Rack-CAS is simple Rack middleware to perform CAS client authentication.

• Rack based
• Framework independent
  Works with, but doesn't depend on Rails, Sinatra, etc.
• Minimal dependencies
  Current gem dependencies are rack, addressable and nokogiri.
• Supports CAS extra attributes
  Extra attributes are a mess though. So let me know if your brand of CAS server isn't supported.
• Single sign out
  One of the included session stores must be used.
• Rake tasks to prune stale sessions
  rack_cas:sessions:prune:active_record and rack_cas:sessions:prune:mongoid

• Ruby >= 1.9.2
• A working CAS server

Add gem 'rack-cas' to your Gemfile and run bundle install

Once the necessary gems have been installed, in your config/application.rb add:

config.rack_cas.server_url = 'https://cas.example.com/'

If the the server URL depends on your environment, you can define it in the according file: config/environments/<env>.rb

If you wish to enable single sign out you'll need to modify your configuration as below.

Set the session_store in your config/application.rb:

require 'rack-cas/session_store/active_record'
config.rack_cas.session_store = RackCAS::ActiveRecordStore

Edit your config/initializers/session_store.rb file with the following:

require 'rack-cas/session_store/rails/active_record'
YourApp::Application.config.session_store :rack_cas_active_record_store

Run:

rails generate cas_session_store_migration
rake db:migrate

Set the session_store in your config/application.rb:

require 'rack-cas/session_store/mongoid'
config.rack_cas.session_store = RackCAS::MongoidStore

Edit your config/initializers/session_store.rb file with the following:

require 'rack-cas/session_store/rails/mongoid'
YourApp::Application.config.session_store :rack_cas_mongoid_store

Add gem 'rack-cas' to your Gemfile and run bundle install

Add the following to your config.ru file:

require 'rack/cas'
use Rack::CAS, server_url: 'https://login.example.com/cas'

Single sign out support outside of Rails is currently untested. We'll be adding instructions here soon.

If you have some parts of your app that should not be CAS authenticated (such as an API namespace), just pass exclude_path to the middleware. You can pass in a string that matches the beginning of the path, a regular expression or an array of strings and regular expressions.

use Rack::CAS, server_url: '...', exclude_path: '/api'
use Rack::CAS, server_url: '...', exclude_path: /\.json/
use Rack::CAS, server_url: '...', exclude_paths: ['/api', /\.json/]

The same options can be passed to FakeCAS.

use Rack::FakeCAS, exclude_path: '/api'

Your app should return a 401 status whenever a request is made that requires authentication. Rack-CAS will catch these responses and attempt to authenticate via your CAS server.

Once authentication with the CAS server has completed, Rack-CAS will set the following session variables:

request.session['cas']['user'] #=> johndoe
request.session['cas']['extra_attributes'] #=> { 'first_name' => 'John', 'last_name' => ... }

NOTE: extra_attributes will be an empty hash unless they've been configured on your CAS server.

Testing your controllers and such should be as simple as setting the session variables manually in a helper.

def set_current_user(user)
  session['cas'] = { 'user' => user.username, 'extra_attributes' => {} }
end

Integration testing using something like Capybara is a bit trickier because the session can't be manipulated directly. So for integration tests, I recommend using the provided Rack::FakeCAS middleware instead of Rack::CAS.

require 'rack/fake_cas'
use Rack::FakeCAS

If you are using Rails, FakeCAS is automatically used in the test environment by default. If you would like to activate it in any other environment, add the following to the corresponding config/environments/<env>.rb:

config.rack_cas.fake = true

Then you can simply do the following in your integration tests in order to log in.

visit '/restricted_path'
fill_in 'username', with: 'johndoe'
fill_in 'password', with: 'any password'
click_button 'Login'

NOTE: The FakeCAS middleware will authenticate any username with any password and so should never be used in production.