Interview › Kubernetes, Docker, Helm & Podman
Explain the Kubernetes control plane components (API server, etcd, scheduler, controller manager).
Kubernetes, Docker, Helm & Podman · Basic level
Answer
The control plane is the brain of Kubernetes. The API server is the entry point, etcd stores cluster state, the scheduler assigns unscheduled Pods to nodes, and controller managers continuously reconcile actual state back to desired state.
Technical explanation
The API server is the only supported interface for cluster state changes; components watch it and update status or desired state through it.
etcd must be protected with encryption, access control, backups, and quorum-aware operations because it is the source of truth.
Kubernetes resources are declarative API objects; controllers continuously drive actual state toward spec.
The practical interview angle is to connect the concept to reliability: scheduling, healing, scaling, rollout safety, and clear ownership.
Use kubectl get, describe, explain, and -o yaml to move from high-level view to exact spec/status details.
Hands-on example
1. Create a local lab with kind or minikube, then use it to demonstrate: inspect control-plane health using kubectl get pods -n kube-system and kubectl get --raw /readyz?verbose.
2. Run kubectl get nodes -o wide, kubectl get pods -A, kubectl describe, and kubectl get -o yaml to connect the concept to actual cluster state.
3. Make one intentional change, such as a label change, image update, or replica change, and watch how the control plane reconciles it.
4. Capture the command output and convert it into an interview story: desired state, observed state, failure mode, and fix.
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More Kubernetes, Docker, Helm & Podman interview questions
- What is Kubernetes, and what problem does it solve over running containers manually?
- What runs on a worker node (kubelet, kube-proxy, container runtime)?
- What is a Pod, and why does Kubernetes schedule Pods rather than containers?
- What is the difference between a Pod, a ReplicaSet, and a Deployment?
- How does a Deployment perform a rolling update, and how do maxSurge and maxUnavailable work?
- How do you roll back a Deployment, and how does Kubernetes track revisions?
- What is a Service, and what are the types (ClusterIP, NodePort, LoadBalancer, ExternalName)?
- How does a Service select its Pods, and what happens if labels do not match?