fix(prometheus-scaler): AWS signv4 parses region if provided (#5421)

Signed-off-by: Siva Guruvareddiar <[email protected]>
Co-authored-by: Jorge Turrado Ferrero <[email protected]>

CHANGELOG.md

@@ -66,7 +66,7 @@ Here is an overview of all new **experimental** features:
 
 ### Fixes
 
-- **General**: TODO ([#XXX](https://github.com/kedacore/keda/issues/XXX))
+- **Prometheus Scaler**: Fix for missing AWS region from metadata ([#5419](https://github.com/kedacore/keda/issues/5419))
 
 ### Deprecations
 

pkg/scalers/aws/aws_sigv4.go

@@ -40,7 +40,6 @@ import (
 // roundTripper adds custom round tripper to sign requests
 type roundTripper struct {
 	client *amp.Client
-	region string
 }
 
 var (
@@ -60,7 +59,7 @@ func (rt *roundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
 	// "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855" is the sha256 of ""
 	const reqHash = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
 
-	err = rt.client.Options().HTTPSignerV4.SignHTTP(req.Context(), cred, req, reqHash, "aps", rt.region, time.Now())
+	err = rt.client.Options().HTTPSignerV4.SignHTTP(req.Context(), cred, req, reqHash, "aps", rt.client.Options().Region, time.Now())
 	if err != nil {
 		return nil, err
 	}
@@ -75,6 +74,10 @@ func (rt *roundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
 func parseAwsAMPMetadata(config *scalersconfig.ScalerConfig) (*awsConfigMetadata, error) {
 	meta := awsConfigMetadata{}
 
+	if val, ok := config.TriggerMetadata["awsRegion"]; ok && val != "" {
+		meta.awsRegion = val
+	}
+
 	auth, err := GetAwsAuthorization(config.TriggerUniqueKey, config.PodIdentity, config.TriggerMetadata, config.AuthParams, config.ResolvedEnv)
 	if err != nil {
 		return nil, err
@@ -109,7 +112,6 @@ func NewSigV4RoundTripper(config *scalersconfig.ScalerConfig) (http.RoundTripper
 	client := amp.NewFromConfig(*awsCfg, func(o *amp.Options) {})
 	rt := &roundTripper{
 		client: client,
-		region: metadata.awsRegion,
 	}
 
 	return rt, nil