AWS Certified Solutions Architect Professional SAP-C02 Practice Question

The correct answer is to implement a rolling update strategy. A rolling update incrementally replaces instances in the existing Auto Scaling group with new instances running the updated application version. This approach meets all the specified requirements:

• It eliminates downtime by ensuring a minimum number of instances are always in service and passing health checks before old instances are terminated.
• It minimizes the blast radius because if a bug is detected, only the small batch of newly updated instances is affected, and the update can be rolled back.
• It is cost-effective because it reuses the existing infrastructure without needing to provision a full parallel environment.

A blue/green deployment is incorrect because it explicitly requires provisioning a full parallel 'green' environment, which violates the cost constraint of avoiding a duplicate set of infrastructure.

An all-at-once deployment is incorrect because it is the strategy currently in use that causes service interruptions. It updates all instances simultaneously, leading to downtime.

A canary deployment with a separate, smaller fleet is incorrect. While it excels at limiting blast radius, creating a separate fleet (even a small one) still introduces additional infrastructure and complexity not required by a rolling update. The rolling update strategy inherently accomplishes the goal of incremental rollout within the existing infrastructure, making it the most direct and cost-effective solution for this scenario.