Access URL fragment in Lambda Node.js function

Question

I have an S3 website that I'm trying to password-protect using a Lambda function and CloudFront. When a user tries to access the site, the Lambda function will redirect them to my Cognito login page, then redirect back to the site with a token.

When redirecting back, the access token is in the fragment (after "#"). Is it possible to obtain this token in the Lambda function using Node.js?

Answer 1

No, it isn't. The fragment is only available to JS running on the browser -- it's never sent to any web server.

There's an example here of one way to get it, as mentioned in Authorization@Edge – How to Use Lambda@Edge and JSON Web Tokens to Enhance Web Application Security, which uses Lambda@Edge rather than API Gateway (the two services have some overlapping functionality).