Résumé: Microservices architecture represents a new way of designing and implementing software systems. This architectural style focuses on the development of small, independent and loosely coupled services that communicate with each other via precisely defined interfaces. Although this architectural style has several advantages, such as flexibility and the ability to integrate multiple technologies, it brings significant challenges, especially in managing variability due to its level of granularity, the number of possible variants and their combinations. The design of complex microservices architectures requires an organised exploration of architectural alternatives while maintaining functional coherence. In this paper, we propose a model-driven approach (MDA) to managing variability through a transformation from the CIM level (use case diagram) to the PIM level (feature diagram), where use cases serve as the primary artefact for architectural variability. Our contribution is based on a formal method for generating all valid configurations for a microservices-based system. The method consists of classifying use cases into two types: Endpoint and Simple Use Case. Configurations are then generated by combining use cases according to their relationships. Our framework is based on a strict combinatorial generation that ensures consistency and full traceability from requirements to resulted architecture. The configurations resulting from the CIM level are visualised as candidate architectures at the PIM level using features diagram.