[Flow Aggregator] Determine bucket region in S3 uploader (#4237)

We determine the region programmatically in the S3 uploader, using the
region "hint" provided in the config.
Before this change, there was a mismatch between the description of the
"region" config parameter and its actual implementation in the S3
uploader.

Signed-off-by: Antonin Bas <[email protected]>

pkg/flowaggregator/clickhouseclient/clickhouseclient.go

@@ -88,11 +88,7 @@ const (
 )
 
 // PrepareClickHouseConnection is used for unit testing
-var (
-	PrepareClickHouseConnection = func(input ClickHouseInput) (string, *sql.DB, error) {
-		return PrepareConnection(input)
-	}
-)
+var PrepareClickHouseConnection = prepareConnection
 
 type stopPayload struct {
 	flushQueue bool
@@ -380,7 +376,7 @@ func (ch *ClickHouseExportProcess) pushRecordsToFrontOfQueue(records []*flowreco
 	}
 }
 
-func PrepareConnection(input ClickHouseInput) (string, *sql.DB, error) {
+func prepareConnection(input ClickHouseInput) (string, *sql.DB, error) {
 	dsn, err := input.GetDataSourceName()
 	if err != nil {
 		return "", nil, fmt.Errorf("error when parsing ClickHouse DSN: %v", err)

pkg/flowaggregator/exporter/s3_test.go

@@ -15,6 +15,7 @@
 package exporter
 
 import (
+	"context"
 	"testing"
 	"time"
 
@@ -28,6 +29,13 @@ import (
 )
 
 func TestS3_UpdateOptions(t *testing.T) {
+	GetS3BucketRegionSaved := s3uploader.GetS3BucketRegion
+	s3uploader.GetS3BucketRegion = func(ctx context.Context, bucket string, regionHint string) (string, error) {
+		return "us-west-2", nil
+	}
+	defer func() {
+		s3uploader.GetS3BucketRegion = GetS3BucketRegionSaved
+	}()
 	compress := true
 	opt := &options.Options{
 		Config: &flowaggregator.FlowAggregatorConfig{

pkg/flowaggregator/s3uploader/s3uploader.go

@@ -40,6 +40,9 @@ const (
 	maxNumBuffersPendingUpload = 5
 )
 
+// GetS3BucketRegion is used for unit testing
+var GetS3BucketRegion = getBucketRegion
+
 type stopPayload struct {
 	flushQueue bool
 }
@@ -100,22 +103,45 @@ func (u *S3Uploader) Upload(ctx context.Context, input *s3.PutObjectInput, awsS3
 	return awsS3Uploader.Upload(ctx, input, opts...)
 }
 
+// getBucketRegion determines the exact region in which the bucket is
+// located. regionHint can be any region in the same partition as the one in
+// which the bucket is located.
+func getBucketRegion(ctx context.Context, bucket string, regionHint string) (string, error) {
+	awsCfg, err := awsconfig.LoadDefaultConfig(ctx, awsconfig.WithRegion(regionHint))
+	if err != nil {
+		return "", fmt.Errorf("unable to load AWS SDK config: %w", err)
+
+	}
+	s3Client := s3.NewFromConfig(awsCfg)
+	bucketRegion, err := s3manager.GetBucketRegion(ctx, s3Client, bucket)
+	if err != nil {
+		return "", fmt.Errorf("unable to determine region for bucket '%s', make sure the bucket exists and set the region parameter appropriately: %w", bucket, err)
+	}
+	return bucketRegion, err
+}
+
 func NewS3UploadProcess(input S3Input, clusterUUID string) (*S3UploadProcess, error) {
 	config := input.Config
-	cfg, err := awsconfig.LoadDefaultConfig(context.TODO(), awsconfig.WithRegion(config.Region))
+	region, err := GetS3BucketRegion(context.TODO(), config.BucketName, config.Region)
+	if err != nil {
+		return nil, err
+	}
+	klog.InfoS("S3 bucket region successfully determined for flow upload", "bucket", config.BucketName, "region", region)
+	awsCfg, err := awsconfig.LoadDefaultConfig(context.TODO(), awsconfig.WithRegion(region))
 	if err != nil {
 		return nil, fmt.Errorf("error when loading AWS config: %w", err)
 	}
-	awsS3Client := s3.NewFromConfig(cfg)
+	awsS3Client := s3.NewFromConfig(awsCfg)
 	awsS3Uploader := s3manager.NewUploader(awsS3Client)
+
 	buf := &bytes.Buffer{}
 	// #nosec G404: random number generator not used for security purposes
 	nameRand := rand.New(rand.NewSource(time.Now().UnixNano()))
 
 	s3ExportProcess := &S3UploadProcess{
 		bucketName:       config.BucketName,
 		bucketPrefix:     config.BucketPrefix,
-		region:           config.Region,
+		region:           region,
 		compress:         *config.Compress,
 		maxRecordPerFile: config.MaxRecordsPerFile,
 		uploadInterval:   input.UploadInterval,