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Kubernetes Overview

Kubernetes

Kubernetes (which is also referred to as “K8s” and is described at a high-level on the Kubernetes home page) is an open source system for automating deployment, scaling, and management of containerized applications. You will use the command-line tool, kubectl, extensively when you follow the steps that are described in this runbook. The kubectl download and installation steps are described on kubernetes.io.

Minikube is a variant of Kubernetes that runs a single-node cluster inside a virtual machine (VM) on your laptop. See Minikube for the configuration details for Cúram.

Kubernetes supported version skew

For information to the Kubernetes version and version skew support policy see:
Kubernetes version and version skew support policy.

Some examples are outlined as follows.

kube-apiserver

In highly-available (HA) clusters, the newest and oldest kube-apiserver instances must be within one minor version.

Example:

  • newest kube-apiserver is at 1.31
  • other kube-apiserver instances are supported at 1.31 and 1.30

kubelet

kubelet must not be newer than kube-apiserver, and may be up to two minor versions older.

Example:

  • kube-apiserver is at 1.31
  • kubelet is supported at 1.31, 1.30, and 1.29

Note: If version skew exists between kube-apiserver instances in an HA cluster, this narrows the allowed kubelet versions.

Example:

  • kube-apiserver instances are at 1.31 and 1.30
  • kubelet is supported at 1.30, and 1.29 (1.31 is not supported because that would be newer than the kube-apiserver instance at version 1.30)
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Kubernetes: Minikube