Demo app for boston.rb project night #5 OmniAuth demo
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Readme.md

Authentication with OmniAuth

Basic Demo

Demo Goals

Auth Options

Local Faves

OmniAuth?

"OmniAuth is a Ruby authentication framework aimed to abstract away the difficulties of working with various types of authentication providers. It is meant to be hooked up to just about any system, from social networks to enterprise systems to simple username and password authentication."

  • Implemented using a base gem, and pluggable strategies.
  • Each strategy is a different gem.
  • Does not provide user models, or other convenience methods (e.g. logged_in?, current_user)
  • Works with Devise, CanCan, etc.

Create Project, Install OmniAuth & Identity

rails new Project

Add to Gemfile and bundle:

gem 'bcrypt-ruby', '~> 3.0.0'

gem 'omniauth'

gem 'omniauth-identity'

Now add the rack middleware and options in an initializer. You can specify what fields to care about, and these show up in the default form.

config/initializers/omniauth.rb:

Rails.application.config.middleware.use OmniAuth::Builder do
	provider :identity, :fields => [:name, :email]
end

Identity Model

OmniAuth::Identity is implemented like an external provider, but it is resident in your app. Stores email, hashed password, and potentially other info in a model (many persistence options).

Make an Identity model:

rails g model identity email:string password_digest:string

Update Identity model to inherit from:

OmniAuth::Identity::Models::ActiveRecord

Add attribute access (this is wrong on the identity gem docs):

attr_accessible :email, :password, :password_confirmation

OmniAuth uses the /auth/:provider path as the link to follow to start the authentication process for a provider.

Can test by going to http://localhost:3000/auth/identity/register

Sessions

Need a sessions controller and actions for new, create, destroy, failure:

rails g controller Sessions new create destroy failure

Session new page that links to: /auth/identity/register

After you register, tries to take you to a strategy specific callback: /auth/identity/callback

routes.rb:

match '/auth/:provider/callback', :to => 'sessions#create'
match '/auth/failure', :to => 'sessions#failure'
match '/logout', :to => 'sessions#destroy', :as => 'logout'

root :to => 'sessions#new'

This is a bit sneaky: sessions#create method for all providers, but could have done one per provider, if that would have helped.

Also - when there is an error - a rack var has the login info:

def new
	@identity = env['omniauth.identity']
end

Users and Authentications

It's a good practice to have a many-to-one relationship between User and Auhentications.

Devise works this way with OmniAuth, and it makes sense with the goal of one Users with many external identities.

An authentication has the relationship to the user, the name/identifier of the provider, and the UID for the user from thaty provider. This works for the identity strategy, and external strategies (e.g. {user_id:[user.id], provider:'identity', oid:[identity.id]}):

rails g model authentication user_id:integer provider:string uid:string

Users should be about the person, and have info about them as domain objects with biz rules, not about how they login to some site:

rails g model user name:string

Now we need to implement creating the authentication, user, and logging in.

We will implement it to work for identity, but should be very similar to how it works for other providers. The major difference should be in what data comes back from the provider, and how that is used to fill out the models.

Some login basics (if you aren't using Devise, for example):

application_controller.rb

class ApplicationController < ActionController::Base
	protect_from_forgery
	helper_method :current_user, :logged_in?

	private
	def current_user
		@current_user ||= User.find(session[:user_id]) if session[:user_id]
	end

	def current_user=(user)
		session[:user_id] = user.id
		@current_user = user
	end

	def logged_in?
		!!current_user
	end
end

Show when we are logged in

app/views/sessions/new.erb:

<div>
<% if logged_in? %>

	<b><%= current_user.name %></b> is logged in.

<% else %>
	...
<% end %>
</div>

Finding or Creating Users/Authentications

sessions_controller.rb:

def create
	auth_hash = request.env['omniauth.auth']
	authentication = Authentication.find_or_create_from_auth_hash(auth_hash)
	self.current_user = authentication.user
	redirect_to root_url, :notice => "Logged in successfully."
end

The 'omniauth.auth' hash, set by omniauth rack middleware, has the info returned from a succssful authentication.

