Machine rotation is required against the following scenarios:
Machine Controller will rotate machines automatically when there is a new revision for the MachineDeployment i.e. any change in the .spec.template in the MachineDeployment.
OSM in that case will re-generate the OSC and secrets and annotate them with the revision number using machinedeployment.clusters.k8s.io/revision annotation. Machine Controller waits for the updated secrets and then provisions the machines.
In any other case where a new revision is not rolled out against a change in MachineDeployment. Users will have to manually rotate the machines. To perform this rotation for existing MachineDeployments please follow the guide at Rolling Restart MachineDeploments.
For example, manual rotation is required if user wants to change the OSP for a MachineDeployment.
apiVersion: "cluster.k8s.io/v1alpha1"
kind: MachineDeployment
metadata:
annotations:
k8c.io/operating-system-profile: "osp-ubuntu"
An update to OperatingSystemProfile will not result in an automatic rotation of the machines. This is an intentional design decision since an OperatingSystemProfile can be associated with multiple MachineDeployments. It is the user’s responsibility to rotate the machines when the OperatingSystemProfile is updated. To perform this rotation for existing MachineDeployments please follow the guide at Rolling Restart MachineDeploments.