Trigger rolling update of machines without changing machine class reference

[rfranzke]

What would you like to be added: It would be nice to have a trigger for a rollout of the machines without the necessity to change the machine class reference.

Why is this needed: Apply updates/changes that are only done when the machine is created/booted the first time.

/cc @guydaichs

[hardikdr]

Interesting. Btw this can be achieved if the same MachineClass is updated with new values. The values will be in effect only when the new machine is created or old one is deleted.

[zuzzas]

We're doing it by changing the .spec.template.metadata.annotations. Basically, adding or changing any annotation there will trigger the rollout of new Machines.

I encourage you to use this pattern instead of developing a new feature. It's widely known and used when triggering Kubernetes' Deployment's rolling update.

[himanshu-kun]

/close as there are other ways of triggering rolling update as mentioned in the above comment https://github.com/gardener/machine-controller-manager/issues/517#issuecomment-700663951