Cluster Upgrades

• No other components should have version higher than kube-apiserver.

• Kubectl can have version higher than kube-apiserver.

• IF your cluster is at v1.10.0 and latest version release is v1.13.0 then it would be correct time to upgrade.

• For upgrading we don't directly jump to newer version

• v1.10.0 -> v1.11.0 -> v1.12.0 -> v1.13.0

• Upgrading cluster involves 2 major steps

  • Upgrading Master Node

  • Upgrading Worker Node

• kubeadm Upgrade

  • kubeadm upgrade plan

  • We must manually upgrade kubnelet on each node as kubeadm doesn't do that

• Kubeadm command chain: [Master Node]

  • apt-get upgrade -y kubeadm=1.12:0-00 - new version instead of 1.12

  • kubeadm upgrade apply v1.12.0

  • apt-get upgrade -y kubelet=1.12.0-00

  • systemctl restart kubelet

• Kubeadm command chain: [Worker Node]

  • kubectl drain node1

  • apt-get upgrade -y kubeadm=1.12.0-00

  • apt-get upgrade -y kubelet=1.12.0-00

  • kubeadm upgrade node config --kubelet-version v1.12.0

  • systemctl restart kubelet

  • kubectl uncordon node1

• Kubeadm version is always similar to kubernetes lates.

• Usually update kubeadm first

• Then drain the nodes etc. & proceed forward.