GoogleAuth is a very, very trivial convenience wrapper around omniauth-google-apps that
makes a lot of assumptions, and requires much less setup.
Version 0.1.0 is Rails 4.x compatible. For Rails 3.x projects use version 0.0.4
gem 'google_auth'
# config/initializers/google_auth.rb
Rails.application.config.google_auth.domain = 'yourgoogleappsdomain.com'
# other options: 'user_class', 'path'. See source for details.
include GoogleAuth::Controller