feat: Add Prometheus Metrics

adds Prometheus Metrics support, improving monitoring and performance analysis.

Fix #50

cmd/localstorageplugin/main.go

@@ -18,11 +18,13 @@ package main
 
 import (
 	"flag"
+	"fmt"
 	"net/http"
 	"time"
 	// import pprof for performance diagnosed
 	_ "net/http/pprof"
 
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"k8s.io/klog/v2"
 
 	"github.com/caoyingjunz/csi-driver-localstorage/pkg/client/informers/externalversions"
@@ -42,6 +44,8 @@ var (
 	pprofPort   = flag.String("pprof-port", "6060", "The port of pprof to listen on")
 
 	kubeconfig = flag.String("kubeconfig", "", "Absolute path to the kubeconfig file. Needs to be set if the plugin is being run out of cluster.")
+
+	metricsPort = flag.Int("metricsport", 8080, "metrics port")
 )
 
 func init() {
@@ -77,6 +81,15 @@ func main() {
 	// set up signals so we handle the shutdown signal gracefully
 	ctx := signals.SetupSignalHandler()
 
+	// Start prometheus metrics
+	go func() {
+		klog.Infof("Listening for Prometheus metrics on port: %v", *metricsPort)
+		http.Handle("/metrics", promhttp.Handler())
+		if err := http.ListenAndServe(fmt.Sprintf(":%d", *metricsPort), nil); err != nil {
+			klog.Fatalf("Failed to initialize prometheus metrics, %v", err)
+		}
+	}()
+
 	kubeConfig, err := util.BuildClientConfig(*kubeconfig)
 	if err != nil {
 		klog.Fatalf("Failed to build kube config: %v", err)

go.mod

@@ -7,6 +7,7 @@ require (
 	github.com/golang/protobuf v1.5.3
 	github.com/google/uuid v1.3.0
 	github.com/imdario/mergo v0.3.15 // indirect
+	github.com/prometheus/client_golang v1.15.1
 	golang.org/x/net v0.8.0
 	google.golang.org/grpc v1.54.0
 	k8s.io/api v0.24.8