User Story

As a developer of OpenShift I want to make sure machineset selectors are immutable so that customers can't accidentally create a MachineSet which leaks machines

Background

We fixed this issue initially with a webhook implementation https://github.com/openshift/machine-api-operator/pull/944

However, once we have immutability support within CRDs, we should evaluate whether or not this is worth moving from the webhook over to the CRD immutability support.

CRD immutability support will be more reliable as it is implemented by the API server rather than an extension webhook.

Steps

• Work out if we want to replace the webhook immutability with CRD immutability (check parity of the feature, is it more or less identical?)

Stakeholders

• Cluster infra

Definition of Done

• Make a decision about whether to move to CRD immutability
• If yes, add the CRD immutability and remove the webhook immutability

• Docs

• N/A

• Testing

• Standard regression testing