def get_config(self, connection_info, disk_info):
        conf = super(LibvirtNFSVolumeDriver,
                     self).get_config(connection_info, disk_info)

        conf.source_type = 'file'
        conf.source_path = connection_info['data']['device_path']
        conf.driver_format = connection_info['data'].get('format', 'raw')
        conf.driver_io = "native"
        return conf
Returns xml for libvirt.
dataset/ETHPy150Open openstack/nova/nova/virt/libvirt/volume/nfs.py/LibvirtNFSVolumeDriver.get_config