The Google Cloud Pub/Sub API exports usage metrics that can be monitored programmatically or accessed via Stackdriver Monitoring. You can create dashboards, set up alerts, and set up an autoscaler to manage publisher or message processing (subscriber) instances running on Compute Engine. Note that while Google Cloud Pub/Sub itself is scaled automatically, you are responsible for managing your Pub/Sub quota.
Monitor your resources on the go
Get the Google Cloud Console app to help you manage your projects.