Software development Docker Ruby on Rails

Ruby on Rails

Setup

My current Ruby setup runs these services:

app: A Ruby development server, with a local source directory added as bind mount. It runs a Puma web server, and a Sidekiq server for background jobs, such as sending emails.
db: A Postgres server, with its database stored on a Docker volume.
redis: A Redis server.
pgadmin: A PgAdmin server, to manage the Postgres database(s).
mailcatcher: A mail host to inspect emails that are sent in the current session.
chrome: A Chrome server to run headless Selenium tests.

Configuration remarks:

The local directory is added via a bind mount, but nothing has been done yet to test how files uploaded to the server are handled.

The app server will be built within the container. My local machine has no Ruby or Yarn installed.
This creates a problem with providing an updated Gemfile.lock or yarn.lock, or having up to date node_modules. My workaround is to run a bash shell in the container, with a bind of my local directory, to install new a Gem or NPM package.
Some of the Gems come from private GitHub repositories. It is therefore necessary to pass an access token, using Docker secrets, and to supply them to bundle as environment variable.
It appears that the Ruby server does not do a lookup of localhost, and so the setting extra_hosts: localhost:host-gateway in docker-compose.yml has no effect. Instead, we add host: redis to config/redis.yml.

Example files

.env

# Postgres database
POSTGRES_USER=myusername
POSTGRES_PASSWORD=mysecretpassword
POSTGRES_DB=mydatabase

# Access to the PgAdmin server (then connect to the database)
PGADMIN_DEFAULT_EMAIL=user@domain.com
PGADMIN_DEFAULT_PASSWORD=password

# Available ports to connect to services inside the project
APP_PORT=3000
POSTGRES_PORT=35432
PGADMIN_PORT=8080
REDIS_PORT=36379
MAILCATCHER_PORT=31080

# Secrets to download private repositories from GitHub
GITHUB_TOKEN=...personal access token...
GITHUB_USER=username

RUBY_DEBUG_PORT=1234

Procfile.dev

# Run the web app with the debugger enabled (1)
web: RUBY_DEBUG_OPEN=true bin/rails s -p ${APP_PORT} -b 0.0.0.0
# js: yarn build
css: yarn build:css --watch
worker: bundle exec sidekiq

1	In VS Code, with the Dev Containers extension, it is possible to connect to the debugger. I have not found a way in RubyMine yet.

docker-compose.yml

version: '3.9'

services:
  db:
    image: postgres:13.4
    environment:
      POSTGRES_USER: ${POSTGRES_USER}
      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}
      POSTGRES_DB: ${POSTGRES_DB}
    ports:
      - "${POSTGRES_PORT}:5432"
    volumes:
      - postgres-data:/var/lib/postgresql/data

  redis:
    image: redis
    ports:
      - "${REDIS_PORT}:6379"

  app:
    build:
      context: .
      secrets:
        - github_user
        - github_token
    environment:
      DATABASE_URL: postgres://${POSTGRES_USER}:${POSTGRES_PASSWORD}@db/${POSTGRES_DB}
      SELENIUM_HUB_URL: http://chrome:4444/wd/hub
      TEST_APP_HOST: app
      TEST_APP_PORT: 3001
    ports:
      - "${APP_PORT}:3000"
    volumes:
      - .:/app
    depends_on:
      - db
      - redis

  pgadmin:
    image: dpage/pgadmin4
    environment:
      PGADMIN_DEFAULT_EMAIL: ${PGADMIN_DEFAULT_EMAIL}
      PGADMIN_DEFAULT_PASSWORD: ${PGADMIN_DEFAULT_PASSWORD}
    ports:
      - "${PGADMIN_PORT}:80"
    depends_on:
      - db

  chrome:
    image: selenium/standalone-chrome
    environment:
      HUB_HOST: hub
    ports:
      - "4444:4444"

  mailcatcher:
    image: dockage/mailcatcher
    ports:
      - "${MAILCATCHER_PORT}:1080"

volumes:
  postgres-data:

secrets:
  github_user:
    environment: "GITHUB_USER"
  github_token:
    environment: "GITHUB_TOKEN"

Dockerfile

FROM ruby:3.2

RUN curl -sL https://deb.nodesource.com/setup_18.x | bash -
RUN curl -sL https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add -
RUN echo "deb https://dl.yarnpkg.com/debian/ stable main" | tee /etc/apt/sources.list.d/yarn.list
RUN apt-get update -qq && apt-get install -y nodejs yarn libpq-dev postgresql-client ruby-full
RUN mkdir /app

WORKDIR /app

RUN gem install rails

COPY Gemfile Gemfile.lock ./
RUN --mount=type=secret,id=github_user \
  --mount=type=secret,id=github_token \
  BUNDLE_GITHUB__COM=$(cat /run/secrets/github_user):$(cat /run/secrets/github_token) bundle install
COPY package.json yarn.lock ./
RUN yarn

# Copy the rest of the application code into the container
#COPY . .

# Precompile the assets
# RUN rails assets:precompile

EXPOSE 3000
CMD ["bin/dev"]