Base Rails Docker Compose File

version: '2'

volumes:
  postgres-data:
    driver: local
  gems:
    driver: local

services:
  db:
    image: postgres:9.5.1
    ports:
      # We'll bind our host's port 5432 to postgres's port 5432, so we can use
      # our database IDEs with it:
      - 5432:5432
    volumes:
      # We'll store the postgres data in the 'postgres-data' volume we defined:
      - postgres-data:/var/lib/postgresql/data
      - ./db/dumps:/db/dumps:ro                # Mount the DB dumps folder
      - ./bin/restoredb:/bin/restoredb:ro      # Mount the 'restoredb' script
    environment:
      POSTGRES_PASSWORD: P4Ssw0rD!

  # The job processor container - we'll use this as a base for the rest of the
  # containers:
  web: &app
    image: ruby:2.2.5
    command: rails server -b 0.0.0.0 -p 3000 -P /tmp/rails.pid
    ports:
      - 3000:3000
    # Specify the directory from where all commands sent to the container will be
    # issued to where the code is mounted:
    working_dir: /usr/src/app

    entrypoint: /usr/src/app/dev-entrypoint

    volumes:
      # Mount our app code directory (".") into our app containers at the
      # "/usr/src/app" folder:
      - .:/usr/src/app

      # Mount the 'gems' volume on the folder that stores bundled gems:
      - gems:/usr/local/bundle

    # Keep the stdin open, so we can attach to our app container's process
    # and do things such as byebug, etc:
    stdin_open: true

    # Enable sending signals (CTRL+C, CTRL+P + CTRL+Q) into the container:
    tty: true

    # Link to our postgres and redis containers, so they can be visible from our
    # app containers:
    links:
      # We'll include a link to the 'db' (postgres) container, making it
      # visible from the container using the 'db' hostname:
      - db

    # Specify environment variables available for our app containers. We'll leave
    # a YML anchor in case we need to override or add more variables if needed on
    # each app container:
    environment: &app_environment

      # We'll overwrite the PATH environment variable to include the 'bin/'
      # directory, for the entrypoint script to find the app's executables:
      PATH: /usr/src/app/bin:/usr/local/bundle/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

      # We'll set the DATABASE_URL environment variable for the app to connect
      # to our postgres container - no need to use a 'config/database.yml' file.
      DATABASE_URL: postgres://postgres:P4Ssw0rD!@db:5432/docker_rails_dev?pool=25&encoding=unicode&schema_search_path=public,partitioning

      # We'll set the RAILS_ENV and RACK_ENV environment variables to
      # 'development', so our app containers will start in 'development' mode
      # on this compose project:
      RAILS_ENV: development
      RACK_ENV: development

    # We'll specify a dotenv file for docker-compose to load more environment
    # variables into our app containers. This dotenv file would normally contain
    # sensitive data (API keys & secrets, etc) which SHOULD NOT be committed into
    # Git.
    # Keep in mind that any changes in this file will require a container restart
    # in order to be available on the app containers:
    env_file:
      - dev.env