'Used to enable/disable a service. For compute services, setting to
disabled stops new builds arriving on that host.
:param host_name: the name of the host machine that the service is
running
:param binary: The name of the executable that the service runs as
:param params_to_update: eg. {\'disabled\': True}'

def service_update(self, ctxt, host_name, binary, params_to_update):

    cctxt = self.client.prepare(version='1.7')
    return cctxt.call(ctxt, 'service_update', host_name=host_name, binary=binary, params_to_update=params_to_update)
