There is an Prometheus exporter that is on by default that enables you to configure a Prometheus compatible scraper to grab data from the various Vitess components. All Vitess components export their metrics on their http port at /metrics.

If your Vitess configuration includes running the Vitess Operator on Kubernetes, then you can have Prometheus or a Prometheus compatible agent running in your Kubernetes cluster. This would then scrape the metrics from Vitess automatically, as it would be run on the ports advertised and on our standard /metrics page.

You can read more about getting the metrics into Prometheus here.