Introduction
If you’re just getting started with Kubernetes, its architecture can feel a bit overwhelming. Let’s break it down into understandable pieces. Kubernetes is like a well-organized team — and each component has a specific role.
Control Plane vs Node Components
Kubernetes is divided into two major layers:
- Control Plane – the brain of the cluster, makes decisions.
- Node Components – the workers, run the actual workloads.
🧠 Control Plane Components
1. API Server (kube-apiserver)
The API server is the front door to your cluster. Everything — kubectl, dashboards, even internal components — talks to the cluster via this API.
kubectl get pods
This command hits the API server first.
2. Scheduler (kube-scheduler)
The scheduler decides where to run a new pod based on resource needs, affinity, taints, etc.
Think of it like a smart dispatcher: “This node has enough RAM, let’s use it!”
3. Controller Manager (kube-controller-manager)
Handles background tasks like scaling, replication, and managing failures.
- Ensures desired state matches current state
- Runs things like ReplicaSet controller, Node controller, etc.
4. etcd
This is the database of Kubernetes. It stores all the cluster state in a consistent and distributed way.
If your etcd dies and there’s no backup — your cluster is toast.
⚙️ Node Components
1. Kubelet
Agent that runs on every node. It receives instructions from the API server and ensures that containers are running as expected.
kubectl describe node
Shows what kubelet is managing.
2. Kube Proxy
Handles networking. It manages network rules to allow communication between services and pods.
3. Container Runtime
It’s what actually runs the containers. Could be Docker, containerd, CRI-O, etc.
Summary Table
| Component | Role |
|---|---|
| API Server | Cluster gateway |
| Scheduler | Pod placement |
| Controller Manager | Keeps things in sync |
| etcd | Stores cluster state |
| Kubelet | Talks to container runtime |
| Kube Proxy | Handles networking |
| Container Runtime | Runs your containers |
Conclusion
You don’t need to memorize everything right away. Just knowing what each component does gives you a solid foundation to understand how Kubernetes works under the hood. Keep exploring — it only gets more interesting from here!
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