I currently have a React app hosted in Cloud Run behind an IAP which is working great. I would like to add support for the React app to upload files to a Google Cloud Storage Bucket. I would like to leverage the already authenticated user via the IAP login to automatically authenticate the GCS client library and enforce permissions via GCP IAM policies. My question is how to get the auth token from the JavaScript React app to authenticate the GCS client library? I see a cookie is set via IAP but it’s an http only cookie and thus cannot be accessed via JavaScript.