[MM-53881] Make sure export filestore won't use bifrost (#24169)

server/platform/shared/filestore/filesstore.go

@@ -125,10 +125,24 @@ func (settings *FileBackendSettings) CheckMandatoryS3Fields() error {
 	return nil
 }
 
+// NewFileBackend creates a new file backend
 func NewFileBackend(settings FileBackendSettings) (FileBackend, error) {
+	return newFileBackend(settings, true)
+}
+
+// NewExportFileBackend creates a new file backend for exports, that will not attempt to use bifrost.
+func NewExportFileBackend(settings FileBackendSettings) (FileBackend, error) {
+	return newFileBackend(settings, false)
+}
+
+func newFileBackend(settings FileBackendSettings, canBeCloud bool) (FileBackend, error) {
 	switch settings.DriverName {
 	case driverS3:
-		backend, err := NewS3FileBackend(settings)
+		newBackendFn := NewS3FileBackend
+		if !canBeCloud {
+			newBackendFn = NewS3FileBackendWithoutBifrost
+		}
+		backend, err := newBackendFn(settings)
 		if err != nil {
 			return nil, errors.Wrap(err, "unable to connect to the s3 backend")
 		}

server/platform/shared/filestore/s3store.go

@@ -88,8 +88,17 @@ func (s *S3FileBackendNoBucketError) Error() string {
 	return "no such bucket"
 }
 
-// NewS3FileBackend returns an instance of an S3FileBackend.
+// NewS3FileBackend returns an instance of an S3FileBackend and determine if we are in Mattermost cloud or not.
 func NewS3FileBackend(settings FileBackendSettings) (*S3FileBackend, error) {
+	return newS3FileBackend(settings, os.Getenv("MM_CLOUD_FILESTORE_BIFROST") != "")
+}
+
+// NewS3FileBackendWithoutBifrost returns an instance of an S3FileBackend that will not use bifrost.
+func NewS3FileBackendWithoutBifrost(settings FileBackendSettings) (*S3FileBackend, error) {
+	return newS3FileBackend(settings, false)
+}
+
+func newS3FileBackend(settings FileBackendSettings, isCloud bool) (*S3FileBackend, error) {
 	timeout := time.Duration(settings.AmazonS3RequestTimeoutMilliseconds) * time.Millisecond
 	backend := &S3FileBackend{
 		endpoint:       settings.AmazonS3Endpoint,
@@ -106,7 +115,6 @@ func NewS3FileBackend(settings FileBackendSettings) (*S3FileBackend, error) {
 		timeout:        timeout,
 		presignExpires: time.Duration(settings.AmazonS3PresignExpiresSeconds) * time.Second,
 	}
-	isCloud := os.Getenv("MM_CLOUD_FILESTORE_BIFROST") != ""
 	cli, err := backend.s3New(isCloud)
 	if err != nil {
 		return nil, err