Day 55: Upgrade a Multi-Node Kubernetes Cluster with kubeadm | CKA Course 2025
Day 55: Upgrade a Multi-Node Kubernetes Cluster with kubeadm | CKA Course 2025
👉 GitHub Repository: https://github.com/CloudWithVarJosh/C...
👉 CKA 2025 Playlist: • CKA Certification Course 2025
👉 Kubernetes Projects: • Kubernetes Projects
📚 Welcome to Day 55!
Today we’ll upgrade a production-style, multi-node Kubernetes cluster from v1.32 to v1.33 using kubeadm. We’ll cover versioning and release cadence, safe sequencing, and a practical production upgrade flow. Then we’ll perform a hands-on upgrade: control plane first, update kubelet/kubectl, roll through workers with cordon/drain while respecting PodDisruptionBudgets (PDBs), validate with a NodePort test, and finish with Calico post-upgrade troubleshooting.
🛠 What You’ll Learn in This Demo
✅ When (and when not) to skip versions; understanding release cadence
✅ Production upgrade flow: plan → control plane → kubelet/kubectl → workers
✅ Using kubeadm upgrade plan and dry-run checks with clear rollback points
✅ Cordon/drain in practice and how PDBs affect disruption
✅ Node skew limits and verifying API/server versions post-upgrade
✅ Rolling worker upgrades and health checks you should never skip
✅ Final verification with a NodePort service to confirm data-plane stability
✅ Calico checks: calico-node health, BGP session status, and common post-upgrade fixes
💡 By the end of this lecture:
You’ll be able to run a safe, repeatable cluster upgrade with minimal disruption, confidently validate control-plane and worker health.
🔗 Stay Connected
👉 LinkedIn: / varun-joshi-2b516752
👉 GitHub: https://github.com/CloudWithVarJosh
💬 Got questions? Drop them in the comments — I reply to every single one.
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⏰ Timestamps
00:00:00 Introduction
00:02:02 Prerequisites
00:03:13 Versioning & Release Cadence
00:09:04 Skipping Versions & Sequencing
00:12:37 Why Upgrades Matter + Production Upgrade Flow (Overview)
00:13:23 Production Upgrade Flow (Detailed)
00:17:17 Upgrade Strategies
00:19:12 Demo: Upgrade a Multi-Node Kubernetes Cluster with kubeadm
00:20:01 Demo Prerequisites
00:24:28 Upgrading the Control Plane Node
00:24:55 Step 1: Point APT to the v1.33 repo
00:26:57 Step 2: Determine the target version
00:31:23 Step 3: Plan the upgrade (dry run)
00:36:14 Step 4: Apply the control plane upgrade
00:39:08 Step 5: Verify server version and node skew
00:39:56 Step 6: Upgrade kubelet & kubectl on the control plane
00:42:02 Worker Node Upgrades (One at a Time)
00:42:26 Step 1: Cordon, then drain (from control plane or any admin shell)
00:42:42 Cordon, Drain & PodDisruptionBudget (PDB) Explained
00:53:06 Step 2: Upgrade the worker (on the worker node)
00:54:40 Step 3: Uncordon and verify (from admin shell)
00:56:07 Upgrading worker-2 (repeat)
00:58:54 Final Verification: Expose a Deployment via NodePort
01:01:40 Calico Post-Upgrade Troubleshooting (Important)
01:11:20 Outro & Next Steps
🔖 Hashtags
#Kubernetes #CKA #CKA2025 #kubeadm #Upgrade #VersionSkew #PodDisruptionBudget #Cordon #Drain #Calico #K8sNetworking #DevOps #Containerd #NodePort #K8sCluster #CloudWithVarJosh #CKACourse #SRE #BGP #Troubleshooting