get source code and run:
python setup.py install

alioss configrations:
    * storage: specify the storage to use, should be alwasy alioss 
    * storage_path: specify the path prefix in the oss bucket
    * oss_bucket: specify the bucket where you want to store these images for your registry
    * oss_accessid: the access id for the oss bucket, which you get from aliyun.com
    * oss_accesskey: the access key for the oss bucket, which you get from aliyun.com
    * oss_host: oss host, typically, you don't need to care about it. In case that you need to use this registry with internal ip, you may need to change it.
example <you can copy this example into your config.yml, and modify it accordingly>:
oss: &oss
    <<: *common
    storage: alioss
    storage_path: _env:STORAGE_PATH:/devregistry/
    oss_bucket: _env:OSS_BUCKET[:default_value]
    oss_accessid: _env:OSS_KEY[:your_access_id]
    oss_accesskey: _env:OSS_SECRET[:your_access_key]
    oss_host: _env:OSS_HOST[:your_oss_host]

* if you run docker-registry on your local host, export these configurations if you want to modify the default value in the configured in the config.yml:
    export SETTINGS_FLAVOR=oss
    export STORAGE_PATH=<the prefix of the storage path>
    export OSS_BUCKET=<your oss bucket>
    export OSS_KEY=<your access id>
    export OSS_SECRET=<your access key>
    export OSS_HOST=<your oss host>
* if you run docker-registry on your docker container, remmeber to specify these settings as cmd args:
    docker run \
     -e SETTINGS_FLAVOR=oss \
     -e STORAGE_PATH=/dockerregistry/ \
     -e OSS_BUCKET=docker-registry \
     -e OSS_KEY=<your access id> \
     -e OSS_SECRET=<your access key> \
     -e OSS_HOST=<your oss host> \
     -e SEARCH_BACKEND=sqlalchemy \
     -p 5000:5000 \
     registry