Rails - OmniAuth/OAuth

Add gems

bundle add omniauth
bundle add omniauth-oauth2
bundle add omniauth_openid_connect

optional: bundle add omniauth-rails_csrf_protection

Configure Devise

config.omniauth :google_oauth2, Rails.application.credentials.google&.dig("oauth_client_id"), Rails.application.credentials.google&.dig("oauth_client_secret"), {}

DO NOT CONFIGURE the omni_auth initializer ONLY use it for the post or get request setting.

Generate views

rails generate devise:views

Add database colums to user model

rails g migration AddColumnsToUsers provider uid

Migrate db

rails db:migrate

Controller method

In app/controllers/users/omniauth_callbacks_controller.rb

  def zitadel
    # You need to implement the method below in your model (e.g. app/models/user.rb)
    @user = User.from_omniauth(request.env["omniauth.auth"])

    if @user.persisted?
      sign_in_and_redirect @user, event: :authentication
      set_flash_message(:notice, :success, kind: "ZITADEL") if is_navigational_format?
    else
      session["devise.zitadel_data"] = request.env["omniauth.auth"]
      redirect_to new_user_registration_url
    end
  end

  def failure
    redirect_to root_path
  end

User model

...
:omniauthable, omniauth_providers: [:google_oauth2]

  def self.from_omniauth(access_token)
    data = access_token.info
    user = User.where(email: data['email']).first

    return user if user

    User.create(name: data['name'],
                email: data['email'],
                admin: data['email'].split("@").last.downcase == 'domain.nl',
                password: Devise.friendly_token[0, 30])
  end

<%= form_tag user_google_oauth2_omniauth_authorize_path, method: :post do %>
  <%= button_tag "Sign in with Google", type: "submit", data: { turbo: "false" }, class: "hoi" %>
<% end %>

Redirect_url and Redirect_uri

it is better to use 127.0.0.1 than localhost as a redirect url
it is better to use https in development for the redirect url