General: use client-side round-robin load balancing for grpc (kedacor…

…e#5225) Signed-off-by: Bojan Zelic <bnzelic@gmail.com>
rickbrouwer · Dec 8, 2023 · 19f14a8 · 19f14a8
1 parent 3a7d496
commit 19f14a8
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Showing 5 changed files with 20 additions and 7 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -63,6 +63,7 @@ Here is an overview of all new **experimental** features:
 
 - **General**: Add parameter queryParameters to prometheus-scaler ([#4962](https://github.com/kedacore/keda/issues/4962))
 - **General**: Support TriggerAuthentication properties from ConfigMap ([#4830](https://github.com/kedacore/keda/issues/4830))
+- **General**: Use client-side round-robin load balancing for grpc calls ([#5224](https://github.com/kedacore/keda/issues/5224))
 - **GCP pubsub scaler**: Support distribution-valued metrics and metrics from topics ([#5070](https://github.com/kedacore/keda/issues/5070))
 - **Hashicorp Vault**: Add support to get secret that needs write operation (e.g. pki) ([#5067](https://github.com/kedacore/keda/issues/5067))
 - **Hashicorp Vault**: Fix operator panic when spec.hashiCorpVault.credential.serviceAccount is not set ([#4964](https://github.com/kedacore/keda/issues/4964))

diff --git a/pkg/metricsservice/client.go b/pkg/metricsservice/client.go
@@ -37,7 +37,7 @@ type GrpcClient struct {
 }
 
 func NewGrpcClient(url, certDir string) (*GrpcClient, error) {
-	retryPolicy := `{
+	defaultConfig := `{
 		"methodConfig": [{
 		  "timeout": "3s",
 		  "waitForReady": true,
@@ -55,7 +55,7 @@ func NewGrpcClient(url, certDir string) (*GrpcClient, error) {
 	}
 	opts := []grpc.DialOption{
 		grpc.WithTransportCredentials(creds),
-		grpc.WithDefaultServiceConfig(retryPolicy),
+		grpc.WithDefaultServiceConfig(defaultConfig),
 	}
 	conn, err := grpc.Dial(url, opts...)
 	if err != nil {

diff --git a/pkg/scalers/external_scaler.go b/pkg/scalers/external_scaler.go
@@ -50,6 +50,8 @@ type connectionGroup struct {
 // a pool of connectionGroup per metadata hash
 var connectionPool sync.Map
 
+const grpcConfig = `{"loadBalancingConfig": [{"round_robin":{}}]}`
+
 // NewExternalScaler creates a new external scaler - calls the GRPC interface
 // to create a new scaler
 func NewExternalScaler(config *ScalerConfig) (Scaler, error) {
@@ -311,7 +313,9 @@ func getClientForConnectionPool(metadata externalScalerMetadata, logger logr.Log
 			if err != nil {
 				return nil, err
 			}
-			return grpc.Dial(metadata.scalerAddress, grpc.WithTransportCredentials(creds))
+			return grpc.Dial(metadata.scalerAddress,
+				grpc.WithDefaultServiceConfig(grpcConfig),
+				grpc.WithTransportCredentials(creds))
 		}
 
 		tlsConfig, err := util.NewTLSConfig(metadata.tlsClientCert, metadata.tlsClientKey, metadata.caCert, metadata.unsafeSsl)
@@ -321,10 +325,14 @@ func getClientForConnectionPool(metadata externalScalerMetadata, logger logr.Log
 
 		if len(tlsConfig.Certificates) > 0 || metadata.caCert != "" {
 			// nosemgrep: go.grpc.ssrf.grpc-tainted-url-host.grpc-tainted-url-host
-			return grpc.Dial(metadata.scalerAddress, grpc.WithTransportCredentials(credentials.NewTLS(tlsConfig)))
+			return grpc.Dial(metadata.scalerAddress,
+				grpc.WithDefaultServiceConfig(grpcConfig),
+				grpc.WithTransportCredentials(credentials.NewTLS(tlsConfig)))
 		}
 
-		return grpc.Dial(metadata.scalerAddress, grpc.WithTransportCredentials(insecure.NewCredentials()))
+		return grpc.Dial(metadata.scalerAddress,
+			grpc.WithDefaultServiceConfig(grpcConfig),
+			grpc.WithTransportCredentials(insecure.NewCredentials()))
 	}
 
 	// create a unique key per-metadata. If scaledObjects share the same connection properties

diff --git a/pkg/scalers/external_scaler_test.go b/pkg/scalers/external_scaler_test.go
@@ -246,7 +246,9 @@ func TestWaitForState(t *testing.T) {
 	}()
 
 	// build client connect to server
-	grpcClient, err := grpc.Dial(address, grpc.WithTransportCredentials(insecure.NewCredentials()))
+	grpcClient, err := grpc.Dial(address,
+		grpc.WithDefaultServiceConfig(grpcConfig),
+		grpc.WithTransportCredentials(insecure.NewCredentials()))
 	if err != nil {
 		t.Errorf("connect grpc server %s failed:%s", address, err)
 		return

diff --git a/pkg/scalers/liiklus_scaler.go b/pkg/scalers/liiklus_scaler.go
@@ -69,7 +69,9 @@ func NewLiiklusScaler(config *ScalerConfig) (Scaler, error) {
 		return nil, err
 	}
 
-	conn, err := grpc.Dial(lm.address, grpc.WithTransportCredentials(insecure.NewCredentials()))
+	conn, err := grpc.Dial(lm.address,
+		grpc.WithDefaultServiceConfig(grpcConfig),
+		grpc.WithTransportCredentials(insecure.NewCredentials()))
 	if err != nil {
 		return nil, err
 	}