Devops
294 bites tagged Devops — interview questions with model answers, and 60-second explainers.
How do Docker images and containers differ and relate?
This tests your grasp of the immutable template versus mutable runtime boundary. A good answer: an image is a read-only layered template with code and dependencies; a container is a runnable instance with a writable layer on top.
ConfigMap decouples config from container images
A ConfigMap is a key-value store that injects configuration into pods without rebuilding the image. Use it for feature flags, database hostnames, or any non-secret settings. Editing one does not restart existing pods, so stale config is the common footgun.
Design a CI/CD step to auto-lint application content
Rule types (terminology, placeholders, i18n), tools (TextLint, Vale, AST), and failure mode (block vs warn). Operationalizing content quality gates in CI/CD. Treating it as post-deploy check or spell-check.
GitLab Flex merges seats and AI into one budget
GitLab Flex reshapes one annual budget monthly across seats, AI credits, and features without re-procurement. Engineering leaders can shift spend from idle seats to agent usage instead of guessing headcount six months out. Ask at renewal.
GitLab Orbit unifies code lifecycle in live graph
GitLab Orbit beta unifies code, pipelines, and ownership in a live graph. Compare the Market tests show Orbit-grounded reviewers hit 70% accuracy versus 58% for RAG.
Design a golden path CI/CD pipeline for a Go API
Propose build, test, SAST, containerize, deploy stages with hooks or config overlays for flexibility. Balancing standardization with team autonomy. A rigid pipeline with no escape hatches or weak security gates.
How would you create and distribute reusable IaC components at scale?
This tests platform engineering governance at scale. A strong answer proposes a versioned module registry, policy-as-code guardrails, automated validation pipelines, and self-service documentation.
What is an artifact repository and why not just a shared filesystem?
Tests your grasp of immutability, metadata, and access control for build artifacts. A strong answer covers versioning, checksums, RBAC, and API retrieval that NFS lacks. Red flag: saying a shared filesystem is simpler and therefore enough for production.
What is Git LFS and what are its CI/CD trade-offs?
This tests whether you understand Git's object model limits. A strong answer covers pointer indirection, smudge filters, and the shift of download burden to the LFS server in CI. A red flag is claiming LFS eliminates large file transfers entirely.
How do you add a basic post-deployment health check in CI/CD?
Tests deployment validation beyond exit-code success. Outline: add a post-deploy stage that probes an HTTP endpoint, checks status code and latency, validates critical dependencies, and triggers rollback on failure.
How do you keep one build artifact immutable across environments?
This tests separation of build and run stages. A strong answer packages one artifact with zero embedded config, then injects env vars or mounted secrets at deploy time via the platform. Red flags include per-stage rebuilds or config baked into the image.
How would you design an automated artifact repository cleanup policy?
Balancing cost, compliance, and speed via tiered artifact retention. A strong answer covers age rules, deployment state, protected tags, and dry-run gates.
Compare monorepo and polyrepo strategies in CI/CD
Tests repo structure impact on builds, dependencies, and pipeline triggers. Contrast monorepo atomicity with polyrepo autonomy; cover monorepo change-detection versus polyrepo versioning and contract tests.
Design a dynamic, risk-based quality gate system
Tests if you can move CI/CD from binary pass/fail to contextual risk scoring. Strong answers define criticality tiers, weight signals by severity and blast radius, and emit GO/CAUTION/STOP states.
Design a Docker artifact system for cost, traceability, and speed
Tests cost-speed-auditability tradeoffs for artifacts at scale. Strong answers cover tiered storage with lifecycle policies,immutable build provenance,regional caching, and automated garbage collection. Red flag: infinite mutable storage with no cleanup rules.
Diagnose CI/CD queue bottlenecks and propose three throughput improvements
This tests CI/CD scheduling and queuing theory. A strong answer profiles queue versus execution time, then proposes right-sizing parallelism, aggressive caching, and workload sharding. A red flag is jumping straight to adding agents without measuring first.
How do you manage secrets for hundreds of services in centralized CI/CD?
It tests secret sprawl prevention and least privilege in CI/CD. Answer: use a secrets manager with RBAC, short-lived credentials, runtime injection, and audit logs. Red flag: secrets in Git, plain env vars, or one shared master key.
How do you version shared CI steps and handle breaking changes?
This tests CI hygiene and consumer safety. Pin shared steps to immutable tags or SHAs, use semantic versioning, and force consumers to opt into breaking changes. Red flag: referencing a mutable branch like main for reusable workflows.
Describe high-level steps to onboard a microservice via self-service CI/CD
Tests platform thinking and developer experience design. A strong answer outlines a golden path: templated repo setup, standardized build/test stages, environment promotion, and observability hooks, plus guardrails not blockers.
How would you instrument CI/CD to measure a DORA metric accurately?
Tests mapping DORA definitions to pipeline events. A strong answer picks one metric, defines exact boundaries from merge to production, and correlates deployments with incidents.
How do you diagnose a progressively slower CI pipeline?
Profile stage durations and critical path, audit runner CPU/memory/disk, flag flaky or late-failing tests. data-driven CI diagnosis across pipeline topology, runner resources, and test quality.
How would you use a Kubernetes Admission Controller as CI/CD security gate?
Tests pre-deployment enforcement via admission webhooks. Strong answers: ValidatingAdmissionWebhooks blocking bad manifests, Pod Security Standards restricted profiles, and OPA/Gatekeeper for image signatures. Red flag: confusing with RBAC or runtime scanning.
Rolling vs blue/green deployments: differences and trade-offs
Tests risk-cost-downtime judgment. Contrast rolling's gradual swap with blue/green's parallel swap; rolling is cheaper but mixes versions, while blue/green doubles capacity for instant rollback. Red flag: saying blue/green cheaper or rolling double-capacity
Compare GitOps and Kustomize vs Ansible for environment configs
Tests declarative vs imperative trade-offs. Contrast GitOps drift detection with Ansible's imperative flexibility. Note Kustomize overlays for K8s vs Ansible's broader reach.
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