Which deployment pattern involves testing changes on a small subset of users before a full rollout?

• A. Blue-green deployment
• B. Rolling update
• C. Canary deployment
• D. Immutable infrastructure

Answer: (C)

Testing changes on a small subset of users before a full rollout is about a staged rollout that minimizes risk by exposing only a portion of traffic to the new version. This is exactly what a canary deployment does: a new version runs alongside the current one, and a small percentage of users begin using it while the rest see the familiar version. You monitor key metrics and, if everything looks good, gradually shift more traffic to the new version until it fully replaces the old one; if issues arise, you can rollback the canary with limited impact. The other patterns don’t match this approach: blue-green switches all users at once between two environments; rolling updates change instances gradually but typically within the same environment without a defined small-user test group; immutable infrastructure focuses on deploying new resources and retiring old ones rather than testing a subset of users.