CSC/ECE 517 Spring 2015/ch1b 21 QW

Omniauth

Omniauth is a Ruby authentication framework aimed to integrated with various types of authentication providers. It can be hooked up to any system, from social network to enterprise systems to simple username and password authentication<ref>https://github.com/intridea/omniauth/wiki</ref>.OmniAuth is a library extremely easy to use. It is designed to be a black box that you can send your application's users into when you need authentication and then get information back. OmniAuth was intentionally built not to automatically associate with a User model or make assumptions about how many authentication methods you might want to use or what you might want to do with the data once a user has authenticated.

The topic writeup for this page can be found here.

Background

Why Omniauth

With web application booming, most users login hundreds of services every day and won't expect to create unique login and password for each service. So intridea releases a standard library to provide multi-provider authentication for web applications in 2010. So far, thousands of users take advantage of the simple, powerful and secure authentication with OmniAuth in their web applications. From social networking sites like Facebook, Twitter, LinkedIn, to file- or media-sharing sites like Youtube, Github, to search engine sites like Google and Bing, to online e-commerce sites like Amazon and beyond, developers are relying on OmniAuth to handle user authentication in their systems. Here intridea lists some community-curated sites that are using OmniAuth to streamline authentication. Omniauth has following advantages:

Simple
Powerful
Flexible
Secure

In order to use Omniauth for authentication, developers can create and leverage one or more strategies released individually as RubyGems from different providers for OmniAuth. Each strategy is a Rack Middleware.

Rack Middleware

Rack provides a standard interface for developing web applications supporting Ruby and Ruby framework. And Rack middleware is a way to filter a request and response coming into your application<ref>http://railscasts.com/episodes/151-rack-middleware</ref>. Rack has quite simple architecture:

An object that responds to the call method
Taking the environment hash as a parameter
Returning an Array with three elements: status code, environment hash and response body

We can install Rack with following command:

$ gem install rack

Then we're going to create a Rack configuration file with extension .ru in your Rails application's root directory. That instructs Rack::Builder what middleware should it use and in which order. Or to say how to combine various internal and external middlewares to form a complete Rails Rack application<ref>http://guides.rubyonrails.org/rails_on_rack.html</ref>. Rack::Builder is Rails equivalent of ActionDispatch::MiddlewareStack.

#Rails.root/config.ru
require 'rack'

To use rackup to started up your created app, you can put the following code inside config.ru<ref>http://guides.rubyonrails.org/rails_on_rack.html</ref>. And then run rackup command:

require ::File.expand_path('../config/environment', __FILE__)
 
use Rails::Rack::Debugger
use Rack::ContentLength
run Rails.application

$ rackup config.ru

Creating a Middleware filter is just creating a Ruby class. Here is an simplest example:

# ResponseTimer.rb
class ResponseTimer
  def initialize(app)
    @app = app       
  end                

  def call(env)      
    @app.call(env)   
  end                
end

By binding HTTP requests and responses together in the simplest way, it unifies and distills the API for web servers, web frameworks, and software into a single method call.

Rails also provides some simple configuration interface config.middleware for adding, removing and modifying the middlewares in the middleware stack via application.rb or the environment specific configuration file environments/<environment>.rb. You can check out these methods by view Configuring Middleware Stack part of <ref>http://guides.rubyonrails.org/rails_on_rack.html</ref>.

Getting Start

Each OmniAuth strategy is a Rack Middleware, which means it can be used the same way as other Rack middleware. Here we introduce some simple steps to illustrate how to use Twitter strategy for OmniAuth.<ref>https://github.com/intridea/omniauth</ref>

Installing

First start by adding this gem to your Gemfile:

gem 'omniauth-twitter'

If you need to use the latest HEAD version, you can do so with:

gem 'omniauth-twitter', :github => 'arunagw/omniauth-twitter'

Usage

Because OmniAuth is built for multi-provider authentication, you need to build multiple strategies. For this, the Rack middleware OmniAuth::Builder class gives an easy way to build up your list of OmniAuth strategies for use in your application.

Below is an example that you can put into a Rails initializer at config/initializers/omniauth.rb or add it to your middleware:

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :developer unless Rails.env.production?
  provider :twitter, ENV['TWITTER_KEY'], ENV['TWITTER_SECRET']
end

You can create twitter application here, also, you can obtain "TWITTER_KEY" and "TWITTER_SECRET" here:

Integrating OmniAuth into Rails Application

To use OmniAuth, you need only to redirect users to /auth/:provider , where :provider is the name of the strategy (for example, developer or twitter ). From there, OmniAuth will take over and take the user through the necessary steps to authenticate them with the chosen strategy.

Once the user has authenticated, OmniAuth simply sets a special hash called the Authentication Hash on the Rack environment of a request to /auth/:provider/callback. This hash contains as much information about the user as OmniAuth was able to glean from the utilized strategy. You should set up an endpoint in your application that matches to the callback URL and then performs whatever steps are necessary for your application.

For example, in a Rails app you can add a line in routes.rb file like this:

get '/auth/:provider/callback', to: 'sessions#create'

Then you can have SessionsController with code that looks something like this:

class SessionsController < ApplicationController
  def create
    @user = User.find_or_create_from_auth_hash(auth_hash)
    self.current_user = @user
    redirect_to '/'
  end

  protected

  def auth_hash
    request.env['omniauth.auth']
  end
end

The omniauth.auth key in the environment hash gives the Authentication Hash which will contain information about the just authenticated user including a unique id, the strategy they just used for authentication, and personal details such as name and email address as available.

Note that OmniAuth does not perform any actions beyond setting some environment information on the callback request. It is entirely up to you how you want to implement the particulars of your application's authentication flow.

