feat: Add activationTarget for formulas

CHANGELOG.md

@@ -58,7 +58,7 @@ To learn more about active deprecations, we recommend checking [GitHub Discussio
 
 Here is an overview of all new **experimental** features:
 
-- **General**: Add support for formula based evaluation of metric values ([#2440](https://github.com/kedacore/keda/issues/2440))
+- **General**: Add support for formula based evaluation of metric values ([#2440](https://github.com/kedacore/keda/issues/2440)|[#4998](https://github.com/kedacore/keda/pull/4998))
 
 ### Improvements
 - **General**: Add apiserver Prometheus metrics to KEDA Metric Server ([#4460](https://github.com/kedacore/keda/issues/4460))

apis/keda/v1alpha1/scaledobject_types.go

@@ -117,6 +117,10 @@ type AdvancedConfig struct {
 type ScalingModifiers struct {
 	Formula string `json:"formula,omitempty"`
 	Target  string `json:"target,omitempty"`
+	// +optional
+	ActivationTarget string `json:"activationTarget,omitempty"`
+	// +optional
+	MetricType autoscalingv2.MetricTargetType `json:"metricType,omitempty"`
 }
 
 // HorizontalPodAutoscalerConfig specifies horizontal scale config

apis/keda/v1alpha1/scaledobject_webhook.go

@@ -392,31 +392,7 @@ func validateScalingModifiersTarget(so *ScaledObject) error {
 		return fmt.Errorf("error converting target for scalingModifiers (string->float) to valid target: %w", err)
 	}
 
-	// if target is given, composite-scaler will be passed to HPA -> all types
-	// need to be the same - make sure all metrics are of the same metricTargetType
-
-	var trigType autoscalingv2.MetricTargetType
-
-	// gauron99: possible TODO: more sofisticated check for trigger could be used here
-	// as well if solution is found (check just the right triggers that are used)
-	for _, trig := range so.Spec.Triggers {
-		if trig.Type == cpuString || trig.Type == memoryString || trig.Name == "" {
-			continue
-		}
-		var current autoscalingv2.MetricTargetType
-		if trig.MetricType == "" {
-			current = autoscalingv2.AverageValueMetricType // default is AverageValue
-		} else {
-			current = trig.MetricType
-		}
-		if trigType == "" {
-			trigType = current
-		} else if trigType != current {
-			err := fmt.Errorf("error trigger types are not the same for composite scaler: %s & %s", trigType, current)
-			return err
-		}
-	}
-	if trigType == autoscalingv2.UtilizationMetricType {
+	if so.Spec.Advanced.ScalingModifiers.MetricType == autoscalingv2.UtilizationMetricType {
 		err := fmt.Errorf("error trigger type is Utilization, but it needs to be AverageValue or Value for external metrics")
 		return err
 	}

config/crd/bases/keda.sh_scaledobjects.yaml

@@ -207,8 +207,15 @@ spec:
                     description: ScalingModifiers describes advanced scaling logic
                       options like formula
                     properties:
+                      activationTarget:
+                        type: string
                       formula:
                         type: string
+                      metricType:
+                        description: MetricTargetType specifies the type of metric
+                          being targeted, and should be either "Value", "AverageValue",
+                          or "Utilization"
+                        type: string
                       target:
                         type: string
                     type: object

controllers/keda/hpa.go

@@ -258,19 +258,12 @@ func (r *ScaledObjectReconciler) getScaledObjectMetricSpecs(ctx context.Context,
 		validNumTarget, _ := strconv.ParseFloat(scaledObject.Spec.Advanced.ScalingModifiers.Target, 64)
 
 		// check & get metric specs type
-		var validMetricType autoscalingv2.MetricTargetType
-		for _, metric := range metricSpecs {
-			if metric.External == nil {
-				continue
-			}
-			if validMetricType == "" {
-				validMetricType = metric.External.Target.Type
-			} else if metric.External.Target.Type != validMetricType {
-				err := fmt.Errorf("error metric target type is not the same for composite scaler: %s & %s", validMetricType, metric.External.Target.Type)
-				return nil, err
-			}
+		metricType := autoscalingv2.AverageValueMetricType
+		if scaledObject.Spec.Advanced.ScalingModifiers.MetricType != "" {
+			metricType = scaledObject.Spec.Advanced.ScalingModifiers.MetricType
 		}
-		if validMetricType == autoscalingv2.UtilizationMetricType {
+
+		if metricType == autoscalingv2.UtilizationMetricType {
 			err := fmt.Errorf("error metric target type is Utilization, but it needs to be AverageValue or Value for external metrics")
 			return nil, err
 		}
@@ -280,11 +273,11 @@ func (r *ScaledObjectReconciler) getScaledObjectMetricSpecs(ctx context.Context,
 			quan := resource.NewMilliQuantity(int64(validNumTarget*1000), resource.DecimalSI)
 
