docs: def image_export(self, image_name, dest_url, remote_host=None):
          """Export the specific image to remote host or local file system
          :param image_name: image name that can be uniquely identify an image
          :param dest_path: the location to store exported image, eg.
          /opt/images, the image will be stored in folder
           /opt/images/
          :param remote_host: the server that export image to, the format is
           username@IP eg. nova@192.168.99.1, if remote_host is
          None, it means the image will be stored in local server
          :returns a dictionary that contains the exported image info
          {
           'image_name': the image_name that exported
           'image_path': the image_path after exported
           'os_version': the os version of the exported image
           'md5sum': the md5sum of the original image
          }
          """
          image_info = self._ImageDbOperator.image_query_record(image_name)
          if not image_info:
              msg = ("The image %s does not exist in image repository"
                        % image_name)
              LOG.error(msg)
              raise exception.SDKImageOperationError(rs=20, img=image_name)
  
          image_type = image_info[0]['type']
          # TODO: (nafei) according to image_type, detect image exported path
          # For multiple disk image, make the tgz firstly, the specify the
          # source_path to be something like: 0100-0101-0102.tgz
          if image_type == 'rootonly':
              source_path = '/'.join([CONF.image.sdk_image_repository,
                                 const.IMAGE_TYPE['DEPLOY'],
                                 image_info[0]['imageosdistro'],
                                 image_name,
                                 CONF.zvm.user_root_vdev])
          else:
              pass
  
          self._scheme2backend(urlparse.urlparse(dest_url).scheme).image_export(
                                                      source_path, dest_url,
                                                      remote_host=remote_host)
  
          # TODO: (nafei) for multiple disks image, update the expect_dict
          # to be the tgz's md5sum
          export_dict = {'image_name': image_name,
                         'image_path': dest_url,
                         'os_version': image_info[0]['imageosdistro'],
                         'md5sum': image_info[0]['md5sum']}
          LOG.info("Image %s export successfully" % image_name)
          return export_dict