Day 57: Kubernetes Control Plane Troubleshooting Guide | CKA Course 2025
Day 57: Kubernetes Control Plane Troubleshooting Guide | CKA Course 2025
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📚 Welcome to Day 57!
Today we break and fix the control plane—on purpose. You’ll learn how static pods work, why mirror pods appear in kubectl, and how to methodically diagnose failures in the API server, etcd, controller-manager, and scheduler. We’ll use ss (socket stats), journalctl, crictl, and kubectl logs/describe, then repair misflags, bad certs, and path issues. We’ll finish with a clean, exam-style rotation of expired certificates using kubeadm.
🛠 What You’ll Learn in This Demo
✅ Static pods & mirror pods: where manifests live, why control-plane pods “resurrect”
✅ API server triage: ss -lntp, CRI logs, manifest flags, 6443 reachability
✅ etcd troubleshooting: cert/SAN issues, data-dir/volume mistakes, health checks with etcdctl
✅ Controller-manager recovery: kubeconfig/secure-port/signing key fixes; understanding stalled reconciliation
✅ Scheduler recovery: kubeconfig path/typos, leader election, and “Pods Pending” analysis
✅ Certificate rotation the exam way: kubeadm certs renew all + kubeconfig refresh
✅ Practical patterns: read logs first, verify listeners, fix the manifest, let kubelet restart static pods
💡 By the end of this lecture:
You’ll have a repeatable playbook to identify who is broken, why it’s broken, and the minimal fix—exactly the mindset and commands you’ll need for the CKA.
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⏰ Timestamps
00:00:00 Introduction
00:01:07 Prerequisites
00:03:47 Control Plane & Static Pods — Quick Tour
00:15:15 Scenario 1: API Server — diagnose with ss (socket stats) & logs
00:29:47 Scenario 2: etcd — certificate / SAN troubleshooting
00:37:27 Scenario 3: etcd — data dir & volume issues
00:44:02 Scenario 4: Controller Manager — recovery
00:49:28 Scenario 5: Scheduler — unreachable or misconfigured
00:54:47 Scenario 6: Renewing expired certificates (kubeadm)
01:04:20 Outro & Next Steps
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#Kubernetes #CKA #CKA2025 #Troubleshooting #kubeadm #etcd #KubeScheduler #ControllerManager #StaticPods #DevOps #SRE #CloudWithVarJosh #CKACourse