Why?

If you have a Ruby web application that you want to use OpenID in, check out Rack::OpenID.

If you …

• have lots of applications and you only want to implement one OpenID consumer OR …
• you have a web app running in an environment (like Google AppEngine) where OpenID consumers don’t work properly

… check out Rack::OpenID::Proxy.

If you don’t need a proxy to be an OpenID consumer, this likely isn’t for you. I created this because we’ve been using Google AppEngine and OpenID doesn’t work very well on AppEngine.

How?

Rack::OpenID::Proxy runs as a standalone Rack application (or it can be run as middleware).

Let’s say you run this proxy on Heroku at http://openid-proxy.heroku.com.

From a different web application, when you want to authenticate a user against OpenID, redirect them to http://openid-proxy.heroku.com/openid?url=the-users.open-id-provider.com. This will redirect the user to the OpenID providers’ login and then redirect back to whatever URL your request originally came from (via the referer) with an extra querystring, eg: http://yoursite.com/original-path?token=1234abcd

Now the user is back on your site and has been through the OpenID process (via 1 simple redirect). To get the OpenID response (to find out if the login was successful), you can fetch the response via: http://openid-proxy.heroku.com/openid.json?token=1234abcd

Here’s an example consumer implementation written in Sinatra:

 1 require 'sinatra'
 2 require 'open-uri'
 3 
 4 PROXY = 'http://my-open-id-proxy.com'
 5 
 6 get '/' do
 7   if params['token']
 8     # this is the redirect coming back from the proxy.
 9     # the OpenID response is accessible using the token we were given.
10     response = open("#{ PROXY }/openid?token=#{ params['token'] }")
11     "OpenID response: #{ response }"
12   else
13     haml :openid_login_form
14   end
15 end
16 
17 post '/login' do
18   # redirect to the proxy to do the OpenID authentication for us.
19   # the proxy will redirect back to this app with a token param.
20   redirect "#{ PROXY }/openid?url=#{ params['openid-url'] }"
21 end
22 
23 __END__
24 
25 @@ openid_login_form
26 
27 %form{ :action => '/login', :method => 'post' }
28   %label
29     OpenID URL: 
30     %input{ :type => 'text', :name => 'openid-url' }
31   %input{ :type => 'submit', :value => 'Login via OpenID' }

http://github.com/devfu/rack-openid-proxy