Upgrade-Kubernetes.MD

Node Upgrades

Cordon Node: Mark a node unschedulable kubectl cordon <nodename Drain Nodes: kubectl drain node <nodename> : drain and uncordon

kubernetes version Upgrade

deployable kubenernetes package contains all components at same version

All internal deployed components may not have same version.

allows us to upgrade each component independently.

Kubernetes supports only current and current-2 version

upgrade path

Upgrade possibilities

Upgrade plan 1st upgrade master nodes 2nd upgrade worker nodes:

during update master goes down, but pods keep running and services are available. cluster management is not available. pods, if dead, will not be replaced

Upgrade for on-premise

Upgrade Master

1. kubeadm upgrade plan shows current version and next upgrade target
2. upgrade kubeadm apt upgrade -y kubeadm=1.19.0-00
3. Apply upgrade kubeadm upgrade apply v1.19.0
4. upgrade update kubelet apt upgrade -y kubelet=1.19.0-00 on all nodes.
5. service restart kubelet

Upgrade worker Nodes. for each node:

1. Drain node-1
2. upgrade kubeadm and ubelet
3. kubeadm upgrade node config --kubelet-version v1.19.0
4. service restart kubelet
5. kubectl uncordon node-1