Devise/Google OAuth 2: Not found. Authentication passthru

Question

I followed the tutorial in the readme of the omniauth-google-oauth2 gem and when I click the link on my root (@ pages#home), <%= link_to "Sign up with Google", user_google_oauth2_omniauth_authorize_path %>, I get the error:

Not found. Authentication passthru.

I've confirmed the ENV vars are there. I've been looking at similar topics with no luck. Any idea what I'm doing incorrectly?

In routes:

Rails.application.routes.draw do
      devise_for :users, controllers: { :omniauth_callbacks => "users/omniauth_callbacks" }

My omniauth_callbacks_controller is located at /controllers/users/omniauth_callbacks_controller.rb

class Users::OmniauthCallbacksController < Devise::OmniauthCallbacksController
  def google_oauth2
      # 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?
        flash[:notice] = I18n.t "devise.omniauth_callbacks.success", :kind => "Google"
        sign_in_and_redirect @user, :event => :authentication
      else
        session["devise.google_data"] = request.env["omniauth.auth"].except(:extra) #Removing extra as it can overflow some session stores
        redirect_to new_user_registration_url, alert: @user.errors.full_messages.join("\n")
      end
  end
end

In my devise.rb file:

config.omniauth :google_oauth2, ENV["GOOGLE_CLIENT_ID"], ENV["GOOGLE_CLIENT_SECRET"], {
      name: 'my-project',
      scope: 'email',
      prompt: 'select_account',
      image_aspect_ratio: 'original',
      image_size: 100,
      ssl_verify: false
  }

And in my User.rb:

devise :rememberable, :validatable, :omniauthable, :omniauth_providers => [:google_oauth2]

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

         # Uncomment the section below if you want users to be created if they don't exist
         # unless user
         #     user = User.create(name: data["name"],
         #        email: data["email"],
         #        password: Devise.friendly_token[0,20]
         #     )
         # end

         user
     end

Answer 1

I solved the problem adding the following to config/initializers/omniauth.rb:

OmniAuth.config.allowed_request_methods = %i[get]

Explanation:

the above is the configuration shown in https://github.com/zquestz/omniauth-google-oauth2#usage :

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :google_oauth2, ENV['GOOGLE_CLIENT_ID'], ENV['GOOGLE_CLIENT_SECRET']
end
OmniAuth.config.allowed_request_methods = %i[get]

but without

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

since that is already provided in your config/initializers/devise.rb:

  config.omniauth :google_oauth2, ENV["GOOGLE_CLIENT_ID"], ENV["GOOGLE_CLIENT_SECRET"], {
      name: 'my-project',
      scope: 'email',
      prompt: 'select_account',
      image_aspect_ratio: 'original',
      image_size: 100,
      ssl_verify: false
  }