Cloud computing is a new computing paradigm used for building on demand free and open source software (FOSS) applications. However, due to the lack of an explicit and formal description of the resource perspective in the existing FOSS applications, the correctness of Cloud resources management cannot be verified. The main objective of this paper is to propose a formal definition of the resource perspective in FOSS applications as a step towards ensuring a correct and consistent Cloud resource allocation in FOSS application modeling. Hence, we developed a Cloud Resources Allocation Model (CRAM4FOSS) for FOSS applications using the Event-B method. This model is used to formally validate the consistency of Cloud resource allocation for FOSS applications at design time, and to analyze and check its correctness according to the user’s requirements and the resource’s capabilities. The correctness and the consistency of our CRAM4FOSS model have been established into two phases : first, the ProB model-checker is used to detect the most obvious errors and validate the Event-B model by playing some scenarios, then a proof activity is performed to discharge the generated proof obligations that ensure the correctness of the model.