What are the steps for upgrading Kubernetes offline via kubeadm. I have a vanilla kubernetes cluster running with no access to internet. In order to upgrade kuberenetes when kubeadm upgrade plan 'command is executed, it reaches out to internet for the plan.
The version of kubernetes used is 22.1.2, CNI used: flannel. Cluster size: 3 master, 5 worker.
It is a time taking process to manage the offline Kubernetes cluster. Because you need to set up your own repositories and registries for images. Once you are done with the setup of the nodes and registries, one can upgrade the cluster based on the requirements. There are a lot of resources available online that will teach how to manage different repositories for each OS distribution.
You can build your own images based on the requirements and push them to the registry. Later these images will help to create the Pods. You need to set up your own CA certificates because container engines require SSL. Example SSL setup.
For more information refer to this K8’s community discussion forum.
