Since a same metric can be exposed by more than one metric server, it would be useful to expose a debug API to let the user understand which metric server is used to serve a given metric.

This new API should be protected by an authentication mechanism and support TLS, like the other ones used to serve the custom metrics API.

GET /apis/explain/container_cpu_cfs_periods_total

{
	"name": "container_cpu_cfs_periods_total",
	"metricSources": [{
		...
	}, {
		...
	}]
}