DevOps & Cloud Interview Questions and Answers

Stages:

1. Trigger on push or pull request.
2. Build: compile, install dependencies, produce an immutable artefact (container image) tagged with the commit SHA.
3. Static checks: lint, type check, format, secret scanning, and dependency vulnerability scanning.
4. Test: unit, integration and end-to-end tests; fail fast and run slower suites in parallel.
5. Publish artefacts to a registry with the version tag.
6. Deploy to staging automatically, then to production using an approval gate or progressive rollout.
7. Verify with smoke tests, health checks, and automated rollback on failure.

Principles: build once and promote the same artefact, keep pipelines fast and reproducible, treat infrastructure and pipeline definitions as code, and make rollbacks easy. Mention blue/green and canary deployments, plus feature flags to decouple deploy from release.

IaC defines infrastructure (networks, servers, databases, DNS, IAM) in version-controlled declarative files, applied by a tool such as Terraform, Pulumi, CloudFormation or Ansible.

Benefits:

• Reproducibility: environments are created identically from the same code.
• Reviewability: changes go through pull requests with diffs and approvals.
• Auditability: version history shows who changed what and when.
• Disaster recovery: rebuild infrastructure on demand.

Key practices: state management and locking (Terraform remote state), module reuse, environment separation through variables/workspaces, drift detection, and policies (OPA/Sentinel) to enforce guardrails. Immutable infrastructure plus IaC fits container-based platforms especially well.

Observability is the ability to understand a system's internal state from its outputs, so you can debug novel problems without shipping new code.

• Metrics: cheap numeric time series (latency, error rate, saturation, throughput). Great for dashboards and alerting; use histograms/percentiles, not just averages.
• Logs: discrete timestamped events, ideal for detail and forensics. Use structured JSON logs, correlation IDs and appropriate retention/cost control.
• Traces: end-to-end request paths across services showing where time is spent (OpenTelemetry, Jaeger). Essential for microservices and N+1 detection.

Tie it together with SLIs/SLOs and error budgets. Alert on symptoms users feel (high latency, error budget burn) rather than every noisy cause, and drive incident response with runbooks and postmortems.