AWS Amplify - how to get “Cognito Identity Id” from Cognito

There appears to be two different ids that identify users in an AWS Amplify project that uses AWS Cognito:

• “Cognito Identity Id” and…
• “Cognito Sub”

Is there any way to get a “Cognito Identity Id” purely from Cognito itself, using the CognitoIdentityServiceProvider? For example, if a new user is created programmatically and there’s an associated table indexed on their “cognito identity id” and I want to set values in that table before the user logs in. It seems like it is only exposed in requests by that actual user.

For more context on what I understand these terms to be:

1. Cognito Identity Id

   • Is this the id from the identity pool?
   • This is a uuid with the region prefixed, e.g.,: "us-east-1:12345678-beef-cafe-face-1234567890ab"
   • Accessed via:
     • In frontend code with the Auth module: Auth.currentUserInfo().then(user => user.id)
     • In backend API requests for an authenticated user: req.apiGateway.event.requestContext.identity.cognitoIdentityId
     • Not available in the results of: new AWS.CognitoIdentityServiceProvider().listUsers(params)
   • Notes:
     • This id is treated as a "userId" in various Amplify examples/docs
     • I’ve seen examples of people saving this manually in Cognito with a custom parameter of "custom:identity_id", which can only be set during an authenticated request by that user

2. Cognito Sub

   • This appears to be something like a unique id for the user pool?
   • This is a uuid
   • Accessed via:
     • In frontend code with the Auth module: Auth.currentUserInfo().then(user => user.attributes.sub)
     • In backend API requests for an authenticated user: req.apiGateway.event.requestContext.identity.cognitoAuthenticationProvider.match(/CognitoSignIn:([^:]+)$/)[1]
     • In the results of CognitoIdentityServiceProvider queries