A new startup is running a serverless application using AWS Lambda as the primary source of compute. New versions of the application must be made available to a subset of users before deploying…

Blue/green deployments typically involve spinning up a completely new environment and then switching traffic, which, while offering rollback, is less granular for 'subset of users' testing in a phased manner compared to canary deployments for Lambda.

A linear deployment gradually shifts traffic over a defined period, which is a phased rollout but doesn't emphasize the initial small subset testing for early issue detection as effectively as a canary deployment.

A canary deployment strategy allows a new application version to be released to a small, controlled percentage of users first, enabling early detection of issues before a full rollout and providing an immediate rollback mechanism by shifting traffic back to the previous stable version.

An all-at-once deployment immediately exposes all users to the new version, offering no gradual rollout or easy rollback mechanism in case of issues.