 			correctHpaTarget := autoscalingv2.MetricTarget{
-				Type: validMetricType,
+				Type: metricType,
 			}
-			if validMetricType == autoscalingv2.AverageValueMetricType {
+			if metricType == autoscalingv2.AverageValueMetricType {
 				correctHpaTarget.AverageValue = quan
-			} else if validMetricType == autoscalingv2.ValueMetricType {
+			} else if metricType == autoscalingv2.ValueMetricType {
 				correctHpaTarget.Value = quan
 			}
 			compMetricName := kedav1alpha1.CompositeMetricName

pkg/eventreason/eventreason.go

@@ -50,6 +50,9 @@ const (
 	// KEDAScalerFailed is for event when a scaler fails for a ScaledJob or a ScaledObject
 	KEDAScalerFailed = "KEDAScalerFailed"
 
+	// KEDAMetricSourceFailed is for event when a scaler fails as metric source for custom formula
+	KEDAMetricSourceFailed = "KEDAMetricSourceFailed"
+
 	// KEDAScaleTargetActivated is for event when the scale target of ScaledObject was activated
 	KEDAScaleTargetActivated = "KEDAScaleTargetActivated"
 

pkg/scalers/arangodb_scaler.go

@@ -155,7 +155,11 @@ func parseArangoDBMetadata(config *ScalerConfig) (*arangoDBMetadata, error) {
 		}
 		meta.queryValue = queryValue
 	} else {
-		return nil, fmt.Errorf("no queryValue given")
+		if config.AsMetricSource {
+			meta.queryValue = 0
+		} else {
+			return nil, fmt.Errorf("no queryValue given")
+		}
 	}
 
 	meta.activationQueryValue = 0

pkg/scalers/aws_dynamodb_scaler.go

@@ -152,7 +152,11 @@ func parseAwsDynamoDBMetadata(config *ScalerConfig) (*awsDynamoDBMetadata, error
 
 		meta.targetValue = n
 	} else {
-		return nil, ErrAwsDynamoNoTargetValue
+		if config.AsMetricSource {
+			meta.targetValue = 0
+		} else {
+			return nil, ErrAwsDynamoNoTargetValue
+		}
 	}
 
 	if val, ok := config.TriggerMetadata["activationTargetValue"]; ok && val != "" {

pkg/scalers/azure_app_insights_scaler.go

@@ -79,7 +79,11 @@ func parseAzureAppInsightsMetadata(config *ScalerConfig, logger logr.Logger) (*a
 
 	val, err := getParameterFromConfig(config, azureAppInsightsTargetValueName, false)
 	if err != nil {
-		return nil, err
+		if config.AsMetricSource {
+			meta.targetValue = 0
+		} else {
+			return nil, err
+		}
 	}
 	targetValue, err := strconv.ParseFloat(val, 64)
 	if err != nil {

pkg/scalers/azure_log_analytics_scaler.go

@@ -182,7 +182,11 @@ func parseAzureLogAnalyticsMetadata(config *ScalerConfig) (*azureLogAnalyticsMet
 	// Getting threshold, observe that we don't check AuthParams for threshold
 	val, err := getParameterFromConfig(config, "threshold", false)
 	if err != nil {
-		return nil, err
+		if config.AsMetricSource {
+			val = "0"
+		} else {
+			return nil, err
+		}
 	}
 	threshold, err := strconv.ParseFloat(val, 64)
 	if err != nil {

pkg/scalers/azure_monitor_scaler.go

@@ -87,7 +87,11 @@ func parseAzureMonitorMetadata(config *ScalerConfig, logger logr.Logger) (*azure
 		}
 		meta.targetValue = targetValue
 	} else {
-		return nil, fmt.Errorf("no targetValue given")
+		if config.AsMetricSource {
+			meta.targetValue = 0
+		} else {
+			return nil, fmt.Errorf("no targetValue given")
+		}
 	}
 
