CKA Certification Course 2025 - 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/CKA-Certification-Course-2025 👉 CKA 2025 Playlist: https://youtube.com/playlist?list=PLmPit9IIdzwRjqD-l_sZBDdPlcSfKqpAt&si=1JNRkoNa75AOJx0o 👉 Kubernetes Projects: https://www.youtube.com/playlist?list=PLmPit9IIdzwSv2zwizysG6OwWUACpQFN0 📚 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: https://linkedin.com/in/varun-joshi-2b516752 👉 GitHub: https://github.com/CloudWithVarJosh 💬 Got questions? Drop them in the comments — I reply to every single one. 👍 Like, share, and subscribe to follow the entire CKA 2025 series! ⏰ 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