Easy interview questions in DevOps & Cloud, page 4
Why not store uploads on local PaaS disk?
PaaS instances are ephemeral and unshared, so local files vanish on restart and are invisible to peers; store uploads in object storage.
Why Kubernetes Services exist
Pod IPs are ephemeral and change on reschedule; a Service gives a stable virtual IP and DNS name plus load balancing across healthy Pods via label selectors.
How do you manage environment-specific connection strings and why is hardcoding bad?
Tests config separation and secrets hygiene. Outline: inject via environment variables or a secret store, keep per-environment configs credential-free, and prefer managed identities.
Triaging a 5xx error spike
Confirm impact and scope, declare and assign roles, check recent changes, stop the bleeding before root cause.
Deploying to Heroku via Git
Push to the remote, a buildpack detects the language, builds a slug, and runs the Procfile process.
ClusterIP vs NodePort vs LoadBalancer
ClusterIP for internal-only access; NodePort opens a port on every node for basic external reach; LoadBalancer provisions a cloud load balancer for production external traffic.
Why avoid committing secrets to Git, and secure local alternatives?
This tests basic secret hygiene and environment isolation. A strong answer notes Git history is immutable and distributed, so secrets persist in forks forever, and proposes environment variables or gitignored dotenv files.
Primary goal and sections of a post-mortem
Goal is organizational learning and prevention, not blame; include summary, timeline, impact, root cause, action items.
What is Twelve-Factor's config recommendation for CI/CD and scalability?
Tests Factor III and CI/CD scaling implications. Strong answer: config lives in env vars, never in code, so one build promotes across stages and new instances start with correct context immediately. Red flag: config files checked into version control.
Writing a Dockerfile for a web app
FROM a base, set WORKDIR, install dependencies before app code for cache reuse, EXPOSE the port, CMD the start command.
Kubernetes Deployment versus Pod
A Pod is the smallest disposable unit, a Deployment maintains a desired replica count, self-heals, and rolls out updates.
Walk me through a production-ready Dockerfile for a web app
Tests multi-stage builds, layer caching, and security hardening. A strong answer covers a pinned slim FROM, multi-stage separation of build and runtime, ordered COPY for cache, and a non-root USER.
Essential sections of a post-mortem
Summary, impact, timeline, root cause, lessons, and owned action items, each with a clear purpose.
ConfigMap vs Secret
ConfigMaps hold non-sensitive plain config; Secrets hold sensitive data, base64-encoded and treated specially (RBAC, optional encryption at rest).
What is the difference between a Service and an Ingress?
This tests L4 versus L7 networking abstractions. A good answer says Services load-balance to Pods internally while Ingresses route external HTTP to Services via a controller, then gives a path-based scenario.
The 5 Whys root cause technique
Repeatedly ask why to move from symptom to systemic cause, stop at an actionable systemic fix.
Two ways to consume a ConfigMap in a Pod
Inject keys as environment variables (good for a few simple settings), or mount the ConfigMap as a volume of files (good for config files and live updates).
Why blameless culture matters for reviews
Blame causes people to hide facts, so reviews miss systemic causes; blamelessness surfaces honest detail.
Serverless cold starts and how to mitigate them
A cold start is the latency to provision and initialize a fresh environment; mitigate with provisioned concurrency, smaller packages, and lighter runtimes.
Purpose and setup of a Dead-Letter Queue
A DLQ captures messages that repeatedly fail so they neither block the queue nor get lost; configure a redrive policy with a max receive count and alarm on it.
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