# Version of docker-compose.
version: '3.9'

services:
  # Name of database service.
  talawa_mongodb_service:
    # Name of the created database container.
    container_name: talawa_mongodb

    # Image used for creating the database container.
    # More about it here:- https://hub.docker.com/_/mongo.
    image: mongo

    # Maps port 27017 of host system to port 27017 of container. MongoDB by default
    # runs on port 27017. So, inside the container it runs on port 27017 and
    # after mapping it's accessible on port 27017 on the host system as well.
    ports:
      - 27017:27017

    # Restarts the container automatically.
    restart: always

    # Mounts the data created/stored in container's file system to a host
    # system's volume which is managed by docker. This prevents data deletion
    # if the container is stopped/deleted/rebuilt. To delete the volume as
    # well use 'docker rm -v container_id' command. This is called
    # 'named volume' approach to persisting data with docker.
    volumes:
      - talawa_mongodb:/data/db

  # Name of api service.
  talawa_api_service:
    # Name of the created api(server) container.
    container_name: talawa_api

    # Tells docker-compose the location of Dockerfile.
    build: .

    # Maps port 4000 of host system to port 4000 of container. In
    # development environment talawa-api runs on port 4000. So, inside
    # the container it runs on port 4000 and after mapping it's
    # accessible on port 4000 on the host system as well.
    ports:
      - 4000:4000

    # Restarts the container automatically.
    restart: always

    volumes:
      # Mounts current directory to '/usr/src/app' directory of container.
      # This will keep the files in current directory in sync with container
      # files and any changes made to these files on host system will be reflected
      # inside the container. This is useful for a development environment.
      # This is called the 'bind mount' approach to persisting data with docker.
      - .:/usr/src/app

      # We don't want to sync node_modules folder between the host system and container.
      # It should be updated by rebuilding the image. '.:/usr/src/app' mounts
      # everything present in current host system directory to 'WORKDIR' inside
      # container. But '/usr/src/app/node_modules' maps an empty address to node_modules
      # folder inside the container. Therefore, providing a more specific instruction to docker
      # to ignore node_modules.
      - /usr/src/app/node_modules

    # Makes this service dependent on 'talawa_mongodb_service'. Docker will make sure
    # that 'talawa_mongodb_service' is active/online before running 'talawa_api_service'.
    depends_on:
      - talawa_mongodb_service

volumes:
  talawa_mongodb: {}