IntermediateTECHNICAL
Explain how you would design a deployment strategy to minimize downtime for a critical web service (include rollback approach, testing, and traffic shifting).
DevOps Engineer
General

Sample Answer

For a critical web service I prefer progressive rollout: build immutable containers, run them in Kubernetes with a service mesh (Istio) for traffic control, and use canary releases with automated health checks. Deploy new pods to a canary subset (5–10%), run synthetic and real-user canary tests for 10–15 minutes, then ramp to 50% and finally 100%. Rollback is automated: if latency or error-rate SLOs worsen by >2x or health checks fail, traffic shifts back instantly via mesh routing and the new pods are torn down. I also run pre-deploy integration and DB migration dry-runs in staging and use feature flags for non-backward-compatible changes. This approach kept a recent e-commerce service at 99.995% availability and reduced rollback time to under 3 minutes.

Keywords

Progressive canary rollouts with Istio/service mesh traffic controlAutomated health and SLO-based rollback triggersPre-deploy testing and feature flags to decouple releases from launches
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