optimize metrics registration.

Signed-off-by: morvencao <lcao@redhat.com>

rh-pre-commit.version: 2.3.2
rh-pre-commit.check-secrets: ENABLED

Author: morvencao

pkg/cloudevents/server/grpc/metrics/metrics.go

@@ -3,15 +3,11 @@ package metrics
 import (
 	"context"
 	"fmt"
-	"sync"
 	"time"
 
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/status"
 
-	"k8s.io/component-base/metrics/legacyregistry"
-	"k8s.io/klog/v2"
-
 	"github.com/cloudevents/sdk-go/v2/binding"
 	cetypes "github.com/cloudevents/sdk-go/v2/types"
 	pbv1 "open-cluster-management.io/sdk-go/pkg/cloudevents/generic/options/grpc/protobuf/v1"
@@ -21,9 +17,6 @@ import (
 	k8smetrics "k8s.io/component-base/metrics"
 )
 
-// ensure metrics are registered only once
-var once sync.Once
-
 // subsystem used to define the metrics of grpc server for cloud events
 const grpcCEMetricsSubsystem = "grpc_server_ce"
 
@@ -285,22 +278,12 @@ func SplitMethod(fullMethod string) (service, method string) {
 }
 
 // Register all the grpc server metrics for cloudevents.
-func RegisterCloudEventsGRPCMetrics() {
-	once.Do(func() {
-		metrics := []k8smetrics.Registerable{
-			grpcCECalledCountMetric,
-			grpcCEProcessedCountMetric,
-			grpcCEProcessingDurationMetric,
-			grpcCEMessageReceivedCountMetric,
-			grpcCEMessageSentCountMetric,
-		}
-
-		for _, m := range metrics {
-			if m != nil {
-				legacyregistry.MustRegister(m)
-			} else {
-				klog.Errorf("failed to register nil grpc server metric")
-			}
-		}
-	})
+func CloudEventsGRPCMetrics() []k8smetrics.Registerable {
+	return []k8smetrics.Registerable{
+		grpcCECalledCountMetric,
+		grpcCEProcessedCountMetric,
+		grpcCEProcessingDurationMetric,
+		grpcCEMessageReceivedCountMetric,
+		grpcCEMessageSentCountMetric,
+	}
 }

pkg/server/grpc/metrics/metrics.go

@@ -97,14 +97,16 @@ func NewGRPCMetricsStreamInterceptor(promServerMetrics *prom.ServerMetrics) grpc
 }
 
 // Register all the grpc server metrics.
-func RegisterGRPCMetrics(promServerMetrics *prom.ServerMetrics) {
+func RegisterGRPCMetrics(promServerMetrics *prom.ServerMetrics, extraMetrics ...k8smetrics.Registerable) {
 	once.Do(func() {
 		metrics := []k8smetrics.Registerable{
 			grpcServerConnections,
 			grpcServerMsgRevBytes,
 			grpcServerMsgSentBytes,
 		}
 
+		metrics = append(metrics, extraMetrics...)
+
 		for _, m := range metrics {
 			if m != nil {
 				legacyregistry.MustRegister(m)

pkg/server/grpc/metrics/metrics_test.go

@@ -47,8 +47,7 @@ func startBufServer(t *testing.T) *grpc.Server {
 	grpcBroker.RegisterService(payload.ManifestBundleEventDataType, newMockWorkService())
 	pbv1.RegisterCloudEventServiceServer(server, grpcBroker)
 
-	RegisterGRPCMetrics(promMiddleware)
-	cemetrics.RegisterCloudEventsGRPCMetrics()
+	RegisterGRPCMetrics(promMiddleware, cemetrics.CloudEventsGRPCMetrics()...)
 	promMiddleware.InitializeMetrics(server)
 
 	lis = bufconn.Listen(bufSize)

pkg/server/grpc/server.go

@@ -23,6 +23,7 @@ import (
 
 type GRPCServer struct {
 	options           *GRPCServerOptions
+	extraMetrics      []k8smetrics.Registerable
 	registerFuncs     []func(*grpc.Server)
 	authenticators    []authn.Authenticator
 	unaryAuthorizers  []authz.UnaryAuthorizer
@@ -40,6 +41,11 @@ func (b *GRPCServer) WithRegisterFunc(registerFunc func(*grpc.Server)) *GRPCServ
 	return b
 }
 
