Add query parameters in prometheus scaler

CHANGELOG.md

@@ -53,6 +53,7 @@ To learn more about active deprecations, we recommend checking [GitHub Discussio
 - **Governance**: KEDA transitioned to CNCF Graduated project ([#63](https://github.com/kedacore/governance/issues/63))
 
 ### Improvements
+- **General**: Add parameter queryParameters in prometheus-scaler (N/A)
 - **General**: Add more events for user checking ([#796](https://github.com/kedacore/keda/issues/3764))
 - **General**: Add ScaledObject/ScaledJob names to output of `kubectl get triggerauthentication/clustertriggerauthentication` ([#796](https://github.com/kedacore/keda/issues/796))
 - **General**: Add standalone CRD generation to release workflow ([#2726](https://github.com/kedacore/keda/issues/2726))

pkg/scalers/prometheus_scaler.go

@@ -25,6 +25,7 @@ import (
 const (
 	promServerAddress       = "serverAddress"
 	promQuery               = "query"
+	promQueryParameters     = "queryParameters"
 	promThreshold           = "threshold"
 	promActivationThreshold = "activationThreshold"
 	promNamespace           = "namespace"
@@ -48,6 +49,7 @@ type prometheusScaler struct {
 type prometheusMetadata struct {
 	serverAddress       string
 	query               string
+	queryParameters     map[string]string
 	threshold           float64
 	activationThreshold float64
 	prometheusAuth      *authentication.AuthMeta
@@ -151,6 +153,15 @@ func parsePrometheusMetadata(config *ScalerConfig) (meta *prometheusMetadata, er
 		return nil, fmt.Errorf("no %s given", promQuery)
 	}
 
+	if val, ok := config.TriggerMetadata[promQueryParameters]; ok && val != "" {
+		queryParameters, err := kedautil.ParseStringList(val)
+		if err != nil {
+			return nil, fmt.Errorf("error parsing %s: %w", promQueryParameters, err)
+		}
+
+		meta.queryParameters = queryParameters
+	}
+
 	if val, ok := config.TriggerMetadata[promThreshold]; ok && val != "" {
 		t, err := strconv.ParseFloat(val, 64)
 		if err != nil {
@@ -262,6 +273,10 @@ func (s *prometheusScaler) ExecutePromQuery(ctx context.Context) (float64, error
 		url = fmt.Sprintf("%s&namespace=%s", url, s.metadata.namespace)
 	}
 
+	if len(s.metadata.queryParameters) > 0 {
+		url = fmt.Sprintf("%s&%s", url, s.metadata.queryParameters)
+	}
+
 	req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
 	if err != nil {
 		return -1, err