code: def create_external_store(self, project_name, config):
          
          params = {}
          resource = "/externalstores"
          headers = {"x-log-bodyrawsize": '0', "Content-Type": "application/json"}
  
          body_str = six.b(json.dumps(config.to_json()))
  
          (resp, header) = self._send("POST", project_name, body_str, resource, params, headers)
          return CreateExternalStoreResponse(header, resp)
docs: create log store 
          Unsuccessful opertaion will cause an LogException.
  
          :type project_name: string
          :param project_name: the Project name 
  
          :type config : ExternalStoreConfig
          :param config :external store config
  
  
          :return: CreateExternalStoreResponse
          
          :raise: LogException