Hello

I have two questions about deploying openstack in high available setup

Specifically, HA setup for controller nodes

1. Are openstack services (being deployed on controller nodes) stateless?

Aside from non-openstack packages(galera/mysql, zeromq, ...) for infrastructure, are openstack services stateless?

For example, can I achieve high availability by deploying two nova-api services to two separate controller nodes

by load balacing API calls to them through HAproxy?

Is this(load balancer) the way how openstack achieves high availability?

2. Why minimum 3 controller nodes for HA?

Is this solely due to etcd?

Thanks!