Expand description
Cloud Monitoring backlog-depth read.
ONE light, low-frequency, batched read of
subscription/num_undelivered_messages across the project’s subscriptions,
mapped back to queue types. Feeds BOTH the queue_depth gauge and the
health-endpoint depth. Any failure (or the emulator, which serves no Cloud
Monitoring) yields “unavailable” — never a hardcoded 0. Requires ADC with
roles/monitoring.viewer.