Currently the vertical scaling feature relies on machine deletion hooks provided by the Machine API to scale up and scale down control-plane machines.
The ControlPlaneMachineSetOperator is also required to manage the deletion and creation of machines.

In environments where we have User Provisioned Infrastructure UPI and a non-functional Machine API, the scale-up and scale-down is more manual and users are expected to manually add an remove machines and members.

See for background: https://github.com/openshift/enhancements/blob/master/enhancements/etcd/protecting-etcd-quorum-during-control-plane-scaling.md#non-functional-machine-api-scenarios

For UPI or baremetal scenarios we have documented the following steps:
https://docs.openshift.com/container-platform/4.13/backup_and_restore/control_plane_backup_and_restore/replacing-unhealthy-etcd-member.html#restore-replace-stopped-baremetal-etcd-member_replacing-unhealthy-etcd-member

However in step 4 and onwards it relies on using the machine API to provision a new machine.

If you are running installer-provisioned infrastructure, or you used the Machine API to create your machines, follow these steps. Otherwise, you must create the new control plane node using the same method that was used to originally create it.

The goal of this story is to test out the steps for vertical scaling for an environment when the Machine API is not available and outline the full steps to provision and remove a node to replace an unhealthy member.