Short answer
Kubernetes orchestrates containers across a cluster. Pods are the smallest unit and run one or more containers. Deployments manage replica sets for rolling updates, Services give pods stable networking, and ConfigMaps and Secrets inject configuration. The control plane continuously reconciles the actual state of the cluster towards the desired state you declare.
Objects to know
- Pod, ReplicaSet, Deployment, StatefulSet, DaemonSet, Job.
- Service types: ClusterIP, NodePort, LoadBalancer; Ingress for HTTP routing.
- Liveness, readiness and startup probes.
- Requests and limits for CPU and memory; Horizontal Pod Autoscaler.
Declarative model
You describe desired state in YAML. Controllers watch the API server and act to close the gap between desired and actual state, which is what makes self-healing possible.
How to answer it in an interview
- Explain readiness vs liveness probes precisely.
- Walk through what happens during a rolling update.