Add support for generating a signed URL for downloading a file from the daemon

app/Models/Backup.php

@@ -26,6 +26,9 @@ class Backup extends Model
 
     const RESOURCE_NAME = 'backup';
 
+    const DISK_LOCAL = 'local';
+    const DISK_AWS_S3 = 's3';
+
     /**
      * @var string
      */