I'm working on a ReactJS project and using Amplify for Signup/Signin. On signup, I have a post confirmation lambda trigger in Python that stores the user information (username, cognito id, etc.) in an on-prem database. I would like to also store the identity id, but I can't seem to find it in the event or context variable. I can find the identity id by calling Auth.currentCredentials() in React after the user has signed in, but would like to get this information during the signup process. 
Any help on this would be appreciated. Thank you.
You can save the identityId in a custom attribute
How to get Cognito Identity Id in Post Confirmation Lambda Trigger in Python using Amplify React?