Google Cloud Eventarc trigger not firing for Firestore (2nd Gen Cloud Function) in nam5

Google Cloud Serverless Applications
,
1

I’m trying to set up a bridge between Firestore and Cloud Run using a 2nd Gen Cloud Function and Pub/Sub, but the Cloud Function is not triggered when a new document is created.

The Setup:

  • Database: Firestore in nam5 (multi-region), (default) database.

  • Cloud Function: 2nd Gen, Python 3.12, located in us-central1.

  • Trigger: Eventarc (Provider: Cloud Firestore, Event: google.cloud.firestore.document.v1.created).

  • Trigger Region: nam5.

  • Filter: document: host_messages/{messageId}.

The Problem: When I create a document in host_messages collection (manually in the console or via app), no logs appear in the Cloud Function. It seems the event is never received by Eventarc.

What I’ve checked:

  1. IAM Roles: The Compute Engine default service account has Eventarc Event Receiver, Pub/Sub Publisher, and Cloud Run Invoker.

  2. Service Agent: I’ve granted roles/eventarc.eventReceiver to service-PROJECT_NUMBER@gcp-sa-firestore.iam.gserviceaccount.com.

  3. Path: I’ve tried both host_messages/{messageId} and the full resource path projects/MY_PROJECT/databases/(default)/documents/host_messages/{messageId}.

What am I missing to make Eventarc actually “see” the Firestore creation event in a multi-region setup?