Openstack’s Control plane
Openstack’s control plane nodes are the ones that run the most important
components for the cluster. These components are spread throughout the
control nodes. These control nodes are the frontend to openstack users
The traffic and requests must be spread througout these nodes so that our one controller doesn’t die out due to load.
- Each APIs is bound to an IP address in their respective control nodes.
- Each API is also bound to a VIP address running only on one of the control nodes.
- HAProxy load balances the requests to VIP between all control nodes.
- We don’t load balance requests to mysql’s VIP, but mysql does run in multi-master mode.
- Pacemaker monitors state of each controller to keep voting quorum.
- Pacemaker monitors availability of VIP, then migrates VIP to other controller in case of current primary controller failure.