AWS API Gateway / Cognito Userpools / Lambdas not able to pass caller credentials

Question

I'm working on an AWS API Gateway implementation with a Lambda backend. I use the API Gateway integration with the Cognito Userpools (fairly new) instead of building a custom authorizer using Lambda (which was the recommended way before it was integrated).

I've created a proof of concept (javascript) that authenticates a user with Cognito and then makes a call to the API Gateway with those credentials. So, basically, the end call to the API Gateway is with the JWT token that I received from Cognito (result.idToken.jwtToken) in the Authorization header. This all works and I can validate that only with this token you can access the API.

All working fine, but now I want to get access to the Cognito identity in my Lambda; for instance the identy id or the name or email. I have read how to map all the parameters, but I'm actually just using the standard 'Method Request Passthrough' template in the integration request. I log all the parameters in the lambda and all the 'cognito' parameters are empty.

I've looked through many similar questions and they all propose to enable the 'Invoke with caller credentials' checkbox on the integration request. That makes perfect sense.

However, this checkbox can only be enabled if you are using AWS_IAM as authorization and not if you have selected your cognito UserPool. So it is just not possible to select it and is actually disabled.

Does anybody know what to do in this case? Is this still work in progress, or is there a reason why you can't enable this and get the cognito credentials in your Lambda?

Many thanks.

Answer 1

If you need to log the user information in your backend, you can use $context.authorizer.claims.sub and $context.authorizer.claims.email to get the sub and email for your Cognito user pool.

Here is the documentation about Use Amazon Cognito Your User Pool in API Gateway