A company is migrating a monolithic e-commerce application to a microservices architecture on AWS. The migration must minimize downtime and allow rollback. Which migration strategy should the company use?
The strangler fig pattern incrementally routes specific functions from the monolith to new microservices behind a facade, so each slice can be released and rolled back independently. This satisfies both the minimal-downtime and rollback constraints, unlike a single big-bang cutover.
Why this answer
The strangler fig pattern incrementally replaces pieces of a monolith with microservices by routing traffic through a facade, allowing new services to be introduced alongside the legacy system. This minimizes downtime because the monolith keeps serving unaffected functionality while migrated components go live, and it enables rollback by simply routing traffic back to the old path. It is the standard AWS-recommended approach for low-risk monolith decomposition.
Exam trap
SAP-C02 often tests whether candidates conflate the general act of refactoring with a specific incremental migration pattern, so pick the option that explicitly describes gradual replacement with rollback capability.
How to eliminate wrong answers
Option A is wrong because refactoring is the broader activity of rewriting code, not a migration strategy that by itself guarantees minimal downtime or rollback — it describes what you do, not how you cut over safely. Option B is wrong because a big bang migration replaces everything at once, maximizing downtime and offering no practical rollback path if the new system fails. Option D is wrong because rehost (lift and shift) moves the monolith to EC2 as-is and does not decompose it into microservices, so it fails the architectural goal.