Logging

OmniAuth supports a configurable logger. By default, OmniAuth will log to STDOUT but you can configure this using OmniAuth.config.logger:

# Rails application example
OmniAuth.config.logger = Rails.logger

Other Examples

OmniAuth Facebook

Installing

To use Facebook OmniAuth Strateges<ref>https://github.com/mkdynamic/omniauth-facebook</ref>, first, add this gem into your Gemfile, and then run bundle install:

gem 'omniauth-facebook'

Usage

Adding the middleware to a Rails app in config/initializers/omniauth.rb:

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :facebook, ENV['FACEBOOK_KEY'], ENV['FACEBOOK_SECRET']
end

Configuring

Option name	Default	Explanation
`scope`	`email`	A comma-separated list of permissions you want to request from the user. See the Facebook docs for a full list of available permissions
`display`	`page`	The display context to show the authentication page. Options are: `page`, `popup` and `touch`. Read the Facebook docs for more details
`image_size`	`square`	Set the size for the returned image url in the auth hash. Valid options include `square` (50x50), `small` (50 pixels wide, variable height), `normal` (100 pixels wide, variable height), or `large` (about 200 pixels wide, variable height). Additionally, you can request a picture of a specific size by setting this option to a hash with `:width` and `:height` as keys. This will return an available profile picture closest to the requested size and requested aspect ratio. If only `:width` or `:height` is specified, we will return a picture whose width or height is closest to the requested size, respectively.
`info_fields`		Specify exactly which fields should be returned when getting the user's info. Value should be a comma-separated string as per <ref>https://developers.facebook.com/docs/graph-api/reference/user/</ref>
`locale`		Specify locale which should be used when getting the user's info. Value should be locale string as per <ref>https://developers.facebook.com/docs/reference/api/locale/</ref>
`auth_type`		Optionally specifies the requested authentication features as a comma-separated list <ref>https://developers.facebook.com/docs/facebook-login/reauthentication/</ref>. Valid values are `https` (checks for the presence of the secure cookie and asks for re-authentication if it is not present), and `reauthenticate` (asks the user to re-authenticate unconditionally). Default is `nil`.
`secure_image_url`	`false`	Set to `true` to use https for the avatar image url returned in the auth hash
`callback_url /` `callback_path`		Specify a custom callback URL used during the server-side flow. Note this must be allowed by your app configuration on Facebook

For example, to request email, user_birthday and read_stream permissions:

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :facebook, ENV['FACEBOOK_KEY'], ENV['FACEBOOK_SECRET'],
           :scope => 'email,user_birthday,read_stream'
end

OmniAuth GitHub

Install

To use GitHub OmniAuth Strateges<ref>https://github.com/intridea/omniauth-github</ref>, first, add this gem into your Gemfile, and then run bundle install:

gem 'omniauth-github'

Usage

Adding the middleware to a Rails app in config/initializers/omniauth.rb:

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :github, ENV['GITHUB_KEY'], ENV['GITHUB_SECRET']
end

Scopes

GitHub API v3 lets you set scopes to provide granular access to different types of data:

use OmniAuth::Builder do
  provider :github, ENV['GITHUB_KEY'], ENV['GITHUB_SECRET'], scope: "user,repo,gist"
end

More info is shown below:

Name	Description
`(no scope)`	Grants read-only access to public information (includes public user profile info, public repository info, and gists)
`user`	Grants read/write access to profile info only. Note that this scope includes `user:email` and `user:follow`
`user:email`	Grants read access to a user’s email addresses
`user:follow`	Grants access to follow or unfollow other users
`public_repo`	Grants read/write access to code, commit statuses, and deployment statuses for public repositories and organizations
`repo`	Grants read/write access to code, commit statuses, and deployment statuses for public and private repositories and organizations
`repo_deployment`	Grants access to deployment statuses for public and private repositories. This scope is only necessary to grant other users or services access to deployment statuses, without granting access to the code
`repo:status`	Grants read/write access to public and private repository commit statuses. This scope is only necessary to grant other users or services access to private repository commit statuses without granting access to the code
`delete_repo`	Grants access to delete adminable repositories
`notifications`	Grants read access to a user’s notifications. repo also provides this access
`gist`	Grants write access to gists
`read:repo_hook`	Grants read and ping access to hooks in public or private repositories
`write:repo_hook`	Grants read, write, and ping access to hooks in public or private repositories
`admin:repo_hook`	Grants read, write, ping, and delete access to hooks in public or private repositories
`admin:org_hook`	Grants read, write, ping, and delete access to organization hooks. Note: OAuth tokens will only be able to perform these actions on organization hooks which were created by the OAuth application. Personal access tokens will only be able to perform these actions on organization hooks created by a user
`read:org`	Read-only access to organization, teams, and membership
`write:org`	Publicize and unpublicize organization membership
`admin:org`	Fully manage organization, teams, and memberships
`read:public_key`	List and view details for public keys
`write:public_key`	Create, list, and view details for public keys
`admin:public_key`	Fully manage public keys

More Examples

References

CSC/ECE 517 Spring 2015/ch1b 21 QW

Contents

Background

Why Omniauth

Rack Middleware

Getting Start

Installing

Usage

Integrating OmniAuth into Rails Application

Logging

Other Examples

OmniAuth Facebook

Installing

Usage

Configuring

OmniAuth GitHub

Install

Usage

Scopes

More Examples

References

Navigation menu

CSC/ECE 517 Spring 2015/ch1b 21 QW

Background

Why Omniauth

Rack Middleware

Getting Start

Installing

Usage

Integrating OmniAuth into Rails Application

Logging

Other Examples

OmniAuth Facebook

Installing

Usage

Configuring

OmniAuth GitHub

Install

Usage

Scopes

More Examples

References

Navigation menu

Search