panchalhimself

Upgrade kubernetes cluster

15 June 2023

So what are we going to do ?

We will upgrade kubernetes cluster from v1.26.0 to v1.27.0.

essentially the upgrade involves installation of kubeadm, kubectl and kubelet packages.

Process of the cluster upgrade from v1.26.0 to v1.27.0 :-

Following are the phases involved during this version upgrade :-

1. upgrade the control node.
2. upgrade the worker nodes.

We will setup the 4 node k8s cluster locally you can checkout k8s-1.3-initialize-and-setup-k8s-cluster.md post on how to set it up.

steps to upgrade control node:-

1. drain the control node using

   kubectl drain CONTROL_NODE --skip-daemonsets

2. install kubeadm package with the v1.27.0 on the control node.

   sudo apt-get install kubeadm=1.27.0-00

3. upgrade the node components using on the control node.

   kubeadm upgrade apply v1.27.0

4. install the kubelet and kubectl v1.27.0 packages on the control node.

   sudo apt-get install kubelet=1.27.0-00 kubectl=1.27.0-00

5. reload system daemon and restart the kubelet on the control node.

    systemctl daemon-reload
    systemctl restart kubelet
   

6. uncordon the control node.

   kubectl uncordon CONTROL_NODE

   

steps to upgrade worker node:-

1. drain the worker node

   kubectl drain WORKER_NODE --skip-daemonsets

2. install kubeadm package with the v1.27.0 on the worker node.

   sudo apt-get install kubeadm=1.27.0-00

3. upgrade the node components using on the worker node.

   kubeadm upgrade node

4. install the kubelet and kubectl v1.27.0 packages on the worker node.

   sudo apt-get install kubelet=1.27.0-00 kubectl=1.27.0-00

5. reload system daemon and restart the kubelet.

    systemctl daemon-reload
    systemctl restart kubelet
   

6. uncordon the worker node.

   kubectl uncordon WORKER_NODE

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