In recent years, Cloud Computing has emerged as one of the most predominant paradigm in the ICT world. For instance, services used every day by millions of people such as Dropbox and Google Drive, social networks as Facebook and Twitter, but also companies, rely on Cloud Computing, since it allows to perform outsourcing, minimizing hence part of the costs due to to buy and maintain expensive computer infrastructure. Cloud Computing, in a nutshell, is a model for rapidly provisioning a set of on demand configurable computing resources such as networks, servers, storage, applications. Some of its main features are the high automation on provisioning of resources, the pooling between several clients and the elastic availability which allows to instantiate many resources in a short time.