Idempotence: An External Patch Extension must only return patches if changes to the templates are required, i.e. unnecessary patches when the template is already in the desired state must be avoided.
-- https://cluster-api.sigs.k8s.io/tasks/experimental-features/runtime-sdk/implement-topology-mutation-hook#patch-extension-guidelines
We want patches to be idempotent.
Right now, this burden is the individual patch handlers, namely, the Mutate method defined in the MetaMutator interface).
I think we should implement idempotent patching in a package that all handlers can use, for at least these reasons:
- Idempotence is hard to get right
- Idempotent patching can be implemented in a way that's not specific to any one handler
We want patches to be idempotent.
Right now, this burden is the individual patch handlers, namely, the
Mutatemethod defined in the MetaMutator interface).I think we should implement idempotent patching in a package that all handlers can use, for at least these reasons: