You will most probably need to have at least one particular case where you need to store configuration values for your Rails application. Saving these types of values in the environment is one of the principles of a twelve-factor app. It is thus recommended to use a separate file and use environment variables inside your code so that you do not have to change the same value in multiple places. This, however, is not something that you can do really easily unless you use something really helpful like dotenv.
Dotenv is a Ruby gem that during the bootstrap loads variables from a .env file into the environment that you are running your application.
It is really to use and all you have to do to install it is place the following line in your Gemfile:
gem ‘dotenv-rails’, groups: [:development, :test]
Then, of course, you need to run bundle.
Now you need to place your configurations inside .env file in the root of your project:
AUTH0_CLIENT_ID=YOURAUTH0CLIENTID
SECRET_KEY=YOURSECRETKEYGOESHERE
You can then access them using ENV.fetch[‘SECRET_KEY’] or ENV[‘SECRET_KEY’]. Note that if you use ENV.fetch[], you can learn about unset environment variables during the deploy.
According to its README file, dotenv is initialized in your Rails app during the before_configuration callback, which is fired when the Application constant is defined in config/application.rb with class Application < Rails::Application. If you need it to be initialized sooner, you can manually call Dotenv::Railtie.load.
You can view its source code and learn more about it by going on Github.
