Resolve Pub/Sub resources from scale target's environment

CHANGELOG.md

@@ -75,6 +75,7 @@ Here is an overview of all new **experimental** features:
 - **General**: Add `validations.keda.sh/hpa-ownership` annotation to HPA to disable ownership validation ([#5516](https://github.com/kedacore/keda/issues/5516))
 - **General**: Support csv-format for WATCH_NAMESPACE env var ([#5670](https://github.com/kedacore/keda/issues/5670))
 - **Azure Event Hub Scaler**: Remove usage of checkpoint offsets to account for SDK checkpointing implementation changes ([#5574](https://github.com/kedacore/keda/issues/5574))
+- **GCP Pub/Sub Scaler**: Add support for resolving resource names from the scale target's environment ([#5693](https://github.com/kedacore/keda/issues/5693))
 - **GCP Stackdriver Scaler**: Add missing parameters 'rate' and 'count' for GCP Stackdriver Scaler alignment ([#5633](https://github.com/kedacore/keda/issues/5633))
 - **Metrics API Scaler**: Add support for various formats: json, xml, yaml, prometheus ([#2633](https://github.com/kedacore/keda/issues/2633))
 - **MongoDB Scaler**: Add scheme field support srv record ([#5544](https://github.com/kedacore/keda/issues/5544))

pkg/scalers/gcp_pubsub_scaler.go

@@ -71,6 +71,80 @@ func NewPubSubScaler(config *scalersconfig.ScalerConfig) (Scaler, error) {
 	}, nil
 }
 
+func parsePubSubResourceConfig(config *scalersconfig.ScalerConfig, meta *pubsubMetadata) error {
+	sub, subPresent := config.TriggerMetadata["subscriptionName"]
+	subFromEnv, subFromEnvPresent := config.TriggerMetadata["subscriptionNameFromEnv"]
+	if subPresent && subFromEnvPresent {
+		return fmt.Errorf("exactly one of subscriptionName or subscriptionNameFromEnv is allowed")
+	}
+	hasSub := subPresent || subFromEnvPresent
+
+	topic, topicPresent := config.TriggerMetadata["topicName"]
+	topicFromEnv, topicFromEnvPresent := config.TriggerMetadata["topicNameFromEnv"]
+	if topicPresent && topicFromEnvPresent {
+		return fmt.Errorf("exactly one of topicName or topicNameFromEnv is allowed")
+	}
+	hasTopic := topicPresent || topicFromEnvPresent
+
+	if (!hasSub && !hasTopic) || (hasSub && hasTopic) {
+		return fmt.Errorf("exactly one of subscription or topic name must be given")
+	}
+
+	if hasSub {
+		if subPresent {
+			if sub == "" {
+				return fmt.Errorf("no subscription name given")
+			}
+
+			meta.resourceName = sub
+		} else {
+			if subFromEnv == "" {
+				return fmt.Errorf("no environment variable name given for resolving subscription name")
+			}
+
+			resolvedSub, ok := config.ResolvedEnv[subFromEnv]
+			if !ok {
+				return fmt.Errorf("resolved environment doesn't contain name '%s'", subFromEnv)
+			}
+
+			if resolvedSub == "" {
+				return fmt.Errorf("resolved environment subscription name is empty")
+			}
+
+			meta.resourceName = config.ResolvedEnv[subFromEnv]
+		}
+
+		meta.resourceType = resourceTypePubSubSubscription
+	} else {
+		if topicPresent {
+			if topic == "" {
+				return fmt.Errorf("no topic name given")
+			}
+
+			meta.resourceName = topic
+		} else {
+			if topicFromEnv == "" {
+				return fmt.Errorf("no environment variable name given for resolving topic name")
+			}
+
+			resolvedTopic, ok := config.ResolvedEnv[topicFromEnv]
+			if !ok {
+				return fmt.Errorf("resolved environment doesn't contain name '%s'", topicFromEnv)
+			}
+
+			if resolvedTopic == "" {
+				return fmt.Errorf("resolved environment topic name is empty")
+			}
+
+			meta.resourceName = config.ResolvedEnv[topicFromEnv]
+		}
+
+		meta.resourceType = resourceTypePubSubTopic
+	}
+
+	return nil
+}
+
 func parsePubSubMetadata(config *scalersconfig.ScalerConfig, logger logr.Logger) (*pubsubMetadata, error) {
 	meta := pubsubMetadata{mode: pubSubModeSubscriptionSize, value: pubSubDefaultValue}
 
@@ -106,26 +180,9 @@ func parsePubSubMetadata(config *scalersconfig.ScalerConfig, logger logr.Logger)
 
 	meta.aggregation = config.TriggerMetadata["aggregation"]
 
