Ensure that the LB's nodes matches the stack

def configure_nodes(self):
        """Ensure that the LB's nodes matches the stack"""
        # Since load balancing runs after server provisioning,
        # the servers should already be created regardless of
        # whether this was a preexisting load balancer or not.
        # We also have the existing nodes, because add_to_inventory
        # has been called already
        required_nodes = self._get_required_nodes()

        log.debug(
                "Matching existing lb nodes to required %s (port %s)"
                % (", ".join(required_nodes), self.backend_port)
                )

        self.consul.match_lb_nodes(
            self.lb_attrs[A.loadbalancer.ID],
            self.lb_attrs[A.loadbalancer.NODES_KEY],
            required_nodes,
            self.backend_port)

        self.lb_attrs = self.consul.lb_details(
                self.lb_attrs[A.loadbalancer.ID]
                )