upgrade kubernetes version

[HendrikZe]

Hi,

what's the best way to upgrade the kubernetes version of an existing cluster?

Thanks in advance

[Privatecoder]

I would upgrade regular kubeadm-Clusters like this however the K8s version is referenced in multiple places, namely

KubeadmControlPlane
KubeadmConfigTemplate md-0
KubeadmConfigTemplate md-1
MachineDeployment md-0
MachineDeployment md-1

I guess one has to touch those..

[Privatecoder]

I just tried by editing a KubeadmConfigTemplate followed by the corresponding MachineDeployment which triggered the creation of a new HCloud machine, cordoning of an existing node followed by a removal.

The new node was running the new K8s version afterwards, however I am not sure how this would work with baremetal (do we need to re-initialize the bm-node?).

[Privatecoder]

Found this issue here #591 and also this blog article https://blogs.oracle.com/cloud-infrastructure/post/cluster-api-upgrade-kubernetes-cluster-in-oci

[batistein]

In general:

1. New node images (via packer or via pre/postkubeadmCommands)
2. Create new ProviderMachineTemplates & KubeadmConfigTemplates
3. Change the KubeadmControlPlane configuration more information: https://cluster-api.sigs.k8s.io/tasks/upgrading-clusters.html#how-to-upgrade-the-kubernetes-control-plane-version
4. Change the MachineDeployment