Setup before the Heat stack create or update has been done.

def _pre_heat_deploy(self):
        """Setup before the Heat stack create or update has been done."""
        clients = self.app.client_manager
        compute_client = clients.compute

        self.log.debug("Checking hypervisor stats")
        if utils.check_hypervisor_stats(compute_client) is None:
            raise exceptions.DeploymentError(
                "Expected hypervisor stats not met")
        return True