Decouple shared functions between controllers (#8829)

* Decouple shared functions between controllers

* Apply suggestions from code review

Co-authored-by: Jintao Zhang <tao12345666333@163.com>

* Fix package names and fmt

Co-authored-by: Jintao Zhang <tao12345666333@163.com>

pkg/metrics/handler.go

@@ -0,0 +1,87 @@
+/*
+Copyright 2022 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 (
+	"fmt"
+	"net/http"
+	"net/http/pprof"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"k8s.io/apiserver/pkg/server/healthz"
+	klog "k8s.io/klog/v2"
+)
+
+func RegisterHealthz(healthPath string, mux *http.ServeMux, checks ...healthz.HealthChecker) {
+
+	healthCheck := []healthz.HealthChecker{healthz.PingHealthz}
+	if len(checks) > 0 {
+		healthCheck = append(healthCheck, checks...)
+	}
+	// expose health check endpoint (/healthz)
+	healthz.InstallPathHandler(mux,
+		healthPath,
+		healthCheck...,
+	)
+}
+
+func RegisterMetrics(reg *prometheus.Registry, mux *http.ServeMux) {
+	mux.Handle(
+		"/metrics",
+		promhttp.InstrumentMetricHandler(
+			reg,
+			promhttp.HandlerFor(reg, promhttp.HandlerOpts{}),
+		),
+	)
+}
+
+func RegisterProfiler(host string, port int) {
+	mux := http.NewServeMux()
+
+	mux.HandleFunc("/debug/pprof/", pprof.Index)
+	mux.HandleFunc("/debug/pprof/heap", pprof.Index)
+	mux.HandleFunc("/debug/pprof/mutex", pprof.Index)
+	mux.HandleFunc("/debug/pprof/goroutine", pprof.Index)
+	mux.HandleFunc("/debug/pprof/threadcreate", pprof.Index)
+	mux.HandleFunc("/debug/pprof/block", pprof.Index)
+	mux.HandleFunc("/debug/pprof/cmdline", pprof.Cmdline)
+	mux.HandleFunc("/debug/pprof/profile", pprof.Profile)
+	mux.HandleFunc("/debug/pprof/symbol", pprof.Symbol)
+	mux.HandleFunc("/debug/pprof/trace", pprof.Trace)
+
+	server := &http.Server{
+		Addr: fmt.Sprintf("%s:%d", host, port),
+		//G112 (CWE-400): Potential Slowloris Attack
+		ReadHeaderTimeout: 10 * time.Second,
+		Handler:           mux,
+	}
+	klog.Fatal(server.ListenAndServe())
+}
+
+func StartHTTPServer(host string, port int, mux *http.ServeMux) {
+	server := &http.Server{
+		Addr:              fmt.Sprintf("%s:%v", host, port),
+		Handler:           mux,
+		ReadTimeout:       10 * time.Second,
+		ReadHeaderTimeout: 10 * time.Second,
+		WriteTimeout:      300 * time.Second,
+		IdleTimeout:       120 * time.Second,
+	}
+	klog.Fatal(server.ListenAndServe())
+}