Virtual Machine Contracts for Datacenter and Cloud Computing Environments

Virtualization is an important enabling technology for many large private datacenters and cloud computing environments. Virtual machines often have complex expectations of their runtime environment such as access to a particular network segment or storage system. Similarly, the runtime environment may have complex expectations of a virtual machine's behavior such as compliance with network access control criteria or limits on the type and quantity of network traffic generated by the virtual machine. Today, these diverse requirements are too often specified, communicated and managed with non-portable, site specific, loosely coupled, and out-of-band processes. We propose Virtual Machine Contracts (VMCs), a platform independent way of automating the communication and management of such requirements. We describe how VMCs can be expressed through additions to the Open Virtual Machine Format (OVF) standard and how they can be managed in a uniform way even across environments with heterogeneous elements for enforcement. We explore use cases for this approach and argue that it is an essential step towards automated control and management of virtual machines in large datacenters and cloud computing environments.