How to modify Google Cloud Pub/Sub subscription acknowledgement deadline for background Cloud Function

Question

When deploying a background Cloud Function for Cloud Pub/Sub via:

gcloud functions deploy function_name --runtime python37 --trigger-topic some_topic

A subscription gets automatically created with a push endpoint (likely App Engine standard endpoint, but those are claimed to be without the need of domain verification https://cloud.google.com/pubsub/docs/push#other-endpoints ).

For the generated subscription/endpoint there doesn't seem like a way to register/verify the domain ( https://www.google.com/webmasters/verification , https://console.cloud.google.com/apis/credentials/domainverification )

As a result the user cannot alter the subscription, for instance:

gcloud alpha pubsub subscriptions update some_subscription --ack-deadline=10

Would yield something like "INVALID_ARGUMENT: The supplied HTTP URL is not registered in the subscription's parent project"

Doing it via the web interface on GCP would also yield an error: "pubsub error INVALID_ARGUMENT"

Answer 1

When connecting to a Cloud Pub/Sub topic via Cloud Functions, a subscription is created on your behalf. This subscription is managed by Cloud Functions and therefore it is not possible to update the acknowledgement deadline.