-	sub, subPresent := config.TriggerMetadata["subscriptionName"]
-	topic, topicPresent := config.TriggerMetadata["topicName"]
-	if (!subPresent && !topicPresent) || (subPresent && topicPresent) {
-		return nil, fmt.Errorf("exactly one of subscription or topic name must be given")
-	}
-
-	if subPresent {
-		if sub == "" {
-			return nil, fmt.Errorf("no subscription name given")
-		}
-
-		meta.resourceName = sub
-		meta.resourceType = resourceTypePubSubSubscription
-	} else {
-		if topic == "" {
-			return nil, fmt.Errorf("no topic name given")
-		}
-
-		meta.resourceName = topic
-		meta.resourceType = resourceTypePubSubTopic
+	err := parsePubSubResourceConfig(config, &meta)
+	if err != nil {
+		return nil, err
 	}
 
 	meta.activationValue = 0

pkg/scalers/gcp_pubsub_scaler_test.go

@@ -10,7 +10,9 @@ import (
 )
 
 var testPubSubResolvedEnv = map[string]string{
-	"SAMPLE_CREDS": "{}",
+	"SAMPLE_CREDS":        "{}",
+	"MY_ENV_SUBSCRIPTION": "myEnvSubscription",
+	"MY_ENV_TOPIC":        "myEnvTopic",
 }
 
 type parsePubSubMetadataTestData struct {
@@ -76,6 +78,14 @@ var testPubSubMetadata = []parsePubSubMetadataTestData{
 	{nil, map[string]string{"value": "7", "credentialsFromEnv": "SAMPLE_CREDS"}, true},
 	// both subscriptionSize and topicName present
 	{nil, map[string]string{"subscriptionSize": "7", "topicName": "mytopic", "value": "7", "credentialsFromEnv": "SAMPLE_CREDS"}, true},
+	// both subscriptionName and subscriptionNameFromEnv present
+	{nil, map[string]string{"subscriptionName": "mysubscription", "subscriptionNameFromEnv": "MY_ENV_SUBSCRIPTION", "value": "7", "credentialsFromEnv": "SAMPLE_CREDS"}, true},
+	// both topicName and topicNameFromEnv present
+	{nil, map[string]string{"topicName": "mytopic", "topicNameFromEnv": "MY_ENV_TOPIC", "value": "7", "credentialsFromEnv": "SAMPLE_CREDS"}, true},
+	// subscriptionNameFromEnv present
+	{nil, map[string]string{"subscriptionNameFromEnv": "MY_ENV_SUBSCRIPTION", "value": "7", "credentialsFromEnv": "SAMPLE_CREDS"}, false},
+	// topicNameFromEnv present
+	{nil, map[string]string{"topicNameFromEnv": "MY_ENV_TOPIC", "value": "7", "credentialsFromEnv": "SAMPLE_CREDS"}, false},
 }
 
 var gcpPubSubMetricIdentifiers = []gcpPubSubMetricIdentifier{
@@ -90,6 +100,8 @@ var gcpResourceNameTests = []gcpPubSubSubscription{
 	{&testPubSubMetadata[12], 1, "projects/myproject/mysubscription", ""},
 	{&testPubSubMetadata[17], 1, "mytopic", "myproject"},
 	{&testPubSubMetadata[18], 1, "projects/myproject/mytopic", ""},
+	{&testPubSubMetadata[24], 1, "myEnvSubscription", ""},
+	{&testPubSubMetadata[25], 1, "myEnvTopic", ""},
 }
 
 var gcpSubscriptionDefaults = []gcpPubSubSubscription{
@@ -140,7 +152,7 @@ func TestGcpPubSubGetMetricSpecForScaling(t *testing.T) {
 	}
 }
 
-func TestGcpPubSubSubscriptionName(t *testing.T) {
+func TestGcpPubSubResourceName(t *testing.T) {
 	for _, testData := range gcpResourceNameTests {
 		meta, err := parsePubSubMetadata(&scalersconfig.ScalerConfig{TriggerMetadata: testData.metadataTestData.metadata, ResolvedEnv: testPubSubResolvedEnv, TriggerIndex: testData.triggerIndex}, logr.Discard())
 		if err != nil {
@@ -150,7 +162,7 @@ func TestGcpPubSubSubscriptionName(t *testing.T) {
 		resourceID, projectID := getResourceData(&mockGcpPubSubScaler)
 
 		if resourceID != testData.name || projectID != testData.projectID {
-			t.Error("Wrong Subscription parsing:", resourceID, projectID)
+			t.Error("Wrong Resource parsing:", resourceID, projectID)
 		}
 	}
 }