Razorpay Containers & Kubernetes interview questions

Selectors match object labels; owner references record controller relationships. Keeping those mechanisms separate explains how a Service can select the wrong pods without owning them.

The loop is easy; the statistics are not. This question finds engineers who can size a traffic slice against sample noise and name the false rollback that kills trust in automation.

Priority is one number with three separate effects: scheduling order, preemption victim selection, and eviction order under node pressure. Conflating those is the trap; designing tiers that survive both a full cluster and a hot node is the pass.

The gating instinct is right and the cardinality is wrong: init containers make every new replica race the same migration. Here is the once-per-release shape, plus the rollback rule that shapes all DDL review.

Exit codes, the previous-container log, and a little-known file at /dev/termination-log that carries a container's last words into kubectl output. Scale triage starts with classification, not with opening pods.

Volumes grow online and never shrink; StatefulSet template changes normally replace pods ordinal by ordinal; supported in-place pod resize is a separate path. The craft is expanding storage first, gating rolls with partition, and letting replication lag set the pace.

Both run pods, so the answer sounds obvious until an interviewer asks what happens when you delete one. The guarantees are narrower and more specific than most candidates think.

The pair everyone configures and few can explain. QoS hints at eviction risk, but usage versus requests and Pod priority determine node-pressure ranking, and CPU and memory behave completely differently when you exceed them.

A pod is a shared network and storage boundary that happens to contain containers. Once you can say what the containers inside one share, sidecars and init containers stop needing separate explanations.

Service types choose how an application is exposed. Follow the actual traffic path: cloud controllers can target nodes or pods, and internal exposure differs from public exposure.

A Service moves connections and an Ingress reads requests. The gap between those two sentences is hostname routing, path routing and TLS, and it is also why an Ingress object alone does nothing.

Follow a Deployment change through the API server, controllers, scheduler and kubelet. Each handoff gives you a different place to investigate when a pod never starts.

The single most common Kubernetes interview question, and the one where a vague answer is most obvious. Every stage you name is a place the interviewer can ask you to debug.

Everyone can recite the three. Explain what each failure causes, and why a badly configured liveness probe is more dangerous than none at all.

Almost always a finalizer, and the fast fix is the one that loses data. The safe answer explains what the finalizer is protecting against before removing it.

Build instructions depend on earlier inputs, so changing source can invalidate a dependency installation placed after it. Ordering the Dockerfile by how often things change is the whole optimisation, and multi-stage is how the compiler stops shipping to production.

The writable layer is part of the container, not the image, and it dies with the container. Everything about volumes follows from knowing which of those two a file is in.

Evaluate identity, traffic policy and telemetry against measured proxy overhead and operating responsibilities, then test the authorization boundary.

Trace sandbox setup, address allocation and a cross-node packet, then distinguish pod reachability from Service translation.

A VM virtualises hardware and boots its own kernel. A container is a process on the host kernel with its view of the world restricted. Everything else, including the security answer, follows from that one difference.

Three states, three completely different causes, and one command that tells you which you are looking at. The state name says whether the problem is the scheduler, the registry or your own process.