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Hands-on Lab·Certified Kubernetes Administrator

Control Plane and Node Components

Every diagram of Kubernetes architecture shows five boxes. On a kubeadm cluster four of them are Pods you can list and one is a systemd unit that is not, and knowing which is which decides where you look when something breaks.

Foundations Guide 3 of 103 Beginner

Component flags below are what kubeadm chose. Another installer picks different ones; the components are the same.

Commands marked with sudo run on the control plane node itself.
Server NameIP AddressOSRolesCPURAMHDD
CKA1001192.168.0.175Ubuntu 26.04 LTSControl Plane Node2 Core4 GB50 GB
CKA1001-NODE01192.168.0.176Ubuntu 26.04 LTSWorker Node2 Core4 GB50 GB
CKA1001-NODE02192.168.0.177Ubuntu 26.04 LTSWorker Node2 Core4 GB50 GB
CKA1001-NODE03192.168.0.178Ubuntu 26.04 LTSWorker Node2 Core4 GB50 GB

This guide includes

Use this when a control plane component is failing and you need to know where it actually lives. This matters because on a kubeadm cluster the control plane is four YAML files on disk, running as Pods that no controller manages.

Before you start

  1. Four files on disk are the entire control plane

  2. Where each component actually runs

  3. The proof those Pods are not ordinary Pods

  4. The kubelet is the exception, and that is the important part

  5. The runtime below the kubelet

  6. Read the components' own arguments

  7. Ask the API server whether it is healthy, and how

  8. etcd, the one component holding state

  9. See the scheduler's decisions in the event log

Official sources

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