Workbench authentication process » History » Revision 23
Revision 22 (Peter Amstutz, 11/21/2014 07:46 PM) → Revision 23/26 (Peter Amstutz, 11/21/2014 07:48 PM)
h1. Workbench authentication process
(work in progress updating for multiple authentication methods)
# In workbench, when the browser goes to a page, it checks for a session or @?api_token=xxx@ in the URL for the API token. If no API token is found, the brower is directed to the workbench "welcome" page @workbench/app/views/users/welcome.html.erb@
# In workbench, the "welcome" page has a "log in" button that directs the browser to the API server login URL, with a @?return_to=xxx@ link embedded in the URL.
## Workbench may provide a @auth_provider@ parameter in the "log in" button form in order to select an SSO provider, such as "Google OAuth2" or "Google OpenId"
# In API server, the 'login' endpoint goes to @UserSessionsController#login@ in the API server. This redirects the browser to @/auth/joshid?return_to=xxx?auth_provider=zzz@
# In API server, @/auth/joshid@ is intercepted by the "OmniAuth":https://github.com/intridea/omniauth Rack middleware and invokes the @josh_id@ OmniAuth strategy.
## The @josh_id@ OmniAuth strategy is implemented in @arvados/services/api/lib/josh_id.rb@ and is a subclass of @OmniAuth::Strategies::OAuth2@
## OmniAuth starts the "request_phase" of @OmniAuth::Strategies::OAuth2@. This redirects the browser to @#{options[:custom_provider_url]}/auth/josh_id/authorize?return_to=xxx?auth_provider=zzz@ using CUSTOM_PROVIDER_URL defined in @arvados/services/api/config/initializers/omniauth.rb@
# In sso-provider, @/auth/josh_id/authorize@ is routed to @AuthController#authorize@, and is intercepted by @before_filter :authenticate_user!@ (part of the "devise gem":https://github.com/plataformatec/devise)
## @save_auth_provider@ records the @:auth_provider@ parameters in the session
## @devise :omniauthable, :omniauth_providers => [:google_oauth2]@ configures @sso-provider/app/models/user.rb@ to use the "google_oauth2" strategy
## @authenticate_user!@ is not explicitly defined but instead monkey patched into the controller in @devise/lib/devise/controllers/helper.rb@
## @authenticate_user!@ calls @warden.authenticate!@ (@warden/lib/warden/proxy.rb@) with a scope of @:user@ ("warden":https://github.com/hassox/warden is another Rack-based authentication gem)
## Warden proxy tries the TokenAuthenticatable and DatabaseAuthenticatable strategies, but these strategies fail and it raises a :warden exception. This causes it to call @failure_app@ which is set up in @devise/lib/devise.rb@ to be @Devise::Delegator.new@
## This calls @devise/lib/devise/failure_app.rb@ which saves the attempted path in the session ("user_return_to") using @store_location!@, then redirects the browser to @new_user_session_path@ (@/users/sign_in@)
# In sso-provider @/users/sign_in@ routes to the SSO @SessionsController#new@ which subclasses @Devise::SessionsController@
## @SessionsController#new@ redirects the browser to @/users/auth/#{session[:auth_provider]}@
# In sso-provider, OmniAuth intercepts @/users/auth/:auth_provider@
## OmniAuth is configured with a path prefix of @/users/auth@ by devise
## @sso-provider/config/initializers/devise.rb@ configures the auth_providers
## :google_oauth2
### Redirects to @client_options.site@ + @client_options.authorize_url@ which is https://accounts.google.com/o/oauth2/auth
## :google (OpenId 2.0) (deprecated)
### @sso-provider/config/initializers/devise.rb@ configures a @:open_id@ omniauth strategy named 'google')
### This enters the request phase at @omniauth-open-id/lib/omniauth/strategies/open_id.rb@
### This creates a rack layer with @Rack::OpenID.new@ (the @rack-openid@ gem) executes it with @call@
### The Rack layer passes through the request to the underlying @@app@ and checks for a 401 response code, if so it calls @begin_authentication@
### @begin_authentication@ constructs an @::OpenID::Consumer@ object and calls redirects the browser to @open_id_redirect_url@, which finally takes us to a Google login page (after some redirects within Google).
# Google presents the user with a login page, and directs the browser to the sso-server at @/users/auth/:auth_provider/callback@ after a successful login (after more redirects within Google)
# In sso-provider, Omniauth intercepts this and calls @callback_phase@ in the provider's omniauth module
## :google_oauth2
### This uses the callback code to initiate a request for an access token and other user information from https://accounts.google.com/o/oauth2/token
### It uses the response to provision the Rack environment with the user information
## :google (OpenId 2.0) (deprecated)
### The callback phase calls @openid_response@
### @openid_response@ creates a rack layer with @Rack::OpenID.new@ (the @rack-openid@ gem) executes it with @call@. This provisions the Rack environment with info from the OpenID callback.
## Request handling continues to sso-provider where it routes to @Users::OmniauthCallbacksController#google@
## This calls @find_for_identity@ on the @User@ model which finds a user record with a matching omniauth @uid@ (the @identity_url@ column in the users table), or creates and saves a new user record with the @uid@.
## The callback also saves the first_name and last_name of the user.
## This calls @sign_in_and_redirect@ defined in @devise/lib/devise/controllers/helpers.rb@
## This calls set_user in Warden, which uses @Warden::SessionSerializer@ to save the user associated with the session
## This redirects the browser to @stored_location_for@ which returns the value of @user_return_to@ in the session, which is @/auth/josh_id/authorize@ from step 5.
# In sso-provider, @/auth/josh_id/authorize@ routes to @AuthController#authorize@, and passes @authenticate_user!@ because the there is now a user associated with the session.
## @authorize@ builds an @AccessGrant@ using the @state@ token from the request
## @authorize@ redirects the browser to @params[:redirect_uri]@ which is @/auth/josh_id/callback@ (this is the oauth callback on the API server, saved from step 5)
# In API server, @/auth/josh_id/callback@ is intercepted by @OmniAuth::Strategies::OAuth2@ and calls @callback_phase@.
## @OmniAuth::Strategies::OAuth2@ creates a @::OAuth2::Client@ and calls @get_token@ to convert the "authorization_code" into a "oauth_token"
## The API server makes a request to the sso-provider at @/oauth/token@
# In the sso-provider, @/oauth/token@ is routed to @AuthController#access_token@
## This first checks @Client.authenticate@ which verifies that @client_id@ (@app_id@) and @client_secret@ (@app_secret@) are recognized
## Next it calls @AccessGrant.authenticate@ which verifies that @code@ and @client_id@ are recognized
## This renders an JSON API response with the @access_token@, @refresh_token@ and @expires_in@ fields which are returned to the API server.
# The API server, back in OmniAuth::Strategies::OAuth2, receives the response and saves the @access_token@.
## Request processing continues and routes to @UserSessionsController#create@
## API server gets the OmniAuth object and looks up the Arvados API user by @identity_url@
## The session is provisioned with the Arvados user id
## @if params.has_key?(:return_to)@ then it calls @send_api_token_to@
## @send_api_token_to@ creates a new ApiClientAuthorization
## It redirects the browser to the @:return_to@ after adding @api_token=xxx@ to the query portion of return_to
# The browser is finally redirected to workbench to with @api_token=xxx@
## Workbench adds the api_token to the session, and redirects the browser one last time to the same location with @?api_token@ stripped from the URL query portion.