I know we need to upgrade kubeadm on the control-plane but do we also need to upgrade it to worker node as well?
Yes, you do, to make sure that when you do kubeadm upgrade node that the right code is invoked.
@rob_kodekloud Thank you, when wen run kubeadm upgrade node then which config file on worker node gets updated? it is /var/lib/kubelet/config.yaml ?
Potentially a lot more than that. I’ve never actually checked what gets touched on the node during an upgrade. It’s a good question for Kubernetes slack’s #kubeadm channel
In fact I think it’s not very much that gets done on a worker node.
There are no workloads to upgrade. I believe it is little more than upgrading the kubelet certificates.
The kubelet itself is not upgraded until you apt install kubelet to the new version, and until that is done and the kubelet restarted, the node will not report the new version.
Occasionally kubeadm will inform you of some things that cannot be automatically upgraded and these are often settings for kubelet.