code42template is the base Rails project used at Codeminer 42.

gem install code42template -v 2.1.0



This is the base application used at Codeminer 42. It uses Rails 5 to manage the backend and Node.js / Webpack to manage the frontend. The purpose of this project is to:

  • Provide a minimal and well-configured application generator.
  • Improve some Rails defaults.
  • Unleash the full power of the JavaScript ecosystem within Rails by making it a first class citizen. We replace JS sprockets with Webpack.
  • Enforce code style guidelines.
  • Provide basic security.
  • Have Ruby and JS test frameworks configured out of the box with a few hand-picked tools.
  • Provide opinionated defaults on infrastructure: Travis for CI and Heroku deploys working out of the box. We want apps to leverage the best Heroku has to offer, such as decreased devops maintenance burden, pipelines, review apps, etc.

This template does NOT aim to:

  • Encourage having too many dependencies. Dependencies are not cheap, and each bundled tool must have a good reason to be included.
  • Make you use JavaScript for everything, but rather to provide better tools to work with the language. Just because we use Webpack it does not mean you have to turn your app into an SPA.
  • Provide "pattern" gems (e.g. decorator). Patterns are usually project-specific and most of them can be achieved without any gems or libraries.
  • Be a silver bullet. This is tailored for the majority of Rails applications you may want to build, but we know it won't work sometimes.



Install the gem:

gem install code42template

This will make the code42template command accessible throughout your PATH.

Configuring your environment


development and test databases are automatically setup for you. While running the generator it's assumed that:

  • The PostgreSQL server is running.
  • You have a PostgreSQL user named after your UNIX login.
  • Your PostgreSQL user has a blank password.

It's OK if your PG settings happen to be different from this; DB creation will fail, but you can do it manually thereafter.

At a basic level, here's how to setup PostgreSQL on Linux:

# Creates a user
sudo -u postgres createuser -s my_user_name

# Runs psql
sudo -u postgres psql

# Change your use password within psql. Leave it blank.
[local] thiago@thiago=# \password my_user_name


Automatic Heroku setup is optional, but if you want to use it we assume you've already logged in with your Heroku credentials. If you haven't, you'll need to run heroku login. Also remember to set the correct account if you happen to use the multiple accounts plugin.

Generating your app

You can generate a new app with the following command:

code42template myapp

To generate and configure your new app with Heroku:

code42template myapp --heroku true

Starting up your app

$ cd my_app_folder
$ foreman start

This command runs Webpack dev server, Rails server and Sidekiq all at once. Note that Your redis server has to be up and running because of Sidekiq. To customize these processes you can edit Procfile.

Now you can work as you'd usually work in any Rails application, with automatic Ruby and JS file reloads out of the box.

Basic hands-on guide

App setup

Your team can use the following command after cloning the git repository:



Deploy your app with the following command:

# Replace `MY_ENV` with `production` or `staging`.
bin/deploy MY_ENV

This command pushes your code to Heroku, migrates your database and restarts your dynos. It will work out of the box if you've generated your app with --heroku true. If not, please create staging and production git remotes pointing to the respective Heroku remotes.

Health check

Check your app's health with the rake health command. It runs the following tasks:

  • rspec runs your Ruby and Rails specs.
  • If you app happens to be below 90% test coverage the rspec command will fail.
  • npm run test: runs JS unit and integration tests
  • bundle-audit and brakeman check if your app does not have basic security holes.
  • rubocop makes sure your code adheres to style guidelines.
  • eslint makes sure your JavaScript code conforms to fine standards

Continuous integration

A travis.yml file is also included: it runs the rake health command, among other setup tasks. You must still manually configure your remote repo with Travis integration, though.

Improved JavaScript

JS files must live at the app/assets/javascripts folder. JS packages can be managed with NPM and the package.json file.

You can write your JS code in ES2015 because of babel. ES2015 Import statements will automatically work without having to specify the full path.


We still use the asset pipeline for CSS.


Ruby tests

Use the following command to run all your specs:


We use the following tools:

Refer to the rspec-rails to learn which kinds of specs are available.

Note that you can require the following files to setup your tests:

  • For light unit tests you can require spec_helper.rb. It won't boot up the Rails environment.
  • For tests needing Rails you can require rails_helper.rb.
  • For feature tests require feature_helper.rb. It will compile your assets and make feature tests run correctly.

Regarding feature tests, they are configured to run seamlessly with Webpack.

JavaScript tests

JavaScript tests must live at the spec/javascripts folder. Some smoke tests are included in every app.

  • mocha is used for unit tests. Unit tests must not depend on global JS objects such as window. They must live at spec/javascripts/unit and can be run with:

      npm test:unit
      npm test:unit:watch # runs tests automatically in every change
  • karma and phantomjs are used for integration tests. That means you can use browser-only global JS objects such as window. They must live at spec/javascript/integration and can be run with:

      npm test:integration
      npm test:integration:watch
  • Run all the tests (unit + integration) with the following command:

      npm test
  • Debug your tests in the browser with webpack-dev-server. This command will output a URL where you can run all tests:

      npm test:browser

JavaScript: eslint

To run eslint over all JS files issue the following command:

    npm run lint

JavaScript: sinon

The template comes with sinon already pre-configured. Sinon is a popular mocking and stubbing tool for JavaScript. To import it in a test file use the following ES6 import instruction:

    import sinon from 'sinon';

Application server

We use puma as our application server, which happens to be Heroku's default recommendation.

Background jobs

Our tool of choice is Sidekiq, which is configured as ActiveJob's backend. We include a sidekiq.yml configuration file with default settings, but you are encouraged to tune it to your application needs.


Performance and Profiling

  • rack-mini-profiler for helping out with performance issues
  • spring for fast Rails actions via pre-loading
  • bullet yeah, it's very easy to miss out N+1 queries, that's why we include this gem by default

Spring binstubs are automatically generated within the bin folder.

Environment variables

  • Dotenv for loading environment variables


The template uses the Suspenders gem from Thoughtbot as starting point.