2025-04-13

Docker-compose Rails

Initialize repo.
```
git init
```

Add docker-compose.yml.

services:
  builder:
    image: ruby:3.4
    volumes:
      - .:/rails
    working_dir: /rails
    environment:
      - BUNDLE_PATH=/usr/local/bundle
      - RAILS_ENV=development
    # Replace my_app
    command: bash -c "gem install rails -v 8.0.2 && rails new . -n my_app --database=postgresql --force"

Run the builder.
```
docker-compose run builder
```

Add Dockerfile.dev for development.

FROM ruby:3.4

# Rails app lives here
WORKDIR /rails

# Install base packages
RUN apt-get update -qq && \
    apt-get install --no-install-recommends -y curl libjemalloc2 libvips postgresql-client && \
    rm -rf /var/lib/apt/lists /var/cache/apt/archives

# Install packages needed to build gems
RUN apt-get update -qq && \
    apt-get install --no-install-recommends -y build-essential git libpq-dev libyaml-dev pkg-config && \
    rm -rf /var/lib/apt/lists /var/cache/apt/archives

Remove the builder section and add services web and db.

services:
  web:
    build:
      dockerfile: ./Dockerfile.dev
    command: bash -c "rm -f tmp/pids/server.pid && rails server -b 0.0.0.0"
    environment:
      - HISTFILE=.bash_history
      # Replace my_app_
      - DATABASE_URL=postgres://postgres:password@db:5432/my_app_${RAILS_ENV:-development}
      - RAILS_ENV=${RAILS_ENV:-development}
    volumes:
      - .:/rails
      - bundle_cache:/usr/local/bundle
      - node_modules:/rails/node_modules
    ports:
      - "3000:3000"
    depends_on:
      - db
    stdin_open: true
    tty: true

  db:
    image: postgres:16
    environment:
      POSTGRES_PASSWORD: password
      POSTGRES_USER: postgres
      # Replace my_app_
      POSTGRES_DB: my_app_${RAILS_ENV:-development}
    volumes:
      - postgres_data:/var/lib/postgresql/data
    ports:
      - "5432:5432"

volumes:
  postgres_data:
  bundle_cache:
  node_modules:

Spin up the services.
```
docker-compose up
```