feat(gcp-stackdriver): handling value if no timeseries is return

CHANGELOG.md

@@ -69,6 +69,7 @@ Here is an overview of all new **experimental** features:
 - **General**: Support TriggerAuthentication properties from ConfigMap ([#4830](https://github.com/kedacore/keda/issues/4830))
 - **General**: Use client-side round-robin load balancing for grpc calls ([#5224](https://github.com/kedacore/keda/issues/5224))
 - **GCP pubsub scaler**: Support distribution-valued metrics and metrics from topics ([#5070](https://github.com/kedacore/keda/issues/5070))
+- **GCP stackdriver scaler**: Support valueIfNull parameter ([#5345](https://github.com/kedacore/keda/pull/5345))
 - **Hashicorp Vault**: Add support to get secret that needs write operation (e.g. pki) ([#5067](https://github.com/kedacore/keda/issues/5067))
 - **Hashicorp Vault**: Fix operator panic when spec.hashiCorpVault.credential.serviceAccount is not set ([#4964](https://github.com/kedacore/keda/issues/4964))
 - **Hashicorp Vault**: Fix operator panic when using root token to authenticate to vault server ([#5192](https://github.com/kedacore/keda/issues/5192))

pkg/scalers/gcp_cloud_tasks_scaler.go

@@ -179,5 +179,5 @@ func (s *gcpCloudTasksScaler) getMetrics(ctx context.Context, metricType string)
 
 	// Cloud Tasks metrics are collected every 60 seconds so no need to aggregate them.
 	// See: https://cloud.google.com/monitoring/api/metrics_gcp#gcp-cloudtasks
-	return s.client.GetMetrics(ctx, filter, s.metadata.projectID, nil)
+	return s.client.GetMetrics(ctx, filter, s.metadata.projectID, nil, nil)
 }

pkg/scalers/gcp_stackdriver_client.go

@@ -213,7 +213,8 @@ func (s StackDriverClient) GetMetrics(
 	ctx context.Context,
 	filter string,
 	projectID string,
-	aggregation *monitoringpb.Aggregation) (float64, error) {
+	aggregation *monitoringpb.Aggregation,
+	valueIfNull *float64) (float64, error) {
 	// Set the start time to 1 minute ago
 	startTime := time.Now().UTC().Add(time.Minute * -2)
 
@@ -246,7 +247,10 @@ func (s StackDriverClient) GetMetrics(
 	resp, err := it.Next()
 
 	if err == iterator.Done {
-		return value, fmt.Errorf("could not find stackdriver metric with filter %s", filter)
+		if valueIfNull == nil {
+			return value, fmt.Errorf("could not find stackdriver metric with filter %s", filter)
+		}
+		return *valueIfNull, nil
 	}
 
 	if err != nil {

pkg/scalers/gcp_stackdriver_scaler.go

@@ -30,6 +30,7 @@ type stackdriverMetadata struct {
 	targetValue           float64
 	activationTargetValue float64
 	metricName            string
+	valueIfNull           *float64
 
 	gcpAuthorization *gcpAuthorizationMetadata
 	aggregation      *monitoringpb.Aggregation
@@ -109,6 +110,14 @@ func parseStackdriverMetadata(config *ScalerConfig, logger logr.Logger) (*stackd
 		meta.activationTargetValue = activationTargetValue
 	}
 
+	if val, ok := config.TriggerMetadata["valueIfNull"]; ok && val != "" {
+		valueIfNull, err := strconv.ParseFloat(val, 64)
+		if err != nil {
+			return nil, fmt.Errorf("valueIfNull parsing error %w", err)
+		}
+		meta.valueIfNull = &valueIfNull
+	}
+
 	auth, err := getGCPAuthorization(config)
 	if err != nil {
 		return nil, err
@@ -207,7 +216,7 @@ func (s *stackdriverScaler) GetMetricsAndActivity(ctx context.Context, metricNam
 
 // getMetrics gets metric type value from stackdriver api
 func (s *stackdriverScaler) getMetrics(ctx context.Context) (float64, error) {
-	val, err := s.client.GetMetrics(ctx, s.metadata.filter, s.metadata.projectID, s.metadata.aggregation)
+	val, err := s.client.GetMetrics(ctx, s.metadata.filter, s.metadata.projectID, s.metadata.aggregation, s.metadata.valueIfNull)
 	if err == nil {
 		s.logger.V(1).Info(
 			fmt.Sprintf("Getting metrics for project %s, filter %s and aggregation %v. Result: %f",

pkg/scalers/gcp_stackdriver_scaler_test.go

@@ -55,6 +55,10 @@ var testStackdriverMetadata = []parseStackdriverMetadataTestData{
 	{nil, map[string]string{"projectId": "myProject", "filter": sdFilter, "credentialsFromEnv": "SAMPLE_CREDS", "alignmentPeriodSeconds": "a"}, true},
 	// properly formed float targetValue and activationTargetValue
 	{nil, map[string]string{"projectId": "myProject", "filter": sdFilter, "credentialsFromEnv": "SAMPLE_CREDS", "targetValue": "1.1", "activationTargetValue": "2.1"}, false},
+	// properly formed float valueIfNull
+	{nil, map[string]string{"projectId": "myProject", "filter": sdFilter, "credentialsFromEnv": "SAMPLE_CREDS", "targetValue": "1.1", "activationTargetValue": "2.1", "valueIfNull": "1.0"}, false},
+	// With bad valueIfNull
+	{nil, map[string]string{"projectId": "myProject", "filter": sdFilter, "credentialsFromEnv": "SAMPLE_CREDS", "targetValue": "1.1", "activationTargetValue": "2.1", "valueIfNull": "toto"}, true},
 }
 
 var gcpStackdriverMetricIdentifiers = []gcpStackdriverMetricIdentifier{