Managing the virtual machine lifecycle of the CernVM project

CernVM is a virtual software appliance designed to support the development cycle and provide a runtime environment for LHC applications. It consists of a minimal Linux distribution, a specially tuned file system designed to deliver application software on demand, and contextualization tools. The maintenance of these components involves a variety of different procedures and tools that cannot always connect with each other. Additionally, most of these procedures need to be performed frequently. Currently, in the CernVM project, every time we build a new virtual machine image, we have to perform the whole process manually, because of the heterogeneity of the tools involved. The overall process is error-prone and time-consuming. Therefore, to simplify and aid this continuous maintenance process, we are developing a framework that combines these virtually unrelated tools with a single, coherent interface. To do so, we identified all the involved procedures and their tools, tracked their dependencies and organized them into logical groups (e.g. build, test, instantiate). These groups define the procedures that are performed throughout the lifetime of a virtual machine. In this paper we describe the Virtual Machine Lifecycle and the framework we developed (iAgent) in order to simplify the maintenance process.