Google Authentication Strategy for Rails 5 Application

When creating my rails final project, WINELOG, I found it difficult to implement social login with Google. I also found there was a lack of recent documentation or blog posts on the subject.

Here’s a quick guide on how to set up Google log in.

Create app in Google Developers Console. Select credentials, then ‘create credentials’, and select ‘Create OAuth client ID’, then select ‘web application’.

Here you’ll be able to see the client ID and client secret - you’ll need those soon!

Add in the authorized redirect URIs - http://localhost:3000/auth/google_oauth2/callback works for testing in the rails server, but remember to add the URI for the production well.

Add necessary gems to your gem file. You’ll need to add three gems - gem 'omniauth', gem 'dotenv-rails' and gem 'omniauth-google-oauth2'. Run bundle in the terminal.

Create a .env file in the root directory of your app. Add the following code to the file - and remeber to add this file to your gitignore.

GOOGLE_CLIENT_ID=Your client id
GOOGLE_CLIENT_SECRET=Your client secret

Add omniauth.rb to /config/initializers with this code:

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :google_oauth2, ENV["GOOGLE_CLIENT_ID"],ENV["GOOGLE_CLIENT_SECRET"], skip_jwt: true
end

Add callback route to routes.rb. get '/auth/:provider/callback' => 'sessions#omniauth'

Add class method to user model. You’ll use this method in the sessions controller. This is a good spot to put a binding.pry to inspect the auth hash - you can map the data to your User model however you would like; this is a very simple example.

  def self.from_omniauth(auth)
    where(email: auth.info.email).first_or_initialize do |user|
      user.user_name = auth.info.name
      user.email = auth.info.email
      user.password = SecureRandom.hex
    end
  end

Add methods to sessions controller. You’ll need two methods in the sessions controller - one to create (or log in) a user via Google, and a private method to request the auth hash.

def omniauth
    @user = User.from_omniauth(auth)
    @user.save
    session[:user_id] = @user.id
    redirect_to home_path
  end

  private

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

Add login/signup links. You’ll need to add this link anyplace you want a user to be able to log in or sign up. It can be styled as a button or not, and does not need to be inside a form. <%= link_to "Log In with Google", '/auth/google_oauth2' %>

That should have everything up and running! You can view the full repository for WINELOG here.