[kolla] [train] haproxy and controller restart causes user impact

We have our haproxy and controller nodes on KVM hosts. When those KVM hosts are restarted, customers who are building or deleting VMs see impact. VMs may go into error status, fail to get DNS records, fail to delete, etc. The obvious reason is because traffic that is being routed to the haproxy on the restarting KVM is lost. If we manually fail over haproxy before restarting the KVM, will that be sufficient to stop traffic being lost, or do we also need to do something with the controller?