CKA Skill Builder: Manually Upgrade a Kubernetes Cluster with kubeadm

In this video, I walk through the manual, command-by-command process of upgrading a Kubernetes cluster across major versions using kubeadm — the exact fundamentals you should understand even if you normally use platforms like Rancher, OpenShift, or Portainer. You’ll see how I upgrade my cluster from Kubernetes 1.32.x → 1.33.x → 1.34.x, including the control plane upgrade first, then upgrading worker nodes safely using cordon/drain, and validating cluster health at each step. What you’ll learn: ✅ Why many teams target N-1 (or even N-2) for stability and supportability ✅ How to prep Ubuntu hosts by updating the Kubernetes APT repo and using package holds ✅ Pre-flight capture: cluster version, node inventory, kube-system pods, and (if applicable) your CNI values ✅ Running kubeadm upgrade plan ✅ Upgrading the first control-plane node with kubeadm upgrade apply ✅ Upgrading additional control-plane nodes with kubeadm upgrade node ✅ Known-good worker workflow High-level flow ✅ Pre-flight snapshots (version/nodes/pods + CNI config) ✅ Update APT repo to the next Kubernetes minor branch and apt-get update ✅ Unhold → upgrade kubeadm → kubeadm upgrade → upgrade kubelet/kubectl → hold ✅ Repeat for remaining control-plane nodes ✅ Cordon/drain workers one at a time, upgrade, restart, uncordon ✅ Validate cluster health, then repeat the same process for the next minor version If you’re studying for CKA, or you want to truly understand what your managed platform is doing “under the covers,” this walkthrough is for you. 💡 Don’t forget to: ✅ Like this video if you find it helpful. ✅ Subscribe to the channel for more home lab, cloud-native tutorials and project showcases. ✅ Drop a comment with your thoughts or questions about the project. Timeline: 0:00 Introduction 1:11 Kubernetes LCM Strategy 5:00 Kubernetes Upgrade Preparation 7:28 Kubernetes Upgrade Pre-Flight Checks 9:08 Kubernetes Upgrade Plan 10:41 1st Controller Node Upgrade 12:37 2nd Controller Node Upgrade 14:55 Reasoning behind manual upgrades 15:34 3rd Controller Node Upgrade 17:02 Worker Node Prep Commands 18:07 Worker Node Upgrade 19:40 Worker Node OS Upgrades 21:42 Summary of ALL Commands 22:46 Worker Node watch command 23:21 Upgrade Complete 23:36 Final Thoughts 👍 If this helped, like, subscribe, and drop a comment with where you’re at in your Kubernetes journey and what you’re upgrading next. ✅ Subscribe to the channel for more Kubernetes and cloud-native tutorials and project showcases. ✅ Drop a comment with your thoughts or questions about the project. #Kubernetes #kubeadm #ClusterUpgrade #KubernetesUpgrade #DevOps #PlatformEngineering #CKA #CNCF #SRE #Linux #Ubuntu #Cilium #KubernetesAdmins