This page details the metrics that different Kubernetes components export. You can query the metrics endpoint for these components using an HTTP scrape, and fetch the current metrics data in Prometheus format.
Stable metrics observe strict API contracts and no labels can be added or removed from stable metrics during their lifetime.
Beta metrics observe a looser API contract than its stable counterparts. No labels can be removed from beta metrics during their lifetime, however, labels can be added while the metric is in the beta stage. This offers the assurance that beta metrics will honor existing dashboards and alerts, while allowing for amendments in the future.
Alpha metrics do not have any API guarantees. These metrics must be used at your own risk, subsequent versions of Kubernetes may remove these metrics altogether, or mutate the API in such a way that breaks existing dashboards and alerts.