The process to upgrade the cluster depends on what we want to do.
If we'd like to upgrade it to a specific Kubernetes version, we can execute a similar process like the one we used to add a new worker node.
kops edit cluster $NAME
Just as before, we are about to edit the cluster definition. The only difference is that this time we're not editing a specific instance group, but the cluster as a whole.
If you explore the YAML file in front of you, you'll see that it contains the information we specified when we created the cluster, combined with the kops default values that we omitted to set.
For now, we're interested in kubernetesVersion. Please find it and change the version from v1.8.4 to v1.8.5. Save and exit.
Now that we modified the desired state of the cluster, we can proceed with kops update.
kops update cluster $NAME ...
