*`region`: The name of the OSS region in which you would like to store objects (for example `oss-cn-beijing`). For a list of regions, you can look at <http://docs.aliyun.com/#/oss/product-documentation/domain-region>
*`endpoint`: (optional) By default, the endpoint shoulb be `<bucket>.<region>.aliyuncs.com` or `<bucket>.<region>-internal.aliyuncs.com` (when internal=true). You can change the default endpoint via changing this value.
*`internal`: (optional) Using internal endpoint or the public endpoint for OSS access. The default is false. For a list of regions, you can look at <http://docs.aliyun.com/#/oss/product-documentation/domain-region>
*`chunksize`: (optional) The default part size for multipart uploads (performed by WriteStream) to OSS. The default is 10 MB. Keep in mind that the minimum part size for OSS is 5MB. You might experience better performance for larger chunk sizes depending on the speed of your connection to OSS.
*`rootdirectory`: (optional) The root directory tree in which all registry files will be stored. Defaults to the empty string (bucket root).