diff --git a/client/pd_service_discovery.go b/client/pd_service_discovery.go
index e96093f598d..98ddd611326 100644
--- a/client/pd_service_discovery.go
+++ b/client/pd_service_discovery.go
@@ -63,8 +63,6 @@ type ServiceDiscovery interface {
 	GetKeyspaceID() uint32
 	// GetKeyspaceGroupID returns the ID of the keyspace group
 	GetKeyspaceGroupID() uint32
-	// DiscoverServiceURLs discovers the microservice with the specified type and returns the server urls.
-	DiscoverMicroservice(svcType serviceType) ([]string, error)
 	// GetServiceURLs returns the URLs of the servers providing the service
 	GetServiceURLs() []string
 	// GetServingEndpointClientConn returns the grpc client connection of the serving endpoint
@@ -324,7 +322,7 @@ func (c *pdServiceDiscovery) GetKeyspaceGroupID() uint32 {
 }
 
 // DiscoverMicroservice discovers the microservice with the specified type and returns the server urls.
-func (c *pdServiceDiscovery) DiscoverMicroservice(svcType serviceType) (urls []string, err error) {
+func (c *pdServiceDiscovery) discoverMicroservice(svcType serviceType) (urls []string, err error) {
 	switch svcType {
 	case apiService:
 		urls = c.GetServiceURLs()
diff --git a/client/tso_service_discovery.go b/client/tso_service_discovery.go
index 92f95129951..5f14c406797 100644
--- a/client/tso_service_discovery.go
+++ b/client/tso_service_discovery.go
@@ -288,21 +288,6 @@ func (c *tsoServiceDiscovery) GetKeyspaceGroupID() uint32 {
 	return c.keyspaceGroupSD.group.Id
 }
 
-// DiscoverServiceURLs discovers the microservice with the specified type and returns the server urls.
-func (c *tsoServiceDiscovery) DiscoverMicroservice(svcType serviceType) ([]string, error) {
-	var urls []string
-
-	switch svcType {
-	case apiService:
-	case tsoService:
-		return c.apiSvcDiscovery.DiscoverMicroservice(tsoService)
-	default:
-		panic("invalid service type")
-	}
-
-	return urls, nil
-}
-
 // GetServiceURLs returns the URLs of the tso primary/secondary addresses of this keyspace group.
 // For testing use. It should only be called when the client is closed.
 func (c *tsoServiceDiscovery) GetServiceURLs() []string {
@@ -582,7 +567,7 @@ func (c *tsoServiceDiscovery) getTSOServer(sd ServiceDiscovery) (string, error)
 	)
 	t := c.tsoServerDiscovery
 	if len(t.addrs) == 0 || t.failureCount == len(t.addrs) {
-		addrs, err = sd.DiscoverMicroservice(tsoService)
+		addrs, err = sd.(*pdServiceDiscovery).discoverMicroservice(tsoService)
 		if err != nil {
 			return "", err
 		}
diff --git a/pkg/utils/grpcutil/grpcutil.go b/pkg/utils/grpcutil/grpcutil.go
index 44d45ff4c70..a001ec4bd03 100644
--- a/pkg/utils/grpcutil/grpcutil.go
+++ b/pkg/utils/grpcutil/grpcutil.go
@@ -163,6 +163,7 @@ func GetForwardedHost(ctx context.Context) string {
 	md, ok := metadata.FromIncomingContext(ctx)
 	if !ok {
 		log.Debug("failed to get forwarding metadata")
+		return ""
 	}
 	if t, ok := md[ForwardMetadataKey]; ok {
 		return t[0]
diff --git a/server/config/persist_options.go b/server/config/persist_options.go
index 42ab91fce17..ae9047c626b 100644
--- a/server/config/persist_options.go
+++ b/server/config/persist_options.go
@@ -1024,6 +1024,7 @@ func (o *PersistOptions) IsRaftKV2() bool {
 }
 
 // SetRegionBucketEnabled sets if the region bucket is enabled.
+// only used for test.
 func (o *PersistOptions) SetRegionBucketEnabled(enabled bool) {
 	cfg := o.GetStoreConfig().Clone()
 	cfg.SetRegionBucketEnabled(enabled)