Dockerized Rails template

This template aims to create a simple Rails application with Docker, testing tools and linter already configured.

Especially intended for coding challenges.

Up and running

Add database configuration:

$ cp config/database.yml{.sample,}

Change the database name for development and test environments. Look for the FIXME comments inside that file.

Specify the same database name as the default value of DB_NAME variable in Makefile, keeping the environment as suffix.

In docker-compose.yml file, specify the desired image name.

Commands

The first time you will need to build the application:

$ make start-build [SERVICES="<whitespace-separated services>"] [WORKDIR="<absolute path>"] [PORT=<port>]

Examples:

$ make start-build
$ make start-build SERVICES="app db"
$ make start-build WORKDIR=/rails
$ make start-build PORT=3001

Combine options as needed.

The server will be running on port 3000 by default, unless otherwise specified.

Generate config/master.key and config/credentials.yml.enc with following command:

$ make edit-credentials

VIM is used inside the container to edit the encrypted credentials.

Restart server without restarting containers:

$ make restart-server

Other useful commands

Start containers without building them:

$ make start [PORT=<port>]

Restart containers:

$ make restart-build [PORT=<port>]
$ make restart [PORT=<port>]

Stop containers:

$ make stop

Destroy containers:

$ make destroy

Check Makefile for other useful commands.

Application

The application has been generated using latest Rails version at the moment of writing. I'll try to keep it updated as new versions are released.

The same goes for Ruby.

Ensure you use the same version in .ruby-version file and the RUBY_VERSION argument in every Dockerfile.

The application was generated with following command:

$ docker compose exec app bundle exec rails new . --database postgresql --skip-git --skip-keeps --skip-asset-pipeline --skip-turbolinks --skip-test --skip-system-test --skip-spring --skip-bootsnap --skip-jbuilder --skip-javascript

If you need an only API application, configure it accordingly. Follow the official documentation.

Note that you could remove any directory or file that you know you won't need.

Database

This code assumes Postgres is used. In case you prefer to use another database, change the configuration accordingly.

Run following command:

$ docker compose exec app rails db:system:change --to=<new database>

Change it manually in other Dockerfiles.

More details here.

Testing

RSpec is the testing framework of choice.

Check the configuration in following files to adapt it if necessary:

• .rspec
• spec/rails_helper.rb
• spec/spec_helper.rb

FactoryBot is used instead of fixtures.

Database Cleaner Adapter for ActiveRecord is used to clean the database after running the test suite. For that, you need to specify the type database.

Example:

RSpec.describe "Create user", type: %i[request database] do
  # omitted
end

Linter

RuboCop is the linter of choice.

Check the configuration in .rubocop.yml file to adapt it if necessary.

Possible improvements

A non-root user is configured to run the application. To be able to successfully add new gems to the project, the owner of the Bundler path, defined in every Dockerfile, is changed in the final stage of the build process. Notice that that process is quite slow at this moment.