Using Omniauth github to login and restricting depending on the organization

First you need to create your personal Api and developer application in the follow url in github.com site:

https://github.com/settings/applications

restricting github organization

The gems required in Gemfile:

gem 'omniauth-github'
gem 'httparty'

config/initializers/omniauth.rb

API_CONFIG = YAML.load_file("#{Rails.root}/config/api_config.yml")[Rails.env]
Rails.application.config.middleware.use OmniAuth::Builder do
  provider :developer unless Rails.env.production?
  provider :github, API_CONFIG['key'], API_CONFIG['token']
end

The fileconfig/api_config.yml and its content:

github_key: &github_key
  token: ENV['token']
  key: ENV['key']
  organization: hackd
staging:<
  <<: *github_key
development:
  <<: *github_key
production:
  <<: *github_key
test:
  <<: *github_key
&#91;/ruby&#93;

the file app/controllers/sessions_controller.rb
the content:

&#91;ruby&#93;
require 'net/http'
class SessionsController < ApplicationController
  def new
  end
  def create
    reset_session # see http://guides.rubyonrails.org/security.html#session-fixation
    info = request.env&#91;"omniauth.auth"&#93;
    belongs_to_organization? info&#91;"credentials"&#93;&#91;"token"&#93;
    session&#91;:name&#93; = info&#91;"info"&#93;&#91;"name"&#93; || info&#91;"info"&#93;&#91;"email"&#93; || info&#91;"info"&#93;&#91;"nickname"&#93; || "fellow Ruby on Rails enthusiast"
    redirect_to events_path, :notice => "Welcome #{session[:name]}!"
  end

  def failure
    redirect_to login_url, :alert => 'Sorry, there was something wrong with your login attempt. Please try again.'
  end

  def destroy
    reset_session
    flash[:notice] = "Logged out."
    redirect_to events_path
  end

  private
  def belongs_to_organization? token
    url = "https://api.github.com/user/orgs?access_token=#{token}"
    @organizations = HTTParty.get(url)
    @organizations.map!{|x| x["login"]}.include? API_CONFIG['organization']
  end
end