Heroku SSO authentication strategy for Devise

Add devise-heroku to your Gemfile

  gem 'devise-heroku', git: "http://github.com/aschepis/devise-heroku.git"

Add heroku_sso_authenticable to your default warden strategies in your devise.rb file

  manager.default_strategies(:scope => :user).unshift :heroku_sso_authenticable

Add an initializer to set devise-heroku configuration parameters (config/initializers/devise_heroku.rb)

  DeviseHeroku.setup do |config|
    config.resource = User
    config.sso_salt = "2D4g4a84jf03"
    config.redirect_path = '/'
  end

That should do it! Restart your rails server and you should be able to verify that your app works with Heroku SSO by testing it with kensa

  kensa sso 3865

Issues and Pull Requests are welcome! This code is very preliminary and I got it up and working for my project. There are a number of things that I don't love but I wanted to put this out there to benefit others.