IssueTracker

Currently, there is a hard limit to the number of pubsub topics per project https://cloud.google.com/pubsub/quotas#resource_limits. This information isn't programmatically accessible from what I could see. It would be nice to expose a metric for tracking the quota so we can alert on it, feed it into datadog, and ensure our development operations don't come to a standstill. As of now, we have to rely on proxy metrics (review app count) which isn't ideal because the number of topics/subscriptions per review app changes frequently.

gcloud alpha services quota list \
    --service=pubsub.googleapis.com \
    --consumer=projects/<my_project>

---
consumerQuotaLimits:
- metric: pubsub.googleapis.com/projecttopics
  quotaBuckets:
  - defaultLimit: '10000'
    dimensions:
      project: <project_id>
    effectiveLimit: '10000'
displayName: Topics per project
metric: pubsub.googleapis.com/projecttopics
unit: '1'

Seems like a reasonable enhancement to the api. The same could be implemented for subscriptions as well.

In the docs these are listed as resource_limits so maybe the ask is broader and involves creating metrics around per project resource limits.