Google/Facebook OAuth2 in Rails Front-end app with rails-api as webservice

Question

I have my front-end rails app that uses AngularJs too and I also have an api backend also written in Rails (used rails-api gem). I have implemented login system for this system. Now I want to implement login with facebook/google. I have searched through internet and so far I found this blog. From this blog, I got the idea of implementing google OAuth 2 in Android with Rails as backend. But In my case I want to implement google OAuth 2 in my front-end app (Rails + Angular) with Rails as backend.

For implementation of google OAuth 2, Front-end app need to request the token to google oauth2 authorization server and I have no idea on how to do it.

Also, Is it good to use rails for requesting the token or I can use Angular for that part. What would be the best practice for this purpose?

Answer 1

First, you need to implement the google login in front-end. Here is google documentation on implementing google sign-in in javascript. google will provide you with information on user's profile. After you got the information, you can send it to you service. On server side/Backend you can do whatever with this information. That's on you.

Additionally, this documentation might be helpful for your case.

Answer 2

You could use omniauth-google-oauth2 gem

Main idea is to implement this into Devise.

Good solution You could find this.

With this solution, it is no problem if You use frontend/backend. So, You should pay attention on next steps:

User Model:

devise :database_authenticatable, ... , :omniauthable

Devise.rb:

config.omniauth :google_oauth2, ENV['GP_key'], ENV['GP_secret'],
    {
                  name: 'google',
                  scope: 'plus.login, userinfo.email, userinfo.profile,
                          ...
                          youtubepartner, youtubepartner-channel-audit',
                  prompt: "select_account"
    }

Next steps as in solutions..

In my project it is workable with frontend/backend too. So, if you find difficulties, I will be glad do advice for it solving...

Update: for Android versions of frontend. You should not do authentication/authorization frontend on Google. You should do it on backend side. You could use webtools or other suitable ways for walking around Devise and Google auth pages...