Since Prometheus only pulls metrics from endpoints it knows, we have to explicitly tell it where we'd like to collect data from. Under the path /config is the page that lists current configured targets to pull. By default, there would be one job that collects the current metrics about Prometheus itself, and it's in the conventional scraping path, /metrics. We would see a very long text page if connecting to the endpoint:
$ kubectl exec -n monitoring prometheus-1496092314-jctr6 -- \ wget -qO - localhost:9090/metrics # HELP go_gc_duration_seconds A summary of the GC invocation durations. # TYPE go_gc_duration_seconds summary go_gc_duration_seconds{quantile="0"} 2.4032e-05 go_gc_duration_seconds{quantile="0.25"} ...
