def refresh(self, credentials=False):
data = self.datacenter.raw_machine_data(self.id, <EOL>credentials=credentials)<EOL>self._save(data)<EOL>
::

    GET /:login/machines/:id

:param credentials: whether to return machine passwords
:type credentials: :py:class:`bool`

Fetch the existing state and values for the 
:py:class:`smartdc.machine.Machine` from the datacenter and commit the 
values locally.