How to make authorization on Ruby on Rails with Omniauth?

To implement a simple authorization using Omniauth in Ruby on Rails, follow these steps:

• Add dependencies to Gemfile
• Create GitHub app
• Create new file omniauth.rb
• Add button and route
• Create sessions

Add dependencies to Gemfile:

Open your Gemfile and add the following lines:

gem 'omniauth-github', github: 'omniauth/omniauth-github', branch: 'master'
gem "omniauth-rails_csrf_protection"

Save the Gemfile and run 'bundle install' to install the new gems.

Create GitHub app:

To use GitHub as the authentication provider, you need to create a GitHub app. Follow these steps:

• Go to your GitHub account settings.
• Navigate to "Developer Settings" and click on "OAuth Apps".
• Click on "New OAuth App" to create a new app.
• Fill in the required details, including your website's URL and the authorization callback URL. Use your website's URL with "/auth/github/callback" appended to it, instead of "localhost:3000" if you are deploying on production.

Save the app settings.

Create new file omniauth.rb:

In the 'config/initializers' folder, create a new file called 'omniauth.rb' and add the following code:

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

This code initializes the OmniAuth middleware and configures the GitHub provider with your client ID and client secret. Make sure to set the 'GITHUB_CLIENT_ID' and 'GITHUB_CLIENT_SECRET' environment variables in your application.

Add a button and route:

In your 'app/views/layouts/application.html.erb file', add the following line of code where you want the "Sign in with GitHub" button to appear:

<%= button_to 'Sign in with GitHub', '/auth/github', data: { turbo: false } %>

This code creates a button that will trigger the authentication process with GitHub when clicked.

Next, open the 'config/routes.rb' file and add the following line:

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

This route maps the callback URL to the 'create' action in the 'SessionsController'.

Create sessions:

Create a new file called 'sessions_controller.rb' in the 'app/controllers' folder and add the following code:

class SessionsController < ApplicationController
  def create
    auth_hash = request.env['omniauth.auth']
    print(auth_hash)
    redirect_to root_path
  end
end

This code defines the create action in the SessionsController. Inside the action, the auth_hash variable stores the authentication information returned by GitHub. You can process this information as needed. In this example, we print the auth_hash and then redirect the user to the root path.