AppConfigFor Gem Version

Ruby gem providing Rails::Application#config_for style capabilities for non-rails applications, gems, and rails engines.


Add this line to your application's Gemfile:

gem 'app_config_for'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install app_config_for


Presume a typical rails database config at ./config/database.yml
One environment variable ('MY_APP_ENV', 'RAILS_ENV', or 'RACK_ENV') is set to 'development' or all are non existent.


default: &default
  site: <%= ENV.fetch("MY_APP_SITE", '') %>
  password: Slackware#1!

  <<: *default
  username: Linux

  <<: *default
  username: TestingWith

  <<: *default
  username: DefinitelyUsing

  color: 'Blue'


require 'app_config_for'

module Sample
  class App
    extend AppConfigFor
    def info
      puts "Current environment is #{App.env}"

      puts "Remote Host: #{}"

      # Can access same configuration in other ways
      puts "Username: self.class.config_for(:app)[:username]"
      puts "Password: App.config_for(App).username"

      # Access a different config
      if App.config_file?(:database)
        puts "Rails database config: App.config_for(:database)"

The following shows what can be expected

$ irb
3.0.3 :001> require_relative 'my_class'
 => true
3.0.3 :002> example =
 => #<MyApp::MyClass:0x000001655ac10460>
3.0.3 :003>
Curent environment is development
Remote Host:
Username: Linux
Password: Slackware#1!
Color: clear
Rails database config: {:adapter=>"sqlite3", :pool=>5, :timeout=>5000, :database=>"db/development.sqlite3"}
 => nil
3.0.3 :004> exit


After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to


Bug reports and pull requests are welcome on GitHub at This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.


The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the AppConfigFor project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.