perf: reduce metrics labels (#1784)

Previously every new url will create a metrics entry with url as label. It will keep increasing as pod/ip creating and will not be released which will exhaust the memory. Aggregate the metrics by url prefix.

pkg/controller/client_go_adapter.go

@@ -21,6 +21,7 @@ package controller
 import (
 	"context"
 	"net/url"
+	"strings"
 	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
@@ -154,7 +155,12 @@ type latencyAdapter struct {
 }
 
 func (l *latencyAdapter) Observe(_ context.Context, verb string, u url.URL, latency time.Duration) {
-	l.metric.WithLabelValues(verb, u.String()).Observe(latency.Seconds())
+	url := u.String()
+	last := strings.LastIndex(url, "/")
+	if last != -1 {
+		url = url[:last]
+	}
+	l.metric.WithLabelValues(verb, url).Observe(latency.Seconds())
 }
 
 type resultAdapter struct {

pkg/daemon/metrics.go

@@ -3,6 +3,7 @@ package daemon
 import (
 	"context"
 	"net/url"
+	"strings"
 	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
@@ -170,7 +171,12 @@ type latencyAdapter struct {
 }
 
 func (l *latencyAdapter) Observe(_ context.Context, verb string, u url.URL, latency time.Duration) {
-	l.metric.WithLabelValues(verb, u.String()).Observe(latency.Seconds())
+	url := u.String()
+	last := strings.LastIndex(url, "/")
+	if last != -1 {
+		url = url[:last]
+	}
+	l.metric.WithLabelValues(verb, url).Observe(latency.Seconds())
 }
 
 type resultAdapter struct {