Refactor metrics

Move common boilerplate code under pkg/utils.

pkg/nfd-master/metrics.go

@@ -17,12 +17,7 @@ limitations under the License.
 package nfdmaster
 
 import (
-	"fmt"
-	"net/http"
-
 	"github.com/prometheus/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/promhttp"
-	"k8s.io/klog/v2"
 	"sigs.k8s.io/node-feature-discovery/pkg/version"
 )
 
@@ -40,8 +35,6 @@ const (
 )
 
 var (
-	srv *http.Server
-
 	buildInfo = prometheus.NewGauge(prometheus.GaugeOpts{
 		Name: buildInfoQuery,
 		Help: "Version from which Node Feature Discovery was built.",
@@ -94,33 +87,3 @@ var (
 func registerVersion(version string) {
 	buildInfo.SetToCurrentTime()
 }
-
-// runMetricsServer starts a http server to expose metrics
-func runMetricsServer(port int) {
-	r := prometheus.NewRegistry()
-	r.MustRegister(
-		buildInfo,
-		nodeUpdateRequests,
-		nodeUpdates,
-		nodeUpdateFailures,
-		nodeLabelsRejected,
-		nodeERsRejected,
-		nodeTaintsRejected,
-		nfrProcessingTime,
-		nfrProcessingErrors)
-
-	mux := http.NewServeMux()
-	mux.Handle("/metrics", promhttp.HandlerFor(r, promhttp.HandlerOpts{}))
-
-	klog.InfoS("metrics server starting", "port", port)
-	srv = &http.Server{Addr: fmt.Sprintf(":%d", port), Handler: mux}
-	klog.InfoS("metrics server stopped", "exitCode", srv.ListenAndServe())
-}
-
-// stopMetricsServer stops the metrics server
-func stopMetricsServer() {
-	if srv != nil {
-		klog.InfoS("stopping metrics server", "port", srv.Addr)
-		srv.Close()
-	}
-}

pkg/nfd-master/nfd-master.go

@@ -250,9 +250,19 @@ func (m *nfdMaster) Run() error {
 
 	// Register to metrics server
 	if m.args.MetricsPort > 0 {
-		go runMetricsServer(m.args.MetricsPort)
+		m := utils.CreateMetricsServer(m.args.MetricsPort,
+			buildInfo,
+			nodeUpdateRequests,
+			nodeUpdates,
+			nodeUpdateFailures,
+			nodeLabelsRejected,
+			nodeERsRejected,
+			nodeTaintsRejected,
+			nfrProcessingTime,
+			nfrProcessingErrors)
+		go m.Run()
 		registerVersion(version.Get())
-		defer stopMetricsServer()
+		defer m.Stop()
 	}
 
 	// Run gRPC server

pkg/nfd-topology-updater/metrics.go

@@ -17,12 +17,7 @@ limitations under the License.
 package nfdtopologyupdater
 
 import (
-	"fmt"
-	"net/http"
-
 	"github.com/prometheus/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/promhttp"
-	"k8s.io/klog/v2"
 	"sigs.k8s.io/node-feature-discovery/pkg/version"
 )
 
@@ -33,8 +28,6 @@ const (
 )
 
 var (
-	srv *http.Server
-
 	buildInfo = prometheus.NewGauge(prometheus.GaugeOpts{
 		Name: buildInfoQuery,
 		Help: "Version from which Node Feature Discovery was built.",
@@ -52,24 +45,3 @@ var (
 func registerVersion(version string) {
 	buildInfo.SetToCurrentTime()
 }
-
-// runMetricsServer starts a http server to expose metrics
-func runMetricsServer(port int) {
-	r := prometheus.NewRegistry()
-	r.MustRegister(buildInfo,
-		scanErrors)
-	mux := http.NewServeMux()
-	mux.Handle("/metrics", promhttp.HandlerFor(r, promhttp.HandlerOpts{}))
-
-	klog.InfoS("metrics server starting", "port", port)
-	srv = &http.Server{Addr: fmt.Sprintf(":%d", port), Handler: mux}
-	klog.InfoS("metrics server stopped", "exitCode", srv.ListenAndServe())
-}
-
-// stopMetricsServer stops the metrics server
-func stopMetricsServer() {
-	if srv != nil {
-		klog.InfoS("stopping metrics server", "port", srv.Addr)
-		srv.Close()
-	}
-}