  • auth_hash['provider'] is set to the string name of the provider

  • auth_hash['uid'] is set to some unique id for the user scoped by the provider

Other hashes are usually included, but vary by provider and strategy implementation.

  • auth_hash['info'] typically has basic user info (login, email)

  • auth_hash['extra'] can include this as well, or used for extended profile info

  • auth_hash['credentials'] typically has an access token and expiry for OAuth2 providers

Use these in the models to find/create the Authentication & User.

authentication.rb

def self.find_or_create_from_auth_hash(auth_hash)
	auth = find_by_provider_and_uid(auth_hash['provider'], auth_hash['uid'].to_s)
	unless auth
		user = User.find_or_create_from_auth_hash(auth_hash)

		auth_create_attributes = {
			:provider   => auth_hash['provider'],
			:uid        => auth_hash['uid']
		}
		
		auth = user.authentications.create!(auth_create_attributes)
	end
	auth
end

user.rb

def self.find_or_create_from_auth_hash(auth_hash)
	info = auth_hash['info']
	name = info['name'] || info['email']
	find_or_create_by_name(name)
end

Adding another provider: omniauth-github

Here is the gem: https://github.com/intridea/omniauth-github

For oauth, nice to be deployed to register an app, so I have the demo app on heroku:

http://omniauthdemo.herokuapp.com/

Add the strategy gem and bundle:

gem 'omniauth-github'

Add it to the config/init

provider :github, ENV['GITHUB_KEY'], ENV['GITHUB_SECRET'], :scope => 'user,repo,gist'

Now go create an app on github, and get the key and secret: https://github.com/settings/applications

Set these in your local env, and on heroku:

.rvmrc (or equivalent)

export GITHUB_KEY=abcdefghijklmnop
export GITHUB_SECRET=abcdefghijklmnopabcdefghijklmnopabcdefghijklmnop

heroku cmd line:

heroku config:add GITHUB_KEY=abcdefghijklmnop
heroku config:add GITHUB_SECRET=abcdefghijklmnopabcdefghijklmnopabcdefghijklmnop

Add a link to github from the sessions#new page:

<h3>External Providers</h3>
<p><%= link_to "login", "/auth/github" %> with github.</p>

That ought to do it - pretty much everything else we wrote carries over!

FYI - I temporarily logged the auth_hash, to give a sense of what is in there:

	--- !map:OmniAuth::AuthHash 
	provider: github
	uid: "46439"
	info: !map:OmniAuth::AuthHash::InfoHash 
		nickname: kookster
		email: andrew_AT_beginsinwonder_DOT_com
		name: Andrew Kuklewicz
		image: https://secure.gravatar.com/avatar/abcdefghiklmnopqrstuvwxyz?d=https://a248.e.akamai.net/assets.github.com%2Fimages%2Fgravatars%2Fgravatar-user-420.png
		urls: !map:Hashie::Mash 
			GitHub: https://github.com/kookster
			Blog: http://beginsinwonder.com
	credentials: !map:Hashie::Mash 
		token: abcdefghiklmnopqrstuvwxyz
		expires: false
	extra: !map:Hashie::Mash 
		raw_info: !map:Hashie::Mash 
			type: User
			login: kookster
			owned_private_repos: 0
			followers: 11
			created_at: "2009-01-14T06:39:27Z"
			company: http://www.prx.org
			email: andrew_AT_beginsinwonder_DOT_com
			disk_usage: 59516
			plan: !map:Hashie::Mash 
				private_repos: 0
				space: 307200
				name: free
				collaborators: 0
			public_gists: 1
			blog: http://beginsinwonder.com
			hireable: false
			avatar_url: https://secure.gravatar.com/avatar/abcdefghiklmnopqrstuvwxyz?d=https://a248.e.akamai.net/assets.github.com%2Fimages%2Fgravatars%2Fgravatar-user-420.png
			private_gists: 0
			following: 8
			html_url: https://github.com/kookster
			name: Andrew Kuklewicz
			bio: Tech Dir @ prx.org
			collaborators: 0
			public_repos: 10
			id: 46439
			total_private_repos: 0
			location: Boston, MA
			url: https://api.github.com/users/kookster
			gravatar_id: abcdefghiklmnopqrstuvwxyz

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