[8.x](backport #41572) [aws] Set region in config from GetBucketLocation API call

CHANGELOG.next.asciidoc

@@ -174,6 +174,7 @@ https://github.com/elastic/beats/compare/v8.8.1\...main[Check the HEAD diff]
 - Log bad handshake details when websocket connection fails {pull}41300[41300]
 - Journald input now can read events from all boots {issue}41083[41083] {pull}41244[41244]
 - Fix double encoding of client_secret in the Entity Analytics input's Azure Active Directory provider {pull}41393[41393]
+- Fix aws region in aws-s3 input s3 polling mode.  {pull}41572[41572]
 - Fix errors in SQS host resolution in the `aws-s3` input when using custom (non-AWS) endpoints. {pull}41504[41504]
 - The azure-eventhub input now correctly reports its status to the Elastic Agent on fatal errors {pull}41469[41469]
 

x-pack/filebeat/input/awss3/s3.go

@@ -16,16 +16,16 @@ import (
 	"github.com/elastic/beats/v7/libbeat/beat"
 )
 
-func createS3API(ctx context.Context, config config, awsConfig awssdk.Config) (*awsS3API, error) {
-	s3Client := s3.NewFromConfig(awsConfig, config.s3ConfigModifier)
-	regionName, err := getRegionForBucket(ctx, s3Client, config.getBucketName())
+func (in *s3PollerInput) createS3API(ctx context.Context) (*awsS3API, error) {
+	s3Client := s3.NewFromConfig(in.awsConfig, in.config.s3ConfigModifier)
+	regionName, err := getRegionForBucket(ctx, s3Client, in.config.getBucketName())
 	if err != nil {
 		return nil, fmt.Errorf("failed to get AWS region for bucket: %w", err)
 	}
 	// Can this really happen?
-	if regionName != awsConfig.Region {
-		awsConfig.Region = regionName
-		s3Client = s3.NewFromConfig(awsConfig, config.s3ConfigModifier)
+	if regionName != in.awsConfig.Region {
+		in.awsConfig.Region = regionName
+		s3Client = s3.NewFromConfig(in.awsConfig, in.config.s3ConfigModifier)
 	}
 
 	return newAWSs3API(s3Client), nil

x-pack/filebeat/input/awss3/s3_input.go

@@ -73,7 +73,7 @@ func (in *s3PollerInput) Run(
 	defer in.states.Close()
 
 	ctx := v2.GoContextFromCanceler(inputContext.Cancelation)
-	in.s3, err = createS3API(ctx, in.config, in.awsConfig)
+	in.s3, err = in.createS3API(ctx)
 	if err != nil {
 		return fmt.Errorf("failed to create S3 API: %w", err)
 	}