Upgrading Kubernetes Master Components
When you are running Kubernetes in any capacity that is important for your organization, you will be running the platform in an HA configuration. To achieve that, the typical configuration is at least three replicas of master components, running on three different nodes. This allows you to upgrade single nodes from one minor version to the next, one by one, while still maintaining API compatibility when an upgraded node rejoins the cluster because Kubernetes provides compatibility across one minor version. This means the master components can be on different versions when you are upgrading each node at a time. The following table provides a logical flow of the versions. Let's assume you are upgrading from version 1.14 to 1.15:
Figure 18.14: Upgrade plan for three master nodes
In the following exercise, we will proceed with upgrading the Kubernetes master components.
