Interview › Kubernetes, Docker, Helm & Podman
What runs on a worker node (kubelet, kube-proxy, container runtime)?
Kubernetes, Docker, Helm & Podman · Basic level
Answer
A worker node runs kubelet, a container runtime such as containerd or CRI-O, kube-proxy or an equivalent data-plane implementation, and node-level agents like CNI, CSI, logging, and monitoring components. Kubelet is the main node agent that makes Pods real on that node.
Technical explanation
kubelet does not run containers directly; it talks to the runtime through CRI and reports Pod/node status back to the API server.
Node reliability depends on kubelet health, runtime health, disk pressure, memory pressure, network plugin health, and certificate validity.
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 a worker node with kubectl describe node and check kubelet/runtime conditions.
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?
- Explain the Kubernetes control plane components (API server, etcd, scheduler, controller manager).
- 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?