Upgrade workflow


I’m looking on how I can update a Kubernetes cluster launched with Rancher.
I’ve done a Rancher update which was pretty simple and well documented.

Now, I’m looking to upgrade the K8s cluster. I’ve read the documentation and is looks easy to do.
However : It seems that, after clicking on Save, the cluster won’t be available.

From the documentation :

  1. From the Global view, find the cluster for which you want to upgrade Kubernetes. Select Vertical Ellipsis (…) > Edit .
  2. Expand Cluster Options .
  3. From the Kubernetes Version drop-down, choose the version of Kubernetes that you want to use for the cluster.
  4. Click Save .
    Result: Kubernetes begins upgrading for the cluster. During the upgrade, your cluster is unavailable.

What is the workflow of an upgrade ? Are all the worker nodes stopped ? Are they stopped and updated one by one ?

Thanks in advance.