CD health check: adjust naming and log messages for clarity

Signed-off-by: Dr. Jan-Philip Gehrcke <[email protected]>

Author: jgehrcke

cmd/compute-domain-kubelet-plugin/driver.go

@@ -122,9 +122,9 @@ func NewDriver(ctx context.Context, config *Config) (*driver, error) {
 		return nil, err
 	}
 
-	healthcheck, err := startHealthcheck(ctx, config)
+	healthcheck, err := setupHealthcheckPrimitives(ctx, config)
 	if err != nil {
-		return nil, fmt.Errorf("start healthcheck: %w", err)
+		return nil, fmt.Errorf("error setting up healtcheck primitives: %w", err)
 	}
 	driver.healthcheck = healthcheck
 

cmd/compute-domain-kubelet-plugin/health.go

@@ -46,16 +46,17 @@ type healthcheck struct {
 	draClient drapb.DRAPluginClient
 }
 
-func startHealthcheck(ctx context.Context, config *Config) (*healthcheck, error) {
+func setupHealthcheckPrimitives(ctx context.Context, config *Config) (*healthcheck, error) {
 	port := config.flags.healthcheckPort
 	if port < 0 {
 		return nil, nil
 	}
 
+	// Bind on all available interfaces.
 	addr := net.JoinHostPort("", strconv.Itoa(port))
 	lis, err := net.Listen("tcp", addr)
 	if err != nil {
-		return nil, fmt.Errorf("failed to listen for healthcheck service at %s: %w", addr, err)
+		return nil, fmt.Errorf("failed to listen on %s: %w", addr, err)
 	}
 
 	regSockPath := (&url.URL{
@@ -64,26 +65,28 @@ func startHealthcheck(ctx context.Context, config *Config) (*healthcheck, error)
 		// are enabled and the filename includes a uid.
 		Path: path.Join(config.flags.kubeletRegistrarDirectoryPath, DriverName+"-reg.sock"),
 	}).String()
-	klog.V(6).Infof("connecting to registration socket path=%s", regSockPath)
+
+	klog.V(6).Infof("Connect to registration socket at %s", regSockPath)
 	regConn, err := grpc.NewClient(
 		regSockPath,
 		grpc.WithTransportCredentials(insecure.NewCredentials()),
 	)
 	if err != nil {
-		return nil, fmt.Errorf("connect to registration socket: %w", err)
+		return nil, fmt.Errorf("error connecting to registration socket: %w", err)
 	}
 
 	draSockPath := (&url.URL{
 		Scheme: "unix",
 		Path:   path.Join(config.DriverPluginPath(), "dra.sock"),
 	}).String()
-	klog.V(6).Infof("connecting to DRA socket path=%s", draSockPath)
+
+	klog.V(6).Infof("Connect to plugin socket at %s", draSockPath)
 	draConn, err := grpc.NewClient(
 		draSockPath,
 		grpc.WithTransportCredentials(insecure.NewCredentials()),
 	)
 	if err != nil {
-		return nil, fmt.Errorf("connect to DRA socket: %w", err)
+		return nil, fmt.Errorf("error connecting to plugin socket: %w", err)
 	}
 
 	server := grpc.NewServer()
@@ -97,9 +100,10 @@ func startHealthcheck(ctx context.Context, config *Config) (*healthcheck, error)
 	healthcheck.wg.Add(1)
 	go func() {
 		defer healthcheck.wg.Done()
-		klog.Infof("starting healthcheck service at %s", lis.Addr().String())
+		klog.Infof("Starting healthcheck server on %s", lis.Addr().String())
 		if err := server.Serve(lis); err != nil {
-			klog.Errorf("failed to serve healthcheck service on %s: %v", addr, err)
+			// Note(JP): let's review if this should be fatal
+			klog.Errorf("failed to start healthcheck server: %v", err)
 		}
 	}()
 
@@ -108,13 +112,13 @@ func startHealthcheck(ctx context.Context, config *Config) (*healthcheck, error)
 
 func (h *healthcheck) Stop() {
 	if h.server != nil {
-		klog.Info("Stopping healthcheck service")
+		klog.Info("Stopping healthcheck server")
 		h.server.GracefulStop()
 	}
 	h.wg.Wait()
 }
 
-// Check implements [grpc_health_v1.HealthServer].
+// Check implements [grpc_health_v1.HealthServer.Check].
 func (h *healthcheck) Check(ctx context.Context, req *grpc_health_v1.HealthCheckRequest) (*grpc_health_v1.HealthCheckResponse, error) {
 	knownServices := map[string]struct{}{"": {}, "liveness": {}}
 	if _, known := knownServices[req.GetService()]; !known {
@@ -125,16 +129,19 @@ func (h *healthcheck) Check(ctx context.Context, req *grpc_health_v1.HealthCheck
 		Status: grpc_health_v1.HealthCheckResponse_NOT_SERVING,
 	}
 
+	// This simulates the kubelet reaching out to the plugin for discovery
+	// (towards registering it).
 	info, err := h.regClient.GetInfo(ctx, &registerapi.InfoRequest{})
 	if err != nil {
-		klog.ErrorS(err, "failed to call GetInfo")
+		klog.ErrorS(err, "failed to call GetInfo on registration socket")
 		return status, nil
 	}
 	klog.V(6).Infof("Successfully invoked GetInfo: %v", info)
 
+	// This simulates the kubelet reaching out to the plugin
 	_, err = h.draClient.NodePrepareResources(ctx, &drapb.NodePrepareResourcesRequest{})
 	if err != nil {
-		klog.ErrorS(err, "failed to call NodePrepareResources")
+		klog.ErrorS(err, "failed to call NodePrepareResources on plugin socket")
 		return status, nil
 	}
 	klog.V(6).Info("Successfully invoked NodePrepareResources")