Docker Compose: Ruby on Rails Example

A simple example of using Docker Compose for developing and deploying Ruby on Rails applications.

Read the full article on jigarius.com.

Getting started

Follow the steps mentioned under existing app or new app depending on your situation. That will ensure that the ror directory is in order. After that, follow these steps:

• Destroy any existing containers with conflicting names.
• Copy .env.example to .env and modify (if required).
• Create config/database.yml based on .docker/ror/example.database.yml.
• Build an image for Ruby on Rails:

  docker-compose build
  

• Boot up the app by running:

  docker-compose up
  

• Create databases by running:

    docker-compose exec web rake db:create
  

Cool! Now your Rails app should be available at localhost:3000.

Existing app

• Delete the contents of the ror directory.
• Put the files of your existing Rails app in the ror directory.
  • The Gemfile should be at ror/Gemfile.

New app

If you want to start with a Rails app from scratch,

• Create the following files:
  • Gemfile: You can base this on .docker/ror/example.Gemfile.
  • Gemfile.lock: An empty file.
• Run the following command to install Rails. You can modify the params for the rails new command as needed.

  docker-compose run --no-deps web rails new . --force --database=postgresql
  

  • For a quick Rails install, use the --minimal flag.

Commands

Here are some helpful commands.

• docker-compose start: Starts app containers.
• docker-compose stop: Stops app containers.
• rake -T: For some other helpful commands.

See docker compose docs for further info on Docker Compose.