✨ pkg/manager,metrics: Expose ServingMetrics func

pkg/manager/internal.go

@@ -20,11 +20,9 @@ import (
 	"context"
 	"fmt"
 	"net"
-	"net/http"
 	"sync"
 	"time"
 
-	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"k8s.io/apimachinery/pkg/api/meta"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/client-go/rest"
@@ -199,28 +197,8 @@ func (cm *controllerManager) GetWebhookServer() *webhook.Server {
 }
 
 func (cm *controllerManager) serveMetrics(stop <-chan struct{}) {
-	handler := promhttp.HandlerFor(metrics.Registry, promhttp.HandlerOpts{
-		ErrorHandling: promhttp.HTTPErrorOnError,
-	})
-	// TODO(JoelSpeed): Use existing Kubernetes machinery for serving metrics
-	mux := http.NewServeMux()
-	mux.Handle("/metrics", handler)
-	server := http.Server{
-		Handler: mux,
-	}
-	// Run the server
-	go func() {
-		if err := server.Serve(cm.metricsListener); err != nil && err != http.ErrServerClosed {
-			cm.errChan <- err
-		}
-	}()
-
-	// Shutdown the server when stop is closed
-	select {
-	case <-stop:
-		if err := server.Shutdown(context.Background()); err != nil {
-			cm.errChan <- err
-		}
+	if err := metrics.ServeMetrics(cm.metricsListener, stop); err != nil {
+		cm.errChan <- err
 	}
 }
 

pkg/metrics/server.go

@@ -0,0 +1,59 @@
+/*
+Copyright 2019 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 (
+	"context"
+	"net"
+	"net/http"
+
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+// ServeMetrics serves the metrics until the stop channel is closed.
+// It serves the metrics on `/metrics` on the port configured through the MetricsBindAddress.
+func ServeMetrics(listener net.Listener, stop <-chan struct{}) error {
+	handler := promhttp.HandlerFor(Registry, promhttp.HandlerOpts{
+		ErrorHandling: promhttp.HTTPErrorOnError,
+	})
+	// TODO(JoelSpeed): Use existing Kubernetes machinery for serving metrics
+	mux := http.NewServeMux()
+	mux.Handle("/metrics", handler)
+	server := http.Server{
+		Handler: mux,
+	}
+
+	errc := make(chan error, 0)
+	// Run the server
+	go func() {
+		if err := server.Serve(listener); err != nil && err != http.ErrServerClosed {
+			errc <- err
+		}
+	}()
+
+	// Shutdown the server when stop is closed and catch any errors.
+	select {
+	case err := <-errc:
+		return err
+	case <-stop:
+		if err := server.Shutdown(context.Background()); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}