def _callUpgradeAgent(self, ev_data, failTimeout) -> None:
        """
        Callback which is called when upgrade time come.
        Writes upgrade record to upgrade log and asks
        node control service to perform upgrade

        :param when: upgrade time
        :param version: version to upgrade to
        """

        logger.info("{}'s upgrader calling agent for upgrade".format(self))
        self._actionLog.append_started(ev_data)
        self._action_start_callback()
        self.scheduledAction = None
        asyncio.ensure_future(
            self._sendUpgradeRequest(ev_data, failTimeout))
Callback which is called when upgrade time come.
        Writes upgrade record to upgrade log and asks
        node control service to perform upgrade

        :param when: upgrade time
        :param version: version to upgrade to