Duplicate User Entries Issue in Amazon Cognito

Question

We are using Amazon Cognito as our identity management solution for user registration and authentication. Our requirement is to ensure that each user is uniquely identified by their email address. However, we have noticed that when a user registers using their email, and subsequently registers again using social identity providers such as Google or Facebook, it creates duplicate entries in our user pool, causing data inconsistency.

Issue Description:
The problem arises when a user first registers with their email, and later decides to sign in using either Google or Facebook. Instead of updating the existing user entry with the new identity provider, a new user entry is created, leading to multiple accounts for the same email address.

Expected Behavior:
We expect Amazon Cognito to identify that the email address is already registered and update the user entry with the additional identity provider data, rather than creating a new entry.

Answer

Hi, to avoid this, customers usually us the Cognito pre-sign up trigger with a Lambda taking appropriate action based on requirements: https://docs.aws.amazon.com/cognito/latest/developerguide/user-pool-lambda-pre-sign-up.html

There is a good Github repo with sample code: https://github.com/vhalbuquerque/pre-signup-lambda

Best, Didier

There is a good Github  repo with sample code:  https://github.com/vhalbuquerque/pre-signup-lambda

Best,
Didier

Answer

Thank you for your response.
While your solution to preventing duplicate entries in Amazon Cognito is helpful, our specific requirement involves handling social identity provider logins and ensuring a single user entry with multiple linked identities.

We've identified that our issue arises when a user registers with their email and later signs in using social identity providers like Google or Facebook.

So how we can resolve this ?

Duplicate User Entries Issue in Amazon Cognito

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