A company wants to test a new feature in existing software with a small subset of users while the current version stays deployed. If testing succeeds, the company will roll out the new version to all other users simultaneously. Which deployment strategy fits this need?

Canary deployment is the correct strategy because it involves gradually rolling out a new version of an application to a small subset of users first. This allows for testing in a production environment with real traffic, and if successful, the new version can be rolled out to the remaining users. This minimizes risk and allows for quick rollback if issues arise. All-at-once deployment (also known as a "big bang" deployment) releases the new version to all users simultaneously, which is risky. In-place deployment updates the existing instances directly, which can lead to downtime or inconsistencies during the update process. Linear deployment typically refers to a gradual rollout over a set period, which doesn't align with the "simultaneously" rollout to remaining users once testing is complete.