From 415288d2ca861f4acb7daafad0f5b23896cea394 Mon Sep 17 00:00:00 2001
From: Ratnadeep Debnath <rtnpro@gmail.com>
Date: Thu, 22 Jul 2021 19:24:05 +0200
Subject: [PATCH] Add suport custom metricName in RabbitMQ scaler

Fixes #1975

Signed-off-by: Ratnadeep Debnath <rtnpro@gmail.com>
---
 CHANGELOG.md                        |  1 +
 pkg/scalers/rabbitmq_scaler.go      | 37 ++++++++++++++++-------------
 pkg/scalers/rabbitmq_scaler_test.go |  3 +++
 3 files changed, 25 insertions(+), 16 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d658344a826..8fbc4c34790 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -29,6 +29,7 @@
 - Introduce Idle Replica Mode ([#1958](https://github.com/kedacore/keda/pull/1958))
 - Add new scaler for Selenium Grid ([#1971](https://github.com/kedacore/keda/pull/1971))
 - Support using regex to select the queues in RabbitMQ Scaler ([#1957](https://github.com/kedacore/keda/pull/1957))
+- Support custom metric name in RabbitMQ Scaler ([#1976](https://github.com/kedacore/keda/pull/1976))
 
 ### Improvements
 
diff --git a/pkg/scalers/rabbitmq_scaler.go b/pkg/scalers/rabbitmq_scaler.go
index dc293c03a21..c62a35d6580 100644
--- a/pkg/scalers/rabbitmq_scaler.go
+++ b/pkg/scalers/rabbitmq_scaler.go
@@ -52,14 +52,15 @@ type rabbitMQScaler struct {
 }
 
 type rabbitMQMetadata struct {
-	queueName string
-	mode      string  // QueueLength or MessageRate
-	value     int     // trigger value (queue length or publish/sec. rate)
-	host      string  // connection string for either HTTP or AMQP protocol
-	protocol  string  // either http or amqp protocol
-	vhostName *string // override the vhost from the connection info
-	useRegex  bool    // specify if the queueName contains a rexeg
-	operation string  // specify the operation to apply in case of multiples queues
+	queueName  string
+	mode       string  // QueueLength or MessageRate
+	value      int     // trigger value (queue length or publish/sec. rate)
+	host       string  // connection string for either HTTP or AMQP protocol
+	protocol   string  // either http or amqp protocol
+	vhostName  *string // override the vhost from the connection info
+	useRegex   bool    // specify if the queueName contains a rexeg
+	operation  string  // specify the operation to apply in case of multiples queues
+	metricName string  // Custom metric name for trigger
 }
 
 type queueInfo struct {
@@ -197,6 +198,17 @@ func parseRabbitMQMetadata(config *ScalerConfig) (*rabbitMQMetadata, error) {
 		return nil, fmt.Errorf("unable to parse trigger: %s", err)
 	}
 
+	// Resolve metricName
+	if val, ok := config.TriggerMetadata["metricName"]; ok {
+		meta.metricName = kedautil.NormalizeString(fmt.Sprintf("%s-%s", "rabbitmq", val))
+	} else {
+		if meta.mode == rabbitModeQueueLength {
+			meta.metricName = kedautil.NormalizeString(fmt.Sprintf("%s-%s", "rabbitmq", meta.queueName))
+		} else {
+			meta.metricName = kedautil.NormalizeString(fmt.Sprintf("%s-%s", "rabbitmq-rate", meta.queueName))
+		}
+	}
+
 	return &meta, nil
 }
 
@@ -383,18 +395,11 @@ func (s *rabbitMQScaler) getQueueInfoViaHTTP() (*queueInfo, error) {
 
 // GetMetricSpecForScaling returns the MetricSpec for the Horizontal Pod Autoscaler
 func (s *rabbitMQScaler) GetMetricSpecForScaling() []v2beta2.MetricSpec {
-	var metricName string
-
-	if s.metadata.mode == rabbitModeQueueLength {
-		metricName = kedautil.NormalizeString(fmt.Sprintf("%s-%s", "rabbitmq", s.metadata.queueName))
-	} else {
-		metricName = kedautil.NormalizeString(fmt.Sprintf("%s-%s", "rabbitmq-rate", s.metadata.queueName))
-	}
 	metricValue := resource.NewQuantity(int64(s.metadata.value), resource.DecimalSI)
 
 	externalMetric := &v2beta2.ExternalMetricSource{
 		Metric: v2beta2.MetricIdentifier{
-			Name: metricName,
+			Name: s.metadata.metricName,
 		},
 		Target: v2beta2.MetricTarget{
 			Type:         v2beta2.AverageValueMetricType,
diff --git a/pkg/scalers/rabbitmq_scaler_test.go b/pkg/scalers/rabbitmq_scaler_test.go
index 65cbb4bd0f5..46befbdf4e2 100644
--- a/pkg/scalers/rabbitmq_scaler_test.go
+++ b/pkg/scalers/rabbitmq_scaler_test.go
@@ -92,11 +92,14 @@ var testRabbitMQMetadata = []parseRabbitMQMetadataTestData{
 	{map[string]string{"mode": "MessageRate", "value": "1000", "queueName": "sample", "host": "http://", "useRegex": "true"}, false, map[string]string{}},
 	// queue length and useRegex
 	{map[string]string{"mode": "QueueLength", "value": "1000", "queueName": "sample", "host": "http://", "useRegex": "true"}, false, map[string]string{}},
+	// custom metric name
+	{map[string]string{"mode": "QueueLength", "value": "1000", "queueName": "sample", "host": "http://", "useRegex": "true", "metricName": "host1-sample"}, false, map[string]string{}},
 }
 
 var rabbitMQMetricIdentifiers = []rabbitMQMetricIdentifier{
 	{&testRabbitMQMetadata[1], "rabbitmq-sample"},
 	{&testRabbitMQMetadata[7], "rabbitmq-namespace-name"},
+	{&testRabbitMQMetadata[31], "rabbitmq-host1-sample"},
 }
 
 func TestRabbitMQParseMetadata(t *testing.T) {