nfd-worker: Add liveness probe

Signed-off-by: Oleg Zhurakivskyy <[email protected]>

cmd/nfd-worker/main.go

@@ -31,7 +31,8 @@ import (
 
 const (
 	// ProgramName is the canonical name of this program
-	ProgramName = "nfd-worker"
+	ProgramName    = "nfd-worker"
+	GrpcHealthPort = 8082
 )
 
 func main() {
@@ -73,6 +74,7 @@ func main() {
 	utils.ConfigureGrpcKlog()
 
 	// Get new NfdWorker instance
+	args.GrpcHealthPort = GrpcHealthPort
 	instance, err := worker.NewNfdWorker(args)
 	if err != nil {
 		klog.ErrorS(err, "failed to initialize NfdWorker instance")

deployment/base/worker-daemonset/worker-daemonset.yaml

@@ -19,6 +19,17 @@ spec:
         - name: nfd-worker
           image: gcr.io/k8s-staging-nfd/node-feature-discovery:master
           imagePullPolicy: Always
+          livenessProbe:
+            grpc:
+              port: 8082
+            initialDelaySeconds: 10
+            periodSeconds: 10
+          readinessProbe:
+            grpc:
+              port: 8082
+            initialDelaySeconds: 5
+            periodSeconds: 10
+            failureThreshold: 10
           command:
             - "nfd-worker"
           args:

pkg/nfd-worker/nfd-worker.go

@@ -21,6 +21,7 @@ import (
 	"crypto/x509"
 	"encoding/json"
 	"fmt"
+	"net"
 	"os"
 	"path/filepath"
 	"regexp"
@@ -33,6 +34,8 @@ import (
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/credentials/insecure"
+	"google.golang.org/grpc/health"
+	"google.golang.org/grpc/health/grpc_health_v1"
 	"k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/validation"
@@ -104,6 +107,7 @@ type Args struct {
 	Server               string
 	ServerNameOverride   string
 	MetricsPort          int
+	GrpcHealthPort       int
 
 	Overrides ConfigOverrideArgs
 }
@@ -124,6 +128,7 @@ type nfdWorker struct {
 	config              *NFDConfig
 	kubernetesNamespace string
 	grpcClient          pb.LabelerClient
+	healthServer        *grpc.Server
 	nfdClient           *nfdclient.Clientset
 	stop                chan struct{} // channel for signaling stop
 	featureSources      []source.FeatureSource
@@ -187,6 +192,29 @@ func (i *infiniteTicker) Reset(d time.Duration) {
 	}
 }
 
+func (w *nfdWorker) startGrpcHealthServer(errChan chan<- error) error {
+	lis, err := net.Listen("tcp", fmt.Sprintf(":%d", w.args.GrpcHealthPort))
+	if err != nil {
+		return fmt.Errorf("failed to listen: %w", err)
+	}
+
+	s := grpc.NewServer()
+	grpc_health_v1.RegisterHealthServer(s, health.NewServer())
+	klog.InfoS("gRPC health server serving", "port", w.args.GrpcHealthPort)
+
+	go func() {
+		defer func() {
+			lis.Close()
+		}()
+		if err := s.Serve(lis); err != nil {
+			errChan <- fmt.Errorf("gRPC health server exited with an error: %w", err)
+		}
+		klog.InfoS("gRPC health server stopped")
+	}()
+	w.healthServer = s
+	return nil
+}
+
 // Run feature discovery.
 func (w *nfdWorker) runFeatureDiscovery() error {
 	discoveryStart := time.Now()
@@ -262,8 +290,20 @@ func (w *nfdWorker) Run() error {
 		return nil
 	}
 
+	grpcErr := make(chan error, 1)
+
+	// Start gRPC server for liveness probe (at this point we're "live")
+	if w.args.GrpcHealthPort != 0 {
+		if err := w.startGrpcHealthServer(grpcErr); err != nil {
+			return fmt.Errorf("failed to start gRPC health server: %w", err)
+		}
+	}
+
 	for {
 		select {
+		case err := <-grpcErr:
+			return fmt.Errorf("error in serving gRPC: %w", err)
+
 		case <-labelTrigger.C:
 			err = w.runFeatureDiscovery()
 			if err != nil {
@@ -294,6 +334,9 @@ func (w *nfdWorker) Run() error {
 
 		case <-w.stop:
 			klog.InfoS("shutting down nfd-worker")
+			if w.healthServer != nil {
+				w.healthServer.GracefulStop()
+			}
 			configWatch.Close()
 			w.certWatch.Close()
 			return nil