Interview questions in Cloud Platforms, page 4
Migrating a stateful monolith to PaaS
Externalize state to backing services, make processes stateless and disposable, read config from the environment per Twelve-Factor.
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.
Multi-stage Docker builds
A build stage compiles with the toolchain, the final stage uses a minimal base and copies only the artifact, cutting size and attack surface.
Exposing Kubernetes services to the internet
A Service gives stable access and LoadBalancer exposes one service, while Ingress adds L7 host and path routing with TLS for many services.
Running stateful apps with StatefulSets
Stateful apps need stable identity and storage; a StatefulSet gives stable names, ordered rollout, and per-Pod volumes.
Grant an EKS pod IAM access to S3
IRSA maps a service account to an IAM role via the cluster OIDC provider, and pods exchange a projected token for short-lived STS credentials.
Isolate tenants in a shared Kubernetes cluster
Namespaces as the boundary, ResourceQuotas plus LimitRanges to cap compute, default-deny NetworkPolicies for traffic, and RBAC per namespace.
Debug intermittent pod-to-pod connectivity
Scope the failure by path, rule out DNS, inspect kube-proxy iptables and conntrack, check the CNI, then verify cloud security groups and MTU.
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.
State machines versus long-running functions
State machines externalize state, pause for human input without running compute, give built-in retries and audit history, and bill per transition.
Idempotency in event-driven systems
Idempotency means repeated processing yields the same end state; it matters because messages get redelivered; achieve it with idempotency keys and conditional writes.
Distributed tracing for serverless apps
Propagate a trace context through every hop, instrument with OpenTelemetry or X-Ray, capture spans including the database, and correlate traces with structured logs.
Serverless functions with a relational database
Concurrent function instances each open connections and exhaust the database's bounded pool; fix with a connection proxy or pooler, init-phase reuse, or capped concurrency.
High-throughput serverless stream processing
Partition by key for per-user ordering, use a sharded log with batched consumers for backpressure, and tune batch size and shards for cost.
What is Infrastructure as Code?
IaC defines infra in version-controlled files, giving repeatability, peer review, and drift-free consistency, unlike error-prone console clicks.
Automate patching across a VM fleet
Use a patch or config tool to target by tag, roll out in canaried waves with health checks, and prefer immutable golden images long term.
Centralized logging across microservices
Ship structured logs from every service into a central searchable store, then propagate a correlation ID through all hops to trace one request.
State drift in Terraform
Drift is when live infrastructure diverges from recorded state, usually via manual console changes; detect with plan or refresh, remediate by re-applying or importing.
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