Seeking decent documentation on creating a way to link a Google account with my app

Question

I'm trying to develop a react native application that won't require a user to sign into a bunch of different services every time. For now I'm trying to get the google side of things setup where a user can click a button which will allow me to link my application to there Google user account so that when they next visit the app the don't need to log into google for the functionality to continue to work.

I'm having a hard time finding documentation about how this link can be set up but I have found this page on Google which suggests it's possible.

https://myaccount.google.com/accountlinking?hl=en-GB&pli=1

The idea would be a bit like last.fm handles Spotify. a simple login and approve the service will mean that last.fm can listen to the Spotify account without requiring further auth every time its doing said functionality.

I can't find much in terms of tutorials or documentation on this specific thing.

Answer 1

Google OAuth and Scopes

It sounds like you're looking to implement Google identity federation in your app - specifically, OAuth 2.0. Google gives you quite a few options depending on the complexity of your authenticated user experience.

As for permissions, the Google API documentation calls these scopes . Here's a list of all the available scopes for every Google API. Setting scopes can take a few additional steps depending on which Google apps/information your app needs access to. By default, the Google API scopes for a new project are email , profile , and openid . Here's a video explaining how to view and modify the scopes in the Google API console(mentioned below).

1. Google Sign-in Button with scopes

The simplest method would be to follow this guide from Google which explains how to set up Google Auth on the frontend.

In short, you first set up a project within the Google API Console. Create a new project and take a look at your project scopes by clicking the Credentials tab, then the OAuth Consent Screen tab. Then back in your frontend code, include a script tag to call the Google API related to authentication functionality. Next, include a meta tag containing the client key found in the Google API Console. Then just create a sign in button with a certain class and data attribute(mentioned in the guide) and users should be able to sign in. This will return a small amount of user data in your code which you can use for validation within your app.

2. Firebase with scopes

A more complex solution would be Firebase authentication which returns even more user data, the use of a database to save and retrieve data related to the user and their session, and many other handy features that would normally be time consuming to develop. As such, Firebase is often called a backend as a service(BaaS).

To get the same level of granularity of scopes as the standard OAuth scenario outlined above, you may need to use a combination of the two as described in this article from Fireship.io .