[GUIDE] Starting a new Ruby on Rails project in docker

rails.md

Bootstrap project

1. Initialize your project folder: git init

2. Create your project files with a ruby image:

   docker run -it -v .:/rails/<app_name> -w /rails/<app_name> ruby:latest /bin/bash
   gem install rails
   rails new .
   exit
   

3. Configure the rails web console to work in docker in development.rb:

   # Allow IRB in browser for a docker environment
   config.web_console.permissions = '0.0.0.0/0'
   

Simple environment

1. Create a docker-compose.yml:

   services:
      app:
        image: ruby:<version from gemfile>
        command: ./bin/rails server -b 0.0.0.0
        ports:
          - "3000:3000"
        volumes:
          - .:/rails/<app_name>
          - bundle:/usr/local/bundle
        working_dir: /rails/<app_name>
   volumes:
     bundle:
   

2. Setup the application: docker compose run app bin/setup

3. Start the application: docker compose up

Advanced environment

1. Copy the Dockerfile into a new Dockerfile.dev

   1. Remove any environment variables
   2. Modify bundle install step to only bundle install
   3. Remove precompilation steps
   4. Test it with docker build Dockerfile.dev .

2. Create a docker-compose.yml:

   services:
      app:
        build:
          context: .
          dockerfile: Dockerfile.dev
        command: ./bin/rails server -b 0.0.0.0
        ports:
          - "3000:3000"
        volumes:
          - .:/rails
   

Postgres

1. Setup docker service:

   services:
     app:
       # ...
       environment:
         DATABASE_HOST: db
         DATABASE_PASSWORD: password
       # ...
     db:
       image: postgres:15
       environment:
         POSTGRES_PASSWORD: password
       volumes:
         - db:/var/lib/postgresql/data
   volumes:
     db:
   

2. Run db docker service: docker compose up db

3. docker compose run app bin/rails db:system:change --to=postgresql

4. docker compose run app bin/setup

5. Modify ./config/database.yml:

   default: &default
     adapter: postgresql
     encoding: unicode
     host: <%= ENV["DATABASE_HOST"] %>
     password: <%= ENV["DATABASE_PASSWORD"] %>
     # For details on connection pooling, see Rails configuration guide
     # https://guides.rubyonrails.org/configuring.html#database-pooling
     pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
     username: postgres
   

Fly.io (WIP)

1. Setup docker volume:

   services:
     app:
       # ...
       volumes:
         # ...
         - fly:/root/.fly
       # ...
   volumes:
     fly:
   

2. docker compose run app /bin/bash

3. curl -L https://fly.io/install.sh | sh

4. /root/.fly/bin/fly auth login

5. /root/.fly/bin/fly launch NOTE: Use Web UI to confirm settings!

6. After which you can just deploy: docker compose run app /root/.fly/bin/fly deploy