+func (b *GRPCServer) WithExtraMetrics(metrics ...k8smetrics.Registerable) *GRPCServer {
+	b.extraMetrics = append(b.extraMetrics, metrics...)
+	return b
+}
+
 func (b *GRPCServer) WithAuthenticator(authenticator authn.Authenticator) *GRPCServer {
 	b.authenticators = append(b.authenticators, authenticator)
 	return b
@@ -124,7 +130,7 @@ func (b *GRPCServer) Run(ctx context.Context) error {
 
 	grpcServer := grpc.NewServer(grpcServerOptions...)
 	// register all the general grpc server metrics
-	metrics.RegisterGRPCMetrics(promMiddleware)
+	metrics.RegisterGRPCMetrics(promMiddleware, b.extraMetrics...)
 	// initialize grpc server metrics with appropriate value.
 	promMiddleware.InitializeMetrics(grpcServer)
 

pkg/server/grpc/server_test.go

@@ -9,6 +9,8 @@ import (
 
 	"google.golang.org/grpc"
 	certutil "k8s.io/client-go/util/cert"
+
+	cemetrics "open-cluster-management.io/sdk-go/pkg/cloudevents/server/grpc/metrics"
 )
 
 // testAuthenticator implements Authenticator for testing
@@ -133,6 +135,18 @@ func TestGRPCServerBuilder_WithRegisterFunc(t *testing.T) {
 	}
 }
 
+func TestGRPCServerBuilder_WithExtraMetrics(t *testing.T) {
+	opt := NewGRPCServerOptions()
+	builder := NewGRPCServer(opt)
+
+	// Test add extra metrics
+	builder.WithExtraMetrics(cemetrics.CloudEventsGRPCMetrics()...)
+
+	if builder.extraMetrics == nil || len(builder.extraMetrics) != len(cemetrics.CloudEventsGRPCMetrics()) {
+		t.Error("Expected extra metrics to be registered")
+	}
+}
+
 func TestGRPCServerBuilder_WithAuthenticator(t *testing.T) {
 	opt := NewGRPCServerOptions()
 	builder := NewGRPCServer(opt)

test/integration/cloudevents/suite_test.go

@@ -25,12 +25,13 @@ import (
 	sdkgrpc "open-cluster-management.io/sdk-go/pkg/server/grpc"
 	grpcauthn "open-cluster-management.io/sdk-go/pkg/server/grpc/authn"
 
-	cemetrics "open-cluster-management.io/sdk-go/pkg/cloudevents/server/grpc/metrics"
 	clienttesting "open-cluster-management.io/sdk-go/pkg/testing"
 	"open-cluster-management.io/sdk-go/test/integration/cloudevents/broker/services"
 	"open-cluster-management.io/sdk-go/test/integration/cloudevents/server"
 	"open-cluster-management.io/sdk-go/test/integration/cloudevents/store"
 	"open-cluster-management.io/sdk-go/test/integration/cloudevents/util"
+
+	cemetrics "open-cluster-management.io/sdk-go/pkg/cloudevents/server/grpc/metrics"
 )
 
 const (
@@ -151,10 +152,7 @@ var _ = ginkgo.BeforeSuite(func(done ginkgo.Done) {
 		WithRegisterFunc(func(s *grpc.Server) {
 			pbv1.RegisterCloudEventServiceServer(s, grpcBroker)
 		}).
-		WithRegisterFunc(func(s *grpc.Server) {
-			// register grpc metrics for cloud events
-			cemetrics.RegisterCloudEventsGRPCMetrics()
-		})
+		WithExtraMetrics(cemetrics.CloudEventsGRPCMetrics()...)
 
 	go func() {
 		err := grpcServer.Run(context.Background())