Update GetAzureQueueLength in azure storage queue scaler to consider queueLengthStrategy (#5875)

Signed-off-by: Leonardo D'Ippolito <[email protected]>

Author: leodip

CHANGELOG.md

@@ -75,6 +75,7 @@ Here is an overview of all new **experimental** features:
 
 ### Improvements
 
+- **Azure queue scaler**: Added new configuration option 'queueLengthStrategy' ([#4478](https://github.com/kedacore/keda/issues/4478))
 - **Cassandra Scaler**: Add TLS support for cassandra scaler ([#5802](https://github.com/kedacore/keda/issues/5802))
 - **GCP Pub/Sub**: Add optional valueIfNull to allow a default scaling value and prevent errors when GCP metric returns no value. ([#5896](https://github.com/kedacore/keda/issues/5896))
 - **GCP Scalers**: Added custom time horizon in GCP scalers ([#5778](https://github.com/kedacore/keda/issues/5778))

pkg/scalers/azure_queue_scaler.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"fmt"
 	"strconv"
+	"strings"
 
 	"github.com/Azure/azure-sdk-for-go/sdk/storage/azqueue"
 	"github.com/go-logr/logr"
@@ -33,10 +34,16 @@ import (
 )
 
 const (
-	queueLengthMetricName           = "queueLength"
-	activationQueueLengthMetricName = "activationQueueLength"
-	defaultTargetQueueLength        = 5
-	externalMetricType              = "External"
+	queueLengthMetricName                  = "queueLength"
+	activationQueueLengthMetricName        = "activationQueueLength"
+	defaultTargetQueueLength               = 5
+	externalMetricType                     = "External"
+	QueueLengthStrategyAll          string = "all"
+	QueueLengthStrategyVisibleOnly  string = "visibleonly"
+)
+
+var (
+	maxPeekMessages int32 = 32
 )
 
 type azureQueueScaler struct {
@@ -53,6 +60,7 @@ type azureQueueMetadata struct {
 	connection                  string
 	accountName                 string
 	endpointSuffix              string
+	queueLengthStrategy         string
 	triggerIndex                int
 }
 
@@ -123,6 +131,17 @@ func parseAzureQueueMetadata(config *scalersconfig.ScalerConfig, logger logr.Log
 		return nil, kedav1alpha1.AuthPodIdentity{}, fmt.Errorf("no queueName given")
 	}
 
+	if val, ok := config.TriggerMetadata["queueLengthStrategy"]; ok && val != "" {
+		strategy := strings.ToLower(val)
+		if strategy == QueueLengthStrategyAll || strategy == QueueLengthStrategyVisibleOnly {
+			meta.queueLengthStrategy = strategy
+		} else {
+			return nil, kedav1alpha1.AuthPodIdentity{}, fmt.Errorf("invalid queueLengthStrategy %s given", val)
+		}
+	} else {
+		meta.queueLengthStrategy = QueueLengthStrategyAll
+	}
+
 	// If the Use AAD Pod Identity is not present, or set to "none"
 	// then check for connection string
 	switch config.PodIdentity.Provider {
@@ -172,12 +191,35 @@ func (s *azureQueueScaler) GetMetricSpecForScaling(context.Context) []v2.MetricS
 
 // GetMetricsAndActivity returns value for a supported metric and an error if there is a problem getting the metric
 func (s *azureQueueScaler) GetMetricsAndActivity(ctx context.Context, metricName string) ([]external_metrics.ExternalMetricValue, bool, error) {
-	props, err := s.queueClient.GetProperties(ctx, nil)
+	queuelen, err := s.getMessageCount(ctx)
 	if err != nil {
 		s.logger.Error(err, "error getting queue length")
 		return []external_metrics.ExternalMetricValue{}, false, err
 	}
-	queuelen := int64(*props.ApproximateMessagesCount)
+
 	metric := GenerateMetricInMili(metricName, float64(queuelen))
 	return []external_metrics.ExternalMetricValue{metric}, queuelen > s.metadata.activationTargetQueueLength, nil
 }
+
+func (s *azureQueueScaler) getMessageCount(ctx context.Context) (int64, error) {
+	strategy := strings.ToLower(s.metadata.queueLengthStrategy)
+	if strategy == QueueLengthStrategyVisibleOnly {
+		queue, err := s.queueClient.PeekMessages(ctx, &azqueue.PeekMessagesOptions{NumberOfMessages: &maxPeekMessages})
+		if err != nil {
+			return 0, err
+		}
+		visibleMessageCount := len(queue.Messages)
+
+		// Queue has less messages than we allowed to peek for,
+		// so no need to fall back to the 'all' strategy
+		if visibleMessageCount < int(maxPeekMessages) {
+			return int64(visibleMessageCount), nil
+		}
+	}
+
+	props, err := s.queueClient.GetProperties(ctx, nil)
+	if err != nil {
+		return 0, err
+	}
+	return int64(*props.ApproximateMessagesCount), nil
+}