Implements Travis CI Single Sign-On as a Rack middleware.
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README.md

Travis::SSO

Implements Travis CI Single Sign-On as a Rack middleware.

Dependencies are intentionally kept simple (rack and multi_json), so it fits in whatever stack the app has.

Usage

If an unauthenticated request is made through this middleware, an authentication handshake with the Travis API is performed.

Example Usage:

use Travis::SSO,
  mode: :single_page,                 # defaults to :callback
  endpoint: "http://localhost:3000"   # defaults to "https://api.travis-ci.org"

Session Authentication

use Rack::Session::Cookie, secret: 'change_me'
use Travis::SSO, mode: :session

Note: Usually Sinatra or Rails will set up the session for you. In either case, make sure the Travis::SSO middleware is added after the session middleware, otherwise it will not be able to store the user id in the session.

By default, it will store the user id in a session field called user_id. You can change that by passing in a :user_id_key option:

require 'sinatra'

enable :sessions
use Travis::SSO, mode: :session, user_id_key: 'foo'

helpers do
  def current_user
    @current_user ||= User.find session['foo']
  end
end

If you should set up a custom session store besides the standard, you can change the env key used by passing in :session_key:

use Rack::Session::Memcache, key: 'my_app.session1', secret: 'change_me'
use Rack::Session::Cookie, key: 'my_app.session2', secret: 'change_me'
use Travis::SSO, mode: :session, session_key: 'my_app.session1'

Keep in mind to protect against all these nasty session based attacks if you use this mode.

Single-Page Authentication

Authenticates a single GET request. Every subsequent GET request (that's going through the middleware) will need to go through the handshake again. This is more secure than session based authentication and is ideal for single page or JavaScript heavy applications.

use Travis::SSO, mode: :single_page

Custom Authentication with Callbacks

This is the default mode. When using this mode, you have to provide a :pass, :set_user and :authenticated? callback.

Each of these takes a Rack::Request instance as first argument. In addition, :set_user takes a hash with user information as a second argument.

The :pass callback will be called after successful login and the return value will be used as response. The :set_user callback will be called to store information about the user for later access. The :authenticated? callback will be called to check if the request is authenticated.

use Travis::SSO,
  pass:           -> r   { [301, {'Location' => '/'}, []]  },
  set_user:       -> r,u { r.session['token'] = u['token'] },
  authenticated?: -> r   { r.session.include? 'token'      }

Whitelisting URLs

use Travis::SSO,
  mode: :single_page,
  whitelist: "/img/*"

You can pass in a String, a Regular Expression or an Array of these.

If you need something more fancy, you can also add a whitelisted? callback:

use Travis::SSO,
  mode: :single_page,
  whitelisted?: -> r { r.user_agent =~ /Safari/ }

Limiting Users

Optionally, any mode takes an authorized? callback you can use to limit user access:

use Travis::SSO,
  mode: :single_page,
  authorized?: -> u { u['login'] == 'dhh' } # let only dhh use this app

The hash handed to the callback corresponds to the data returned by travis-api.

Two-Factor Authentication

The SSO middleware comes with two-factor authentication support built-in.

All you need to do is provide callbacks for storing and retrieving a secret value per user:

secrets = {} # storing secrets in memory, not a good idea

use Travis::SSO,
  mode: :single_page,
  get_otp_secret: -> user { secrets[user['login']] },
  set_otp_secret: -> user, secret { secrets[user['login']] = secret }

There are two additional callbacks: describe_otp(request, user) to generate the service description and generate_otp_secret(user) to override how the secret is generated.

Note that it currently does not support sending out text messages, you will have to use an application like Google Authenticator.

Helpers

This library ships with a simple helpers mixin, implementing a current_user method and aliasing it to user. It should work for both Rails controllers and Sinatra applications.

class HomeController < ApplicationController
  # assuming you use Travis::SSO as middleware
  include Travis::SSO::Helpers

  def index
    render text: "Hello, #{user.name}"
  end
end

In Sinatra

Travis::SSO can also be used as an Sinatra extension, in which case it will automatically pick session based or single page authentication depending on whether sessions have been enabled and will automatically pull in the helper methods.

Usage is pretty straight forward:

register Travis::SSO

get '/' do
  "Hello, #{user.name}!"
end

The middleware can be configured via the sso setting:

set :sso, whitelist: "/img/*"
register Travis::SSO

get '/' do
  "Hello, #{user.name}!"
end

Contributing

  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request