How to create tons of Rails applications

This article explains why, and how to quickly create as much Rails applications as you need, using any desired version of Rails.

1. Motivation

At BootrAils, we are using this script every (working !) day. It allows you to :

  • grab any concept,
  • isolate a bug quickly,
  • play with new Rails features,

… without any side effect.

Side note for beginners : It’s also an excellent way to improve your Ruby-on-Rails skills. The more you create new apps from scratch, the more you understand the directory structure, the philosophy, and the internals of Rails.

2. The trick

Open ~.bash_profile on your linux-based computer.

We will create a bash function, named cnra (an acronym that means “create new rails application”). Acronyms are very handy to avoid remembering every shortcut.

# inside ~.bash_profile

# Usage :
# $> cnra myapp 7.0.0 --minimal --database=postgresql
cnra ()
  # create dir, dive into dir, require desired Rails version
  mkdir -p -- "$1" && cd -P -- "$1"
  echo "source ''" > Gemfile
  echo "gem 'rails', '$2'" >> Gemfile
  # install rails, create new rails app
  bundle install
  bundle exec rails new . --force ${@:3:99}
  bundle update

  # Create a default controller
  echo "class HomeController < ApplicationController" > app/controllers/home_controller.rb
  echo "end" >> app/controllers/home_controller.rb

  # Create a default route
  echo "Rails.application.routes.draw do" > config/routes.rb
  echo '  get "home/index"' >> config/routes.rb
  echo '  root to: "home#index"' >> config/routes.rb
  echo 'end' >> config/routes.rb

  # Create a default view
  mkdir app/views/home
  echo '<h1>This is h1 title</h1>' > app/views/home/index.html.erb

  # Create database and schema.rb
  bin/rails db:create
  bin/rails db:migrate

Note the trick ${@:3:99} that means “all remaining CLI args, from the 3rd one to the last one.”

Otherwise, comments should be self-explanatory. If not, just contact us 🙂

Now type

$> source ~/.bash_profile

So that your terminal will be aware of what changed inside your .bash_profile.

3. Usage

Open your terminal

$> cnra myapp 7.0.0 --minimal -d=postgresql

1st CLI arg is “myapp” : the name of the new app 2nd CLI arg is 7.0.0 : the version of Rails you want to try 3rd CLI arg is –minimal -d=postgresql : PostGre is a production-ready database you can easily use locally.

Note that --minimal and -d=postgresql are optionals.

4. Going further

We personally like the minimal flag (to avoid all the default gems we probably won’t need), and the “postgresql” database – a production-ready, widely used database in the Ruby-on-Rails world. So we use another shortcut, based on the previous one.

cnra7mp() {
  cnra myapp 7.0.0 --minimal -d=postgresql

All we have to do now each time we want to try something with Rails is the following :

$/workspace> cnra7mp
$/workspace/myapp> bin/rails server

And voilà ! A new Rails application up and running, no need to create the database, or build a default welcome page : our app is ready for experimentations.

5. All available options

If you need to know all the options when creating a new Rails application, see

Enjoy !

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