Background

We want to make sure that, when there's a spec change, that the CPMS performs a rolling update as expected.

To simulate this, we will, in presubmits, modify the spec of `master-1`. The CPMS should observe that the spec has changed and create a replacement machine for the master.

Use master-1 so that we know it replaces based on the index and not always starting from 0.

Only replace 1 instance to save on cost/time.

Steps

• Create a test that:
  • Checks the cluster operators are all stable/waits for them to stabilise
  • Checks/creates an active CPMS
  • Checks the cluster operators are all stable/waits for them to stabilise
  • Modify master-1's spec to cause it to be updated
  • Checks that the CPMS creates a new instance
  • Checks naming of the new machine
  • Checks the old machine isn't marked for deletion while the new Machine's phase is not Running
  • Waits until the replacement is complete, ie CPMS status reports replicas == updatedReplicas
  • Waits until cluster operators stabilise again

Stakeholders

• Cluster Infra

Definition of Done

• Test is merged and proves rolling update strategy is working for a single machine

• Docs

• N/A

• Testing

• N/A