grpc client: wait properly for establishing a connection (#3938)

Signed-off-by: Zbynek Roubalik <zroubalik@gmail.com> Signed-off-by: Zbynek Roubalik <zroubalik@gmail.com>
kedacore · Nov 30, 2022 · 0f21eac · 0f21eac
1 parent e78e112
commit 0f21eac
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Showing 3 changed files with 49 additions and 15 deletions.
diff --git a/apis/keda/v1alpha1/indentifier.go → apis/keda/v1alpha1/identifier.go b/apis/keda/v1alpha1/indentifier.go → apis/keda/v1alpha1/identifier.go
diff --git a/pkg/metricsservice/client.go b/pkg/metricsservice/client.go
@@ -19,8 +19,11 @@ package metricsservice
 import (
 	"context"
 	"fmt"
+	"time"
 
+	"github.com/go-logr/logr"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/connectivity"
 	"google.golang.org/grpc/credentials/insecure"
 	"k8s.io/metrics/pkg/apis/external_metrics"
 	"k8s.io/metrics/pkg/apis/external_metrics/v1beta1"
@@ -29,7 +32,8 @@ import (
 )
 
 type GrpcClient struct {
-	client api.MetricsServiceClient
+	client     api.MetricsServiceClient
+	connection *grpc.ClientConn
 }
 
 func NewGrpcClient(url string) (*GrpcClient, error) {
@@ -51,7 +55,7 @@ func NewGrpcClient(url string) (*GrpcClient, error) {
 		return nil, err
 	}
 
-	return &GrpcClient{client: api.NewMetricsServiceClient(conn)}, nil
+	return &GrpcClient{client: api.NewMetricsServiceClient(conn), connection: conn}, nil
 }
 
 func (c *GrpcClient) GetMetrics(ctx context.Context, scaledObjectName, scaledObjectNamespace, metricName string) (*external_metrics.ExternalMetricValueList, *api.PromMetricsMsg, error) {
@@ -68,3 +72,26 @@ func (c *GrpcClient) GetMetrics(ctx context.Context, scaledObjectName, scaledObj
 
 	return extMetrics, response.GetPromMetrics(), nil
 }
+
+// WaitForConnectionReady waits for gRPC connection to be ready
+// returns true if the connection was successful, false if we hit a timeut from context
+func (c *GrpcClient) WaitForConnectionReady(ctx context.Context, logger logr.Logger) bool {
+	currentState := c.connection.GetState()
+	if currentState != connectivity.Ready {
+		logger.Info("Waiting for establishing a gRPC connection to KEDA Metrics Server")
+		for {
+			select {
+			case <-ctx.Done():
+				return false
+			default:
+				c.connection.Connect()
+				time.Sleep(500 * time.Millisecond)
+				currentState := c.connection.GetState()
+				if currentState == connectivity.Ready {
+					return true
+				}
+			}
+		}
+	}
+	return true
+}
diff --git a/pkg/provider/provider.go b/pkg/provider/provider.go
@@ -92,27 +92,34 @@ func (p *KedaProvider) GetExternalMetric(ctx context.Context, namespace string,
 
 	// Get Metrics from Metrics Service gRPC Server
 	if p.useMetricsServiceGrpc {
+		if !p.grpcClient.WaitForConnectionReady(ctx, logger) {
+			logger.Error(fmt.Errorf("timeout while waiting to establish gRPC connection to KEDA Metrics Server"), "timeout")
+			return nil, err
+		}
+
 		// selector is in form: `scaledobject.keda.sh/name: scaledobject-name`
 		scaledObjectName := selector.Get("scaledobject.keda.sh/name")
 
 		metrics, promMetrics, err := p.grpcClient.GetMetrics(ctx, scaledObjectName, namespace, info.Metric)
 		logger.V(1).WithValues("scaledObjectName", scaledObjectName, "scaledObjectNamespace", namespace, "metrics", metrics).Info("Receiving metrics")
 
 		// [DEPRECATED] handle exporting Prometheus metrics from Operator to Metrics Server
-		var scaledObjectErr error
-		if promMetrics.ScaledObjectErr {
-			scaledObjectErr = fmt.Errorf("scaledObject error")
-		}
-		promMetricsServer.RecordScaledObjectError(namespace, scaledObjectName, scaledObjectErr)
-		for _, scalerMetric := range promMetrics.ScalerMetric {
-			promMetricsServer.RecordHPAScalerMetric(namespace, scaledObjectName, scalerMetric.ScalerName, int(scalerMetric.ScalerIndex), scalerMetric.MetricName, float64(scalerMetric.MetricValue))
-		}
-		for _, scalerError := range promMetrics.ScalerError {
-			var scalerErr error
-			if scalerError.Error {
-				scalerErr = fmt.Errorf("scaler error")
+		if promMetrics != nil {
+			var scaledObjectErr error
+			if promMetrics.ScaledObjectErr {
+				scaledObjectErr = fmt.Errorf("scaledObject error")
+			}
+			promMetricsServer.RecordScaledObjectError(namespace, scaledObjectName, scaledObjectErr)
+			for _, scalerMetric := range promMetrics.ScalerMetric {
+				promMetricsServer.RecordHPAScalerMetric(namespace, scaledObjectName, scalerMetric.ScalerName, int(scalerMetric.ScalerIndex), scalerMetric.MetricName, float64(scalerMetric.MetricValue))
+			}
+			for _, scalerError := range promMetrics.ScalerError {
+				var scalerErr error
+				if scalerError.Error {
+					scalerErr = fmt.Errorf("scaler error")
+				}
+				promMetricsServer.RecordHPAScalerError(namespace, scaledObjectName, scalerError.ScalerName, int(scalerError.ScalerIndex), scalerError.MetricName, scalerErr)
 			}
-			promMetricsServer.RecordHPAScalerError(namespace, scaledObjectName, scalerError.ScalerName, int(scalerError.ScalerIndex), scalerError.MetricName, scalerErr)
 		}
 
 		return metrics, err