteries included, meaning it not only does set up the service, but also some basic resources for you to play with. The provided resources are:

• Topic local_sns to write your messages onto
• Queue local_queue to read messages from
• Subscription between the two, making the messages from local_sns to be pushed to local_queue
• Bucket large-messages in case you want to use s3 proxy

Please notice how for queue creation we use --attributes 'RawMessageDelivery=true'. This is done intentionally, make sure to use this attribute with your production setup to avoid communication issues. We add this because we don't want AWS to try interpreting our JSON message contents. To find out more check out https://docs.aws.amazon.com/sns/latest/dg/sns-large-payload-raw-message-delivery.html