Ruby On Rails: Login
By Andres Aguiar
Sample Project
Download a sample project specific to this tutorial configured with your Auth0 API Keys.
- Ruby 2.3.1
- Rails 5.0.0
The first step in adding authentication to your Ruby on Rails application is to provide a way for your users to log in. The fastest, most secure, and most feature-rich way to do this with Auth0 is to use universal login.
Create an Application
Create a new application in your Auth0 dashboard and retrieve the Domain, Client ID and Client Secret for the app. The downloadable samples throughout the quickstart steps will be configured with the credentials for your default application.
Configure Callback URLs
A callback URL is a URL in your application where Auth0 redirects the user after they have authenticated.
You need to whitelist the callback URL for your app in the Allowed Callback URLs field in your Client Settings. If you do not set any callback URL, your users will see a mismatch error when they log in.
For security purposes, you must add the callback URL of your app to your Client Settings.
Your callback URL is currently set to:
https://YOUR_APP/callbackIn this case, the callbackURL should look something like:
https://example.com/auth/oauth2/callback
Install the Dependencies
To follow along with this guide, add the following dependencies to your Gemfile and run bundle install.
gem 'omniauth', '~> 1.6.1'
gem 'omniauth-auth0', '~> 2.0.0'
Initialize Omniauth Auth0
Create a file named auth0.rb under config/initializers and configure the OmniAuth middleware in it.
Rails.application.config.middleware.use OmniAuth::Builder do
provider(
:auth0,
'YOUR_CLIENT_ID',
'YOUR_CLIENT_SECRET',
'YOUR_AUTH0_DOMAIN',
callback_path: "/auth/oauth2/callback",
authorize_params: {
scope: 'openid profile',
audience: 'https://YOUR_AUTH0_DOMAIN/userinfo'
}
)
end
Add the Auth0 Callback Handler
Use the following command to create the controller that will handle the Auth0 callback:
rails generate controller auth0 callback failure --skip-template-engine --skip-assets
In the newly created controller, add a callback success and failure handler.
# app/controllers/auth0_controller.rb
class Auth0Controller < ApplicationController
def callback
# This stores all the user information that came from Auth0
# and the IdP
session[:userinfo] = request.env['omniauth.auth']
# Redirect to the URL you want after successful auth
redirect_to '/dashboard'
end
def failure
# show a failure page or redirect to an error page
@error_msg = request.params['message']
end
end
Replace the generated routes on routes.rb with the following:
get "/auth/oauth2/callback" => "auth0#callback"
get "/auth/failure" => "auth0#failure"
Trigger Login with Omniauth
Create a file called session_helper.rb:
# app/helpers/session_helper.rb
module SessionHelper
def get_state
state = SecureRandom.hex(24)
session['omniauth.state'] = state
state
end
end
Use the following command to create the controller that will handle user login:
rails generate controller home
In the controller home_controller.rb add the show action.
# app/controllers/home_controller.rb
class HomeController < ApplicationController
def show
end
end
Create a file called show.html.erb to add the template for show action. Add a link to /auth/auth0 to trigger user login.
<!-- app/views/home/show.html.erb -->
<section class="jumbotron text-center">
<h2><img class="jumbo-thumbnail" src="https://cdn.auth0.com/styleguide/1.0.0/img/badge.svg"></h2>
<h1>RoR Auth0 Sample</h1>
<p>Step 1 - Login.</p>
<a class="btn btn-success btn-lg" href="/auth/auth0">Login</a>
</section>
Check the User's Authentication Status
You can use a controller concern to control access to routes that require the user to be authenticated.
# app/controllers/concerns/secured.rb
module Secured
extend ActiveSupport::Concern
included do
before_action :logged_in_using_omniauth?
end
def logged_in_using_omniauth?
redirect_to '/' unless session[:userinfo].present?
end
end
Use the following command to create the controller for the dashboard view:
rails generate controller dashboard show --skip-template-engine --skip-assets
Include the concern in the newly-created controller to prevent unauthenticated users from accessing its routes:
# app/controllers/dashboard_controller.rb
class DashboardController < ApplicationController
include Secured
def show
end
end
Display Error Descriptions
Configure the application to display errors by adding the following to config/environments/production.rb:
OmniAuth.config.on_failure = Proc.new { |env|
message_key = env['omniauth.error.type']
error_description = Rack::Utils.escape(env['omniauth.error'].error_reason)
new_path = "#{env['SCRIPT_NAME']}#{OmniAuth.config.path_prefix}/failure?message=#{message_key}&error_description=#{error_description}"
Rack::Response.new(['302 Moved'], 302, 'Location' => new_path).finish
}
Troubleshooting
This error means that a cookie session is being used and because the whole profile is being stored, it overflows the max-size of 4 kb. If you are unable to access the user profile and you get an error similar to NoMethodError, undefined method '[]' for nil:NilClass, try using In-Memory store for development.
Go to /config/initializers/session_store.rb and add the following:
Rails.application.config.session_store :cache_store
Go to /config/environments/development.rb and add the following:
config.cachestore = :memorystore
It is recommended that a memory store such as MemCached being used for production applications.
SSL Issues
Under some configurations, Ruby may not be able to find certification authority certificates (CA certs).
Download the CA certs bundle to the project directory:
$ curl -o lib/ca-bundle.crt http://curl.haxx.se/ca/ca-bundle.crt
Add this initializer to config/initializers/fix_ssl.rb:
require 'open-uri'
require 'net/https'
module Net
class HTTP
alias_method :original_use_ssl=, :use_ssl=
def use_ssl=(flag)
path = ( Rails.env == "development") ? "lib/ca-bundle.crt" : "/usr/lib/ssl/certs/ca-certificates.crt"
self.ca_file = Rails.root.join(path).to_s
self.verify_mode = OpenSSL::SSL::VERIFY_PEER
self.original_use_ssl = flag
end
end
end
"failure message=invalid_credentials"
This issue doesn't occur when working locally but may happen in a staging or production environment. The error message may be displayed as:
omniauth: (auth0) Authentication failure! invalid_credentials: OAuth2::Error, server_error: The redirect URI is wrong. You send [wrong url], and we expected [callback url set in your app settings]
To solve this, add the following to config/environments/staging.rb or production.rb:
OmniAuth.config.full_host = "http://www.example.com"
Substitute http://www.example.com with the actual URL you'll be using in your application.