Google plus API shutdown today, which alternative can be used to authentication?

Solution 1:

Finally, I somehow managed to solve the issue by providing an alternate OpenIdConnect endpoint for user information. Using source, I replaced:

https://www.googleapis.com/plus/v1/people/me/openIdConnect

with:

https://www.googleapis.com/oauth2/v3/userinfo

I monkey-patched omniauth-google-oauth2 as follows:

config/initializers/omniauth_google_oauth2_patch.rb

class OmniAuth::Strategies::GoogleOauth2 < OmniAuth::Strategies::OAuth2
  def raw_info
    @raw_info ||= access_token.get('https://www.googleapis.com/oauth2/v3/userinfo').parsed
  end
end

And it's working great now.