Cloud Functions returns 403 error also with Cloud Functions Invoker permissions

Question

Within GCP:

1. I created a function in Google Cloud Functions.
2. I want to invoke that function from Google Workflows.
3. I added a service account with "Cloud Functions Invoker" permissions.
4. I created a workflow in Google Workflows, it uses the service account with "Cloud Functions Invoker" permissions that I added before.
5. I run the workflow... it fails with "HTTP server responded with error code 403".

Why does it give 403 error if I'm using a service account with "Cloud Functions Invoker" permissions? If I disable authentication for the function it works, but I need authentication because it's not a public API.

Answer 1

This must be added in the workflow code:

auth:
    type: OIDC

See https://cloud.google.com/workflows/docs/calling-run-functions?authuser=1#add_auth_info