docker-compose.yaml

version: '3.9'
services:
  # main backend container
  app:
    # in development process, shuts down the container that may have any issue
    # and let developers to inspect this in detail.
    restart: on-failure:2 # give 2 chances
    build:
      # find dockerfile from root
      context: .
      # in development process, do not bundle code
      # to make it easier to inspect
      target: build
    environment:
      # run as production mode
      - NODE_ENV=production
      # use external DB url,
      # instead of localhost
      - DATABASE_URL=${DATABASE_URL_PROD}
      - JWT_SECRET
      - WORKDIR=/usr/src/app
      # - PORT=80 # default
    ports:
      # default 80, so expose it to safe port
      - 8888:80
    networks:
      - db-connection
    depends_on:
      - db
  db:
    restart: always
    # use default ports
    # you can override this with environment variable
    build:
      context: .
      dockerfile: ./mongodb.Dockerfile
      # /mongodb_replica
    volumes:
      # default to data
      # you can override this volume with environment variable
      - type: volume
        source: ${DB_VOLUME:-data}
        target: /data:db
    # pass environment variable
    environment:
      # passing initial authentication setup
      - MONGO_INITDB_ROOT_USERNAME
      - MONGO_INITDB_ROOT_PASSWORD
      # MUST be same as service name
      - MONGO_REPLICA_HOST=db
      - MONGO_REPLICA_PORT=${DB_PORT:-27017}
    networks:
      - db-connection
    ports:
      - ${DB_PORT:-27017}:27017
volumes:
  # persistent data volume for database
  data:
networks:
  db-connection:
    driver: bridge