hosts: add hostsfile as label for coredns_hosts_entries (#6801)

Signed-off-by: Paco Xu <paco.xu@daocloud.io>

plugin/hosts/hostsfile.go

@@ -138,7 +138,7 @@ func (h *Hostsfile) readHosts() {
 	h.mtime = stat.ModTime()
 	h.size = stat.Size()
 
-	hostsEntries.WithLabelValues().Set(float64(h.inline.Len() + h.hmap.Len()))
+	hostsEntries.WithLabelValues(h.path).Set(float64(h.inline.Len() + h.hmap.Len()))
 	hostsReloadTime.Set(float64(stat.ModTime().UnixNano()) / 1e9)
 	h.Unlock()
 }

plugin/hosts/metrics.go

@@ -14,7 +14,7 @@ var (
 		Subsystem: "hosts",
 		Name:      "entries",
 		Help:      "The combined number of entries in hosts and Corefile.",
-	}, []string{})
+	}, []string{"hostsfile"})
 	// hostsReloadTime is the timestamp of the last reload of hosts file.
 	hostsReloadTime = promauto.NewGauge(prometheus.GaugeOpts{
 		Namespace: plugin.Namespace,