pkg/nfd-topology-updater/nfd-topology-updater.go

@@ -144,9 +144,12 @@ func (w *nfdTopologyUpdater) Run() error {
 
 	// Register to metrics server
 	if w.args.MetricsPort > 0 {
-		go runMetricsServer(w.args.MetricsPort)
+		m := utils.CreateMetricsServer(w.args.MetricsPort,
+			buildInfo,
+			scanErrors)
+		go m.Run()
 		registerVersion(version.Get())
-		defer stopMetricsServer()
+		defer m.Stop()
 	}
 
 	var resScan resourcemonitor.ResourcesScanner

pkg/nfd-worker/metrics.go

@@ -17,16 +17,10 @@ limitations under the License.
 package nfdworker
 
 import (
-	"fmt"
-	"net/http"
-
 	"github.com/prometheus/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/promhttp"
-	"k8s.io/klog/v2"
 	"sigs.k8s.io/node-feature-discovery/pkg/version"
 )
 
-// When adding metric names, see https://prometheus.io/docs/practices/naming/#metric-names
 // When adding metric names, see https://prometheus.io/docs/practices/naming/#metric-names
 const (
 	buildInfoQuery                = "nfd_worker_build_info"
@@ -34,8 +28,6 @@ const (
 )
 
 var (
-	srv *http.Server
-
 	featureDiscoveryDuration = prometheus.NewHistogramVec(
 		prometheus.HistogramOpts{
 			Name:    featureDiscoveryDurationQuery,
@@ -57,25 +49,3 @@ var (
 func registerVersion(version string) {
 	buildInfo.SetToCurrentTime()
 }
-
-// runMetricsServer starts a http server to expose metrics
-func runMetricsServer(port int) {
-	r := prometheus.NewRegistry()
-	r.MustRegister(featureDiscoveryDuration)
-	r.MustRegister(buildInfo)
-
-	mux := http.NewServeMux()
-	mux.Handle("/metrics", promhttp.HandlerFor(r, promhttp.HandlerOpts{}))
-
-	klog.InfoS("metrics server starting", "port", port)
-	srv = &http.Server{Addr: fmt.Sprintf(":%d", port), Handler: mux}
-	klog.InfoS("metrics server stopped", "exit code", srv.ListenAndServe())
-}
-
-// stopMetricsServer stops the metrics server
-func stopMetricsServer() {
-	if srv != nil {
-		klog.InfoS("stopping metrics server", "port", srv.Addr)
-		srv.Close()
-	}
-}

pkg/nfd-worker/nfd-worker.go

@@ -243,9 +243,12 @@ func (w *nfdWorker) Run() error {
 
 	// Register to metrics server
 	if w.args.MetricsPort > 0 {
-		go runMetricsServer(w.args.MetricsPort)
+		m := utils.CreateMetricsServer(w.args.MetricsPort,
+			buildInfo,
+			featureDiscoveryDuration)
+		go m.Run()
 		registerVersion(version.Get())
-		defer stopMetricsServer()
+		defer m.Stop()
 	}
 
 	err = w.runFeatureDiscovery()

pkg/utils/metrics.go

@@ -0,0 +1,54 @@
+/*
+Copyright 2023 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 utils
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"k8s.io/klog/v2"
+)
+
+type MetricsServer struct {
+	srv *http.Server
+}
+
+// RunMetricsServer starts a new http server to expose metrics.
+func CreateMetricsServer(port int, cs ...prometheus.Collector) *MetricsServer {
+	r := prometheus.NewRegistry()
+	r.MustRegister(cs...)
+	mux := http.NewServeMux()
+	mux.Handle("/metrics", promhttp.HandlerFor(r, promhttp.HandlerOpts{}))
+
+	return &MetricsServer{srv: &http.Server{Addr: fmt.Sprintf(":%d", port), Handler: mux}}
+}
+
+// Run runs the metrics server.
+func (s *MetricsServer) Run() {
+	klog.InfoS("metrics server starting", "port", s.srv.Addr)
+	klog.InfoS("metrics server stopped", "exitCode", s.srv.ListenAndServe())
+}
+
+// Stop stops the metrics server.
+func (s *MetricsServer) Stop() {
+	if s.srv != nil {
+		klog.InfoS("stopping metrics server", "port", s.srv.Addr)
+		s.srv.Close()
+	}
+}