Cognito User Pool : callback URL for Android Serverless app

Hi,

I'd say the point is how to manage the authentication process. Amazon Cognito user pools can help you implement Social sign-in, for example using Google, but still there have to be integrations running at the back-end. One of those integration is actually between Amazon Cognito and the Identity Provider (IdP) which is Google in this case.

You can take a look at https://docs.aws.amazon.com/cognito/latest/developerguide/authentication.html that explains “Your app users can sign in either directly through a user pool, or federate through a third-party identity provider (IdP). The user pool manages the overhead of handling the tokens that are returned from social sign-in through Facebook, Google, Amazon, and Apple, and from OpenID Connect (OIDC) and SAML IdPs. After successful authentication, Amazon Cognito returns user pool tokens to your app. You can use the tokens to grant your users access to your own server-side resources, or to the Amazon API Gateway.”

Another option that you could evaluate is Amazon Cognito identity pools (federated identities), instead of Amazon Cognito user pools. These are a couple of references that might help. Pay particular attention to the second link wiht the authentication flow.

https://docs.aws.amazon.com/cognito/latest/developerguide/getting-started-with-identity-pools.html

https://docs.aws.amazon.com/cognito/latest/developerguide/authentication-flow.html

Of course, there are always trade-offs, pros and cons.

I hope this helped and good luck!!!