Technical interview guide

Deployment Strategies (Blue-Green, Canary, Rolling)

Different ways to roll a new version out safely, trading off speed, blast radius, and infrastructure cost.

Read: 30 min
Practice MCQs: 25
Interview QA: 25
Edition: v4
Editorial status: Reviewed
Relevant for: AI EngineerDevOps EngineerForward Deployed Engineer (FDE)MLOps EngineerPlatform EngineerSite Reliability Engineer

Scope: Kubernetes, Argo Rollouts, Istio, Flagger, Amazon ECS, OpenFeature, DORA, Google SRE, and NIST guidance current 2026-08-31.

Interview QA

Treat each question like a live interview question: answer out loud first (structure, assumptions, tradeoffs), then open the model answer to spot gaps and rehearse a tighter follow-up.

Curated: 2026-10-05 · Written: 2026-10-05 · Reviewed: 2026-10-03

QA-1

Choose a deployment strategy for a critical service.

QA-2

Design a safe rolling update.

QA-3

Design a blue-green deployment.

QA-4

Design an evidence-based canary rollout.

QA-5

Select a representative canary cohort.

QA-6

Design canary promotion guardrails.

QA-7

Handle delayed outcomes in a canary.

QA-8

Validate configured versus achieved traffic split.

QA-9

Use traffic mirroring safely.

QA-10

Plan database changes across a mixed-version rollout.

QA-11

Respond when a canary corrupts data.

QA-12

How do you implement weighted traffic routing and sticky sessions for canary deployments at the load balancer or ingress layer?

QA-13

How do you coordinate automated rollbacks across interdependent microservices during a failed rolling deployment?

QA-14

Design promotion and abort as an idempotent state machine.

QA-15

Handle missing or delayed rollout telemetry.

QA-16

Roll back a release with long-lived connections.

QA-17

Coordinate background jobs during blue-green deployment.

QA-18

Design deployment recovery when rollback is unsafe.

QA-19

How do you design synthetic testing and automated canary analysis (ACA) to gate traffic promotion in phased rollouts?

QA-20

How do you define error budgets, key metrics, and observation windows to detect canary regressions and avoid false promotions?

QA-21

Measure deployment-strategy effectiveness.

QA-22

Migrate from all-at-once releases to progressive delivery.

QA-23

Review a rollout definition before release.

QA-24

Review deployment strategy before production launch.

QA-25