 	if val, ok := config.TriggerMetadata[activationTargetValueName]; ok && val != "" {

pkg/scalers/cassandra_scaler.go

@@ -82,7 +82,11 @@ func parseCassandraMetadata(config *ScalerConfig) (*CassandraMetadata, error) {
 		}
 		meta.targetQueryValue = targetQueryValue
 	} else {
-		return nil, fmt.Errorf("no targetQueryValue given")
+		if config.AsMetricSource {
+			meta.targetQueryValue = 0
+		} else {
+			return nil, fmt.Errorf("no targetQueryValue given")
+		}
 	}
 
 	meta.activationTargetQueryValue = 0

pkg/scalers/couchdb_scaler.go

@@ -114,7 +114,11 @@ func parseCouchDBMetadata(config *ScalerConfig) (*couchDBMetadata, string, error
 		}
 		meta.queryValue = queryValue
 	} else {
-		return nil, "", fmt.Errorf("no queryValue given")
+		if config.AsMetricSource {
+			meta.queryValue = 0
+		} else {
+			return nil, "", fmt.Errorf("no queryValue given")
+		}
 	}
 
 	meta.activationQueryValue = 0

pkg/scalers/datadog_scaler.go

@@ -143,7 +143,11 @@ func parseDatadogMetadata(config *ScalerConfig, logger logr.Logger) (*datadogMet
 		}
 		meta.queryValue = queryValue
 	} else {
-		return nil, fmt.Errorf("no queryValue given")
+		if config.AsMetricSource {
+			meta.queryValue = 0
+		} else {
+			return nil, fmt.Errorf("no queryValue given")
+		}
 	}
 
 	if val, ok := config.TriggerMetadata["queryAggregator"]; ok && val != "" {

pkg/scalers/elasticsearch_scaler.go

@@ -199,7 +199,11 @@ func parseElasticsearchMetadata(config *ScalerConfig) (*elasticsearchMetadata, e
 
 	targetValueString, err := GetFromAuthOrMeta(config, "targetValue")
 	if err != nil {
-		return nil, err
+		if config.AsMetricSource {
+			targetValueString = "0"
+		} else {
+			return nil, err
+		}
 	}
 	targetValue, err := strconv.ParseFloat(targetValueString, 64)
 	if err != nil {

pkg/scalers/gcp_cloud_tasks_scaler.go

@@ -73,7 +73,6 @@ func parseGcpCloudTasksMetadata(config *ScalerConfig) (*gcpCloudTaskMetadata, er
 		if val == "" {
 			return nil, fmt.Errorf("no queue name given")
 		}
-
 		meta.queueName = val
 	} else {
 		return nil, fmt.Errorf("no queue name given")

pkg/scalers/influxdb_scaler.go

@@ -131,7 +131,11 @@ func parseInfluxDBMetadata(config *ScalerConfig) (*influxDBMetadata, error) {
 		}
 		thresholdValue = value
 	} else {
-		return nil, fmt.Errorf("no threshold value given")
+		if config.AsMetricSource {
+			thresholdValue = 0
+		} else {
+			return nil, fmt.Errorf("no threshold value given")
+		}
 	}
 	unsafeSsl = false
 	if val, ok := config.TriggerMetadata["unsafeSsl"]; ok {

pkg/scalers/kubernetes_workload_scaler.go

@@ -73,7 +73,11 @@ func parseWorkloadMetadata(config *ScalerConfig) (*kubernetesWorkloadMetadata, e
 	meta.podSelector = podSelector
 	value, err := strconv.ParseFloat(config.TriggerMetadata[valueKey], 64)
 	if err != nil || value == 0 {
-		return nil, fmt.Errorf("value must be a float greater than 0")
+		if config.AsMetricSource {
+			value = 0
+		} else {
+			return nil, fmt.Errorf("value must be a float greater than 0")
+		}
 	}
 	meta.value = value
 

pkg/scalers/loki_scaler.go

@@ -110,7 +110,11 @@ func parseLokiMetadata(config *ScalerConfig) (meta *lokiMetadata, err error) {
 
 		meta.threshold = t
 	} else {
-		return nil, fmt.Errorf("no %s given", lokiThreshold)
+		if config.AsMetricSource {
+			meta.threshold = 0
+		} else {
+			return nil, fmt.Errorf("no %s given", lokiThreshold)
+		}
 	}
 
