version: '2'

services:
  sylow:
    build:
      context: .
    volumes:
      # Mounts the project directory on the host to /app inside the container,
      # allowing you to modify the code without having to rebuild the image.
      - .:/app
      # Just specify a path and let the Engine create a volume.
      # Data present in the base image at the specified mount point will be copied
      # over to the new volume upon volume initialization.
      # node_modules from this new volume will be used and not from your local dev env.
      - /app/node_modules/

    # Expose ports [HOST:CONTAINER}
    ports:
      - "4040:4040"

    # Set environment variables from this file
    env_file:
      - .env

    # Overwrite any env var defined in .env file (if required)
    environment:
      - MONGO_HOST=mongodb://mongo/sylow-development
      - DEBUG=sylow:*

    # Link to containers in another service.
    # Links also express dependency between services in the same way as depends_on,
    # so they determine the order of service startup.
    links:
      - mongo
  mongo:
    image: "mongo:3.4.2"
    ports:
      - "27017:27017"

version: '2'

services:
  sylow:
    build:
      context: .
    volumes:
      # Mounts the project directory on the host to /app inside the container,
      # allowing you to modify the code without having to rebuild the image.
      - .:/app
      # Just specify a path and let the Engine create a volume.
      # Data present in the base image at the specified mount point will be copied
      # over to the new volume upon volume initialization.
      # node_modules from this new volume will be used and not from your local dev env.
      - /app/node_modules/

    # Expose ports [HOST:CONTAINER}
    ports:
      - "4040:4040"

    # Set environment variables from this file
    env_file:
      - .env

    # Overwrite any env var defined in .env file (if required)
    environment:
      - MONGO_HOST=mongodb://mongo/sylow-development
      - DEBUG=sylow:*

    # Link to containers in another service.
    # Links also express dependency between services in the same way as depends_on,
    # so they determine the order of service startup.
    links:
      - mongo
  mongo:
    image: "mongo:3.4.2"
    ports:
      - "27018:27018"

Change mongodb port in for docker
Change mongodb port in for docker
