Update GetAzureQueueLength in azure queue scaler, to support differen…

…t queue length strategies.

Signed-off-by: Leonardo D'Ippolito <leodip@outlook.com>

CHANGELOG.md

@@ -70,6 +70,7 @@ 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))
 - **GCP Scalers**: Added custom time horizon in GCP scalers ([#5778](https://github.com/kedacore/keda/issues/5778))
 - **GitHub Scaler**: Fixed pagination, fetching repository list ([#5738](https://github.com/kedacore/keda/issues/5738))
 - **Kafka**: Fix logic to scale to zero on invalid offset even with earliest offsetResetPolicy ([#5689](https://github.com/kedacore/keda/issues/5689))

pkg/scalers/azure/azure_queue.go

@@ -18,14 +18,19 @@ package azure
 
 import (
 	"context"
+	"strings"
 
 	"github.com/Azure/azure-storage-queue-go/azqueue"
 
 	kedav1alpha1 "github.com/kedacore/keda/v2/apis/keda/v1alpha1"
 )
 
+const (
+	maxPeekMessages int32 = 32
+)
+
 // GetAzureQueueLength returns the length of a queue in int, see https://learn.microsoft.com/en-us/azure/storage/queues/storage-dotnet-how-to-use-queues?tabs=dotnet#get-the-queue-length
-func GetAzureQueueLength(ctx context.Context, podIdentity kedav1alpha1.AuthPodIdentity, connectionString, queueName, accountName, endpointSuffix string) (int64, error) {
+func GetAzureQueueLength(ctx context.Context, podIdentity kedav1alpha1.AuthPodIdentity, connectionString, queueName, accountName, endpointSuffix, queueLengthStrategy string) (int64, error) {
 	credential, endpoint, err := ParseAzureStorageQueueConnection(ctx, podIdentity, connectionString, accountName, endpointSuffix)
 	if err != nil {
 		return -1, err
@@ -35,10 +40,41 @@ func GetAzureQueueLength(ctx context.Context, podIdentity kedav1alpha1.AuthPodId
 	serviceURL := azqueue.NewServiceURL(*endpoint, p)
 	queueURL := serviceURL.NewQueueURL(queueName)
 
+	strategy := strings.ToLower(queueLengthStrategy)
+	if strategy == "visibleonly" {
+		visibleMessageCount, err := getVisibleCount(ctx, &queueURL, maxPeekMessages)
+		if err != nil {
+			return -1, err
+		}
+
+		// Queue has less messages than we allowed to peek for, so no need to get the approximation
+		if visibleMessageCount < int64(maxPeekMessages) {
+			return visibleMessageCount, nil
+		}
+
+		props, err := queueURL.GetProperties(ctx)
+		if err != nil {
+			return -1, err
+		}
+
+		return int64(props.ApproximateMessagesCount()), nil
+	}
+
+	// Default strategy (visible + invisible messages)
 	props, err := queueURL.GetProperties(ctx)
 	if err != nil {
 		return -1, err
 	}
 
 	return int64(props.ApproximateMessagesCount()), nil
 }
+
+func getVisibleCount(ctx context.Context, queueURL *azqueue.QueueURL, maxCount int32) (int64, error) {
+	messagesURL := queueURL.NewMessagesURL()
+	queue, err := messagesURL.Peek(ctx, maxCount)
+	if err != nil {
+		return 0, err
+	}
+	num := queue.NumMessages()
+	return int64(num), nil
+}

pkg/scalers/azure/azure_queue_test.go

@@ -7,34 +7,24 @@ import (
 	"testing"
 
 	kedav1alpha1 "github.com/kedacore/keda/v2/apis/keda/v1alpha1"
+	"github.com/stretchr/testify/assert"
 )
 
 func TestGetQueueLength(t *testing.T) {
-	length, err := GetAzureQueueLength(context.TODO(), kedav1alpha1.AuthPodIdentity{}, "", "queueName", "", "")
-	if length != -1 {
-		t.Error("Expected length to be -1, but got", length)
-	}
-
-	if err == nil {
-		t.Error("Expected error for empty connection string, but got nil")
-	}
-
-	if !errors.Is(err, ErrAzureConnectionStringKeyName) {
-		t.Error("Expected error to contain parsing error message, but got", err.Error())
-	}
-
-	length, err = GetAzureQueueLength(context.TODO(), kedav1alpha1.AuthPodIdentity{}, "DefaultEndpointsProtocol=https;AccountName=name;AccountKey=key==;EndpointSuffix=core.windows.net", "queueName", "", "")
-
-	if length != -1 {
-		t.Error("Expected length to be -1, but got", length)
-	}
-
-	if err == nil {
-		t.Error("Expected error for empty connection string, but got nil")
-	}
-
-	var base64Error base64.CorruptInputError
-	if !errors.As(err, &base64Error) {
-		t.Error("Expected error to contain base64 error message, but got", err.Error())
-	}
+	t.Run("Empty connection string", func(t *testing.T) {
+		length, err := GetAzureQueueLength(context.TODO(), kedav1alpha1.AuthPodIdentity{}, "", "queueName", "", "", "")
+
+		assert.Equal(t, int64(-1), length, "Expected length to be -1")
+		assert.NotNil(t, err, "Expected error for empty connection string")
+		assert.True(t, errors.Is(err, ErrAzureConnectionStringKeyName), "Expected error to contain parsing error message")
+	})
+
+	t.Run("Invalid base64 connection string", func(t *testing.T) {
+		length, err := GetAzureQueueLength(context.TODO(), kedav1alpha1.AuthPodIdentity{}, "DefaultEndpointsProtocol=https;AccountName=name;AccountKey=key==;EndpointSuffix=core.windows.net", "queueName", "", "", "")
+
+		assert.Equal(t, int64(-1), length, "Expected length to be -1")
+		assert.NotNil(t, err, "Expected error for invalid connection string")
+		var base64Error base64.CorruptInputError
+		assert.True(t, errors.As(err, &base64Error), "Expected error to contain base64 error message")
+	})
 }

pkg/scalers/azure_queue_scaler.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"net/http"
 	"strconv"
+	"strings"
 
 	"github.com/go-logr/logr"
 	v2 "k8s.io/api/autoscaling/v2"
@@ -54,6 +55,7 @@ type azureQueueMetadata struct {
 	connection                  string
 	accountName                 string
 	endpointSuffix              string
+	queueLengthStrategy         string
 	triggerIndex                int
 }
 
@@ -120,6 +122,17 @@ 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 == "default" || strategy == "visibleonly" {
+			meta.queueLengthStrategy = strategy
+		} else {
+			return nil, kedav1alpha1.AuthPodIdentity{}, fmt.Errorf("invalid queueLengthStrategy %s given", val)
+		}
+	} else {
+		meta.queueLengthStrategy = "default"
+	}
+
 	// If the Use AAD Pod Identity is not present, or set to "none"
 	// then check for connection string
 	switch config.PodIdentity.Provider {
@@ -179,6 +192,7 @@ func (s *azureQueueScaler) GetMetricsAndActivity(ctx context.Context, metricName
 		s.metadata.queueName,
 		s.metadata.accountName,
 		s.metadata.endpointSuffix,
+		s.metadata.queueLengthStrategy,
 	)
 
 	if err != nil {