Kubernetes Architecture
6 Topics
1
Why Kubernetes Exists — The Container Orchestration Problem
Moving beyond single-host container management.
Be ready to explain the transition from single-host container management (Docker Compose) to distributed systems. Interviewers look for architectural justification: service discovery across nodes, container rescheduling upon host failure, automated scaling, and rollout strategies.
2
The Control Plane — API Server, etcd, Scheduler, Controller Manager
The brain of a Kubernetes cluster.
This is a key interview area. Expect detailed questions on each component's function, particularly: Why is etcd's quorum mathematical calculation important? How does the scheduler pick node targets? What is the controller manager's reconciliation loop? Remember, the API Server is the only component that directly talks to etcd.
3
Worker Nodes — kubelet, kube-proxy, Container Runtime
Workload executors and networking routing.
Be ready to explain how worker nodes execute instructions. Understand the difference between the Container Runtime Interface (CRI) and Container Network Interface (CNI), how the kubelet reports health status back to the control plane, and how kube-proxy maintains IP tables or IPVS rules for packet routing.
4
kubectl — Your Primary Interface to the Cluster
Sending commands, checking resource status, and troubleshooting.
Practical competency with kubectl is critical. Interviewers may ask you to explain how ~/.kube/config is structured (clusters, users, contexts), and what diagnostic commands you would run to inspect an application crash or print resource JSON paths.
5
Kubernetes Objects and the Declarative Model
Defining target states in YAML vs imperative commands.
Explain the difference between declarative and imperative models. Why is the declarative model preferred in GitOps? Be ready to define the four required root fields in any Kubernetes YAML file: apiVersion, kind, metadata, and spec.
6
How Kubernetes Reconciliation Works — The Control Loop
Continuous convergence toward desired cluster states.
Reconciliation is the fundamental design pattern of Kubernetes. Be prepared to explain the Observe-Compare-Act loop, how self-healing processes (like rescheduling on node failure or CrashLoopBackOff exponential backoffs) resolve discrepancies, and why this model makes Kubernetes exceptionally resilient.