 	meta.activationThreshold = 0

pkg/scalers/metrics_api_scaler.go

@@ -114,7 +114,11 @@ func parseMetricsAPIMetadata(config *ScalerConfig) (*metricsAPIScalerMetadata, e
 		}
 		meta.targetValue = targetValue
 	} else {
-		return nil, fmt.Errorf("no targetValue given in metadata")
+		if config.AsMetricSource {
+			meta.targetValue = 0
+		} else {
+			return nil, fmt.Errorf("no targetValue given in metadata")
+		}
 	}
 
 	meta.activationTargetValue = 0

pkg/scalers/mongo_scaler.go

@@ -131,7 +131,11 @@ func parseMongoDBMetadata(config *ScalerConfig) (*mongoDBMetadata, string, error
 		}
 		meta.queryValue = queryValue
 	} else {
-		return nil, "", fmt.Errorf("no queryValue given")
+		if config.AsMetricSource {
+			meta.queryValue = 0
+		} else {
+			return nil, "", fmt.Errorf("no queryValue given")
+		}
 	}
 
 	meta.activationQueryValue = 0

pkg/scalers/mssql_scaler.go

@@ -113,7 +113,11 @@ func parseMSSQLMetadata(config *ScalerConfig) (*mssqlMetadata, error) {
 		}
 		meta.targetValue = targetValue
 	} else {
-		return nil, ErrMsSQLNoTargetValue
+		if config.AsMetricSource {
+			meta.targetValue = 0
+		} else {
+			return nil, ErrMsSQLNoTargetValue
+		}
 	}
 
 	// Activation target value

pkg/scalers/mysql_scaler.go

@@ -78,7 +78,11 @@ func parseMySQLMetadata(config *ScalerConfig) (*mySQLMetadata, error) {
 		}
 		meta.queryValue = queryValue
 	} else {
-		return nil, fmt.Errorf("no queryValue given")
+		if config.AsMetricSource {
+			meta.queryValue = 0
+		} else {
+			return nil, fmt.Errorf("no queryValue given")
+		}
 	}
 
 	meta.activationQueryValue = 0

pkg/scalers/newrelic_scaler.go

@@ -116,7 +116,11 @@ func parseNewRelicMetadata(config *ScalerConfig, logger logr.Logger) (*newrelicM
 		}
 		meta.threshold = t
 	} else {
-		return nil, fmt.Errorf("missing %s value", threshold)
+		if config.AsMetricSource {
+			meta.threshold = 0
+		} else {
+			return nil, fmt.Errorf("missing %s value", threshold)
+		}
 	}
 
 	meta.activationThreshold = 0

pkg/scalers/postgresql_scaler.go

@@ -73,7 +73,11 @@ func parsePostgreSQLMetadata(config *ScalerConfig) (*postgreSQLMetadata, error)
 		}
 		meta.targetQueryValue = targetQueryValue
 	} else {
-		return nil, fmt.Errorf("no targetQueryValue given")
+		if config.AsMetricSource {
+			meta.targetQueryValue = 0
+		} else {
+			return nil, fmt.Errorf("no targetQueryValue given")
+		}
 	}
 
 	meta.activationTargetQueryValue = 0

pkg/scalers/predictkube_scaler.go

@@ -405,7 +405,11 @@ func parsePredictKubeMetadata(config *ScalerConfig) (result *predictKubeMetadata
 		}
 		meta.threshold = threshold
 	} else {
-		return nil, fmt.Errorf("no threshold given")
+		if config.AsMetricSource {
+			meta.threshold = 0
+		} else {
+			return nil, fmt.Errorf("no threshold given")
+		}
 	}
 
 	meta.activationThreshold = 0

pkg/scalers/prometheus_scaler.go

@@ -159,7 +159,11 @@ func parsePrometheusMetadata(config *ScalerConfig) (meta *prometheusMetadata, er
 
 		meta.threshold = t
 	} else {
-		return nil, fmt.Errorf("no %s given", promThreshold)
+		if config.AsMetricSource {
+			meta.threshold = 0
+		} else {
+			return nil, fmt.Errorf("no %s given", promThreshold)
+		}
 	}
 
 	meta.activationThreshold = 0

pkg/scalers/scaler.go

@@ -99,6 +99,9 @@ type ScalerConfig struct {
 
 	// MetricType
 	MetricType v2.MetricTargetType
+
+	// When we use the scaler for composite scaler, we shouldn't require the value because it'll be ignored
+	AsMetricSource bool
 }
 
 var (