fix: enhance fallback condition checks for ScalingModifiers with default metricType (#6562)

Signed-off-by: Zbynek Roubalik <[email protected]>

Author: zroubalik

pkg/fallback/fallback.go

@@ -40,13 +40,13 @@ func isFallbackEnabled(scaledObject *kedav1alpha1.ScaledObject, metricSpec v2.Me
 		return false
 	}
 
-	// If we are using ScalingModifiers, we only care whether its metric type is AverageValue.
+	// If we are using ScalingModifiers, we only care whether its metric type is AverageValue (or not not set -> default, which is AverageValue).
 	// If not, test the type of metricSpec passed.
-	if scaledObject.IsUsingModifiers() && scaledObject.Spec.Advanced.ScalingModifiers.MetricType != v2.AverageValueMetricType {
-		log.V(0).Info("Fallback can only be enabled for scalingModifiers with metric of type AverageValue", "scaledObject.Namespace", scaledObject.Namespace, "scaledObject.Name", scaledObject.Name)
+	if scaledObject.IsUsingModifiers() && (scaledObject.Spec.Advanced.ScalingModifiers.MetricType != v2.AverageValueMetricType && scaledObject.Spec.Advanced.ScalingModifiers.MetricType != "") {
+		log.V(0).Info("Fallback can only be enabled for scalingModifiers with metric of type AverageValue", "scaledObject.Namespace", scaledObject.Namespace, "scaledObject.Name", scaledObject.Name, "scalingModifiers.MetricType", scaledObject.Spec.Advanced.ScalingModifiers.MetricType)
 		return false
 	} else if !scaledObject.IsUsingModifiers() && metricSpec.External.Target.Type != v2.AverageValueMetricType {
-		log.V(0).Info("Fallback can only be enabled for triggers with metric of type AverageValue", "scaledObject.Namespace", scaledObject.Namespace, "scaledObject.Name", scaledObject.Name)
+		log.V(0).Info("Fallback can only be enabled for triggers with metric of type AverageValue", "scaledObject.Namespace", scaledObject.Namespace, "scaledObject.Name", scaledObject.Name, "metricSpec.External.Target.Type", metricSpec.External.Target.Type)
 		return false
 	}