Upgrading a Kubernetes v1.28 Cluster using kubeadm
In this article, we will look how we can upgrade a three node Kubernetes v1.28 cluster using kubeadm
Table of contents
Prerequisites
We need a working Kubernetes cluster created using kubeadm
If you haven’t created the cluster, please check my previous article below
This will guide you to create a Kubernetes v1.28.0 cluster
Building a Kubernetes v1.28 Cluster using kubeadm
Upgrade Process
Control Plane
Verify the version of our cluster
# control-plane
kubectl get nodes
NAME STATUS ROLES AGE VERSION
control-plane Ready control-plane 3m6s v1.28.0
node-1 Ready <none> 43s v1.28.0
node-2 Ready <none> 37s v1.28.0
Update the package index and find the latest kubeadm patch available in the repository
# control-plane
sudo apt update
sudo apt-cache madison kubeadm
Unhold the kubeadm package for upgrading
# control-plane
sudo apt-mark unhold kubeadm
Upgrade the kubeadm package to version v1.28.1 and hold the package from automatic upgrading
# control-plane
sudo apt install -y kubeadm=1.28.1-1.1
sudo apt-mark hold kubeadm
Check the upgraded kubeadm version and verify the upgrade plan
# control-plane
sudo kubeadm version
sudo kubeadm upgrade plan
Once our plan is verified, we can upgrade the control-plane by executing the below command
# control-plane
sudo kubeadm upgrade apply v1.28.1
Prepare the control-plane for maintenance by marking it unschedulable and evicting the workloads
# control-plane
kubectl drain control-plane --ignore-daemonsets
Unhold the kubelet and kubectl packages for an upgrade
# control-plane
sudo apt-mark unhold kubelet kubectl
Upgrade kubelet and kubectl packages to version v1.28.1 and hold the packages from automatic upgrading
# control-plane
sudo apt install kubelet=1.28.1-1.1 kubectl=1.28.1-1.1
sudo apt-mark hold kubelet kubectl
Restart the kubelet service on control-plane
# control-plane
sudo systemctl daemon-reload
sudo systemctl restart kubelet
Uncordon the control-plane for marking it as schedulable
# control-plane
kubectl uncordon control-plane
Verify the nodes, now we can see control-plane is upgraded to v1.28.1
# control-plane
kubectl get nodes
NAME STATUS ROLES AGE VERSION
control-plane Ready control-plane 9m17s v1.28.1
node-1 Ready <none> 6m54s v1.28.0
node-2 Ready <none> 6m48s v1.28.0
Nodes
Update the package index on node-1 and node-2 and unhold the kubeadm package for upgrading
# node-1 and node-2
sudo apt update
sudo apt-mark unhold kubeadm
Upgrade the kubeadm package to version v1.28.1 on node-1 and node-2 and hold the package from automatic upgrading
# node-1 and node-2
sudo apt install kubeadm=1.28.1-1.1
sudo apt-mark hold kubeadm
Upgrade the cluster configuration on node-1 and node-2 using the below command
# node-1 and node-2
sudo kubeadm upgrade node
Prepare node-1 and node-2 for maintenance by marking them as unschedulable and evicting the workloads
Execute the below drain command on control-plane
# control-plane
kubectl drain node-1 --ignore-daemonsets --force
kubectl drain node-2 --ignore-daemonsets --force
Unhold the kubelet and kubectl packages for an upgrade
# node-1 and node-2
sudo apt-mark unhold kubelet kubectl
Upgrade kubelet and kubectl packages to version v1.28.1 and hold the packages from automatic upgrading
# node-1 and node-2
sudo apt install kubelet=1.28.1-1.1 kubectl=1.28.1-1.1
sudo apt-mark hold kubelet kubectl
Restart the kubelet service on node-1 and node-2
# node-1 and node-2
sudo systemctl daemon-reload
sudo systemctl restart kubelet
Uncordon node-1 and node-2 for marking it as schedulable
Execute the below uncordon command on the control-plane
# control-plane
kubectl uncordon node-1
kubectl uncordon node-2
Now our cluster is fully upgraded to v1.28.1
Verify the same by executing the below command on the control-plane
# control-plane
kubectl get nodes
NAME STATUS ROLES AGE VERSION
control-plane Ready control-plane 14m v1.28.1
node-1 Ready <none> 11m v1.28.1
node-2 Ready <none> 11m v1.28.1
Reference
https://kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/