add proxy metrics in app level

pkg/proxy/metrics/BUILD

@@ -0,0 +1,23 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["metrics.go"],
+    importpath = "k8s.io/kubernetes/pkg/proxy/metrics",
+    visibility = ["//visibility:public"],
+    deps = ["//vendor/github.com/prometheus/client_golang/prometheus:go_default_library"],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+    visibility = ["//visibility:public"],
+)

pkg/proxy/metrics/metrics.go

@@ -0,0 +1,52 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package metrics
+
+import (
+	"sync"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const kubeProxySubsystem = "kubeproxy"
+
+var (
+	// SyncProxyRulesLatency is the latency of one round of kube-proxy syncing proxy rules.
+	SyncProxyRulesLatency = prometheus.NewHistogram(
+		prometheus.HistogramOpts{
+			Subsystem: kubeProxySubsystem,
+			Name:      "sync_proxy_rules_latency_microseconds",
+			Help:      "SyncProxyRules latency",
+			Buckets:   prometheus.ExponentialBuckets(1000, 2, 15),
+		},
+	)
+)
+
+var registerMetricsOnce sync.Once
+
+// RegisterMetrics registers sync proxy rules latency metrics
+func RegisterMetrics() {
+	registerMetricsOnce.Do(func() {
+		prometheus.MustRegister(SyncProxyRulesLatency)
+	})
+}
+
+// SinceInMicroseconds gets the time since the specified start in microseconds.
+func SinceInMicroseconds(start time.Time) float64 {
+	return float64(time.Since(start).Nanoseconds() / time.Microsecond.Nanoseconds())
+}