The Upgrade Process
In this section, you will see the steps required to upgrade the Kubernetes platform. Note that upgrading the underlying OS is not covered here. To meet the requirement of zero-downtime upgrades, you must have an HA Kubernetes cluster with a minimum of three masters and etcd servers, which enables frictionless upgrades. The process will take one node out of the three and upgrade it. The upgraded component then will rejoin the cluster, and then we take the second node and apply the upgrade process to it. Since, at any given time, at least two of the servers are kept available, the cluster will remain available during the upgrade.
Some Considerations for kops
We have guided you through the creation of an HA Kubernetes cluster in Chapter 11, Build Your Own HA Cluster. Hence, in this chapter, we will walk you through upgrading the same cluster.
As mentioned in that chapter, there are various ways of deploying and managing a Kubernetes cluster. We have opted...