Add optional pprof endpoint support to multus-daemon

Add pprof profiling endpoints to the metrics server, gated behind
a new EnablePprof config field. When enabled, standard Go pprof
handlers are registered on the metrics port under /debug/pprof/.

This also improves the metrics server setup:
- Use dedicated http.ServeMux instead of DefaultServeMux
- Move mux/handler setup outside the retry loop
- Use http.Server with ReadHeaderTimeout for resource safety
- Add graceful shutdown on context cancellation

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Benjamin Pickard <bpickard@redhat.com>

cmd/multus-daemon/main.go

@@ -22,12 +22,14 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"net/http/pprof"
 	"os"
 	"os/signal"
 	"os/user"
 	"path/filepath"
 	"sync"
 	"syscall"
+	"time"
 
 	utilwait "k8s.io/apimachinery/pkg/util/wait"
 
@@ -155,11 +157,31 @@ func startMultusDaemon(ctx context.Context, daemonConfig *srv.ControllerNetConf,
 	}
 
 	if daemonConfig.MetricsPort != nil {
+		mux := http.NewServeMux()
+		mux.Handle("/metrics", promhttp.Handler())
+		if daemonConfig.EnablePprof != nil && *daemonConfig.EnablePprof {
+			mux.HandleFunc("/debug/pprof/", 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)
+			logging.Verbosef("pprof endpoints enabled on metrics port %d", *daemonConfig.MetricsPort)
+		}
+		metricsSrv := &http.Server{
+			Addr:              fmt.Sprintf(":%d", *daemonConfig.MetricsPort),
+			Handler:           mux,
+			ReadHeaderTimeout: 10 * time.Second,
+		}
+		logging.Debugf("metrics port: %d", *daemonConfig.MetricsPort)
 		go utilwait.UntilWithContext(ctx, func(_ context.Context) {
-			http.Handle("/metrics", promhttp.Handler())
-			logging.Debugf("metrics port: %d", *daemonConfig.MetricsPort)
-			logging.Debugf("metrics: %s", http.ListenAndServe(fmt.Sprintf(":%d", *daemonConfig.MetricsPort), nil))
+			if err := metricsSrv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+				logging.Debugf("metrics server error: %v", err)
+			}
 		}, 0)
+		go func() {
+			<-ctx.Done()
+			metricsSrv.Shutdown(context.Background())
+		}()
 	}
 
 	l, err := srv.GetListener(api.SocketPath(daemonConfig.SocketDir))

pkg/server/types.go

@@ -78,7 +78,8 @@ type ControllerNetConf struct {
 	LogToStderr        bool                `json:"logToStderr,omitempty"`
 	PerNodeCertificate *PerNodeCertificate `json:"perNodeCertificate,omitempty"`
 
-	MetricsPort *int `json:"metricsPort,omitempty"`
+	MetricsPort *int  `json:"metricsPort,omitempty"`
+	EnablePprof *bool `json:"enablePprof,omitempty"`
 
 	// Option to point to the path of the unix domain socket through which the
 	// multus client / server communicate.