Filter returned metrics from api server based on queried name (#732)

Signed-off-by: ycabrer <43866176+ycabrer@users.noreply.github.com>

pkg/provider/provider.go

@@ -3,6 +3,7 @@ package provider
 import (
 	"context"
 	"fmt"
+	"strings"
 
 	kedav1alpha1 "github.com/kedacore/keda/pkg/apis/keda/v1alpha1"
 	"github.com/kedacore/keda/pkg/handler"
@@ -83,16 +84,27 @@ func (p *KedaProvider) GetExternalMetric(namespace string, metricSelector labels
 	}
 
 	for _, scaler := range scalers {
-		metrics, err := scaler.GetMetrics(context.TODO(), info.Metric, metricSelector)
-		if err != nil {
-			logger.Error(err, "error getting metric for scaler", "ScaledObject.Namespace", scaledObject.Namespace, "ScaledObject.Name", scaledObject.Name, "Scaler", scaler)
-		} else {
-			matchingMetrics = append(matchingMetrics, metrics...)
+		metricSpecs := scaler.GetMetricSpecForScaling()
+
+		for _, metricSpec := range metricSpecs {
+			// Filter only the desired metric
+			if strings.EqualFold(metricSpec.External.MetricName, info.Metric) {
+				metrics, err := scaler.GetMetrics(context.TODO(), info.Metric, metricSelector)
+				if err != nil {
+					logger.Error(err, "error getting metric for scaler", "ScaledObject.Namespace", scaledObject.Namespace, "ScaledObject.Name", scaledObject.Name, "Scaler", scaler)
+				} else {
+					matchingMetrics = append(matchingMetrics, metrics...)
+				}
+			}
 		}
 
 		scaler.Close()
 	}
 
+	if len(matchingMetrics) <= 0 {
+		return nil, fmt.Errorf("No matching metrics found for " + info.Metric)
+	}
+
 	return &external_metrics.ExternalMetricValueList{
 		Items: matchingMetrics,
 	}, nil