Localstack

LocalStack is a cloud service emulator that runs in a single container on your laptop or in your CI environment. With LocalStack, you can run your AWS applications or Lambdas entirely on your local machine without connecting to a remote cloud provider! Read the Docs.
Localstack provides us with a dockerfile and a docker-compose to run locally. let’s set it up.
In a docker-copmose.yml let’s add these 2 containers:

• localstack

• dynamodb-admin

version: '3.9'

services:
  dynamodb:
    image: aaronshaf/dynamodb-admin
    ports:
      - "8001:8001"
    environment:
      - DYNAMO_ENDPOINT=http://localstack:4566
    networks:
      - localstack-net

  localstack:
    container_name: "${LOCALSTACK_DOCKER_NAME-localstack_main}"
    image: localstack/localstack:1.2.0
    ports:
      - "127.0.0.1:4566:4566"            # LocalStack Gateway
      - "127.0.0.1:4510-4559:4510-4559"  # external services port range
      - "127.0.0.1:53:53"                # DNS config (only required for Pro)
      - "127.0.0.1:53:53/udp"            # DNS config (only required for Pro)
      - "127.0.0.1:443:443"              # LocalStack HTTPS Gateway (only required for Pro)
    environment:
      - DEBUG=${DEBUG-}
      - PERSISTENCE=${PERSISTENCE-}
      - LAMBDA_EXECUTOR=local
      - LOCALSTACK_API_KEY=${LOCALSTACK_API_KEY-}  # only required for Pro
      - DOCKER_HOST=unix:///var/run/docker.sock
    volumes:
      - "${LOCALSTACK_VOLUME_DIR:-./volume}:/var/lib/localstack"
      - "/var/run/docker.sock:/var/run/docker.sock"
    networks:
      - localstack-net

networks:
  localstack-net:
    name: localstack-net

Now Let’s spin our containers up:

docker-compose up -d

To view the logs you can run this of localstack you can run this:

docker logs -f --tail 500 `docker ps |grep localstack |awk '{print $1}'`

(or just do docker ps grep the id, and run docker logs -f --tail 500 <id>)

serverless framework integration with localstack

One last part before we can deploy our application locally is to configure our up to work with local stack.
To achieve that we will add a section to the templated serverless.yml file. We will use this serverless plugin

• serverless-localstack.
  

• serverless-python-requirements.
  In your terminal run this command

npm install --save serverless@2.72.3
npm install --save-dev serverless-localstack@1.0.1
npm install --save-dev serverless-python-requirements@5.4.0

You can see the added plugin in package.json.

Now, let’s add it to the serverless.yml file:
Add in the uppermost hierarchy:

plugins:
  - serverless-python-requirements
  - serverless-localstack

Let’s minimize the deployed package size by adding this in serverless.yml (directly, not in another section)

package:
  exclude:
    - './**'
  include:
    - './handler.py'

And again, add in the uppermost hierarchy::

custom:
  localstack:
    stages:
      # list of stages for which the plugin should be enabled
      - local
    host: http://localhost  # optional - LocalStack host to connect to
    edgePort: 4566  # optional - LocalStack edge port to connect to
    autostart: true  # optional - Start LocalStack in Docker on Serverless deploy
    networks: #optional - attaches the list of networks to the localstack docker container after startup
      - host
      - overlay
      - localstack-net
    lambda:
      # Enable this flag to improve performance
      mountCode: false  # specify either "true", or a relative path to the root Lambda mount path
    docker:
      # Enable this flag to run "docker ..." commands as sudo
      sudo: False
  pythonRequirements:
    fileName: requirements.txt
    dockerizePip: false