The Vesta Software Configuration Management System

Vesta is a system for software configuration management. It stores collections of source files, keeps track of which versions of which files go together, and automates the process of building a complete software artifact from its component pieces. Unlike other software configuration management systems, Vesta was specifically designed to handle very large projects—tens of millions of lines of code and beyond. Vesta’s novel approach gives it three important properties not available in other systems. First, every build is repeatable, because its component sources and build tools are stored immutably and immortally, and its configuration description completely describes what components and tools are used and how they are put together. Second, every build is incremental, because results of previous builds are cached and reused. Third, every build is consistent, because all build dependencies are automatically captured, recorded, and checked, so that a cached result from a previous build is reused only when doing so is certain to be correct. In addition, Vesta’s flexible language for writing configuration descriptions makes it easy to describe large software configurations in a modular fashion and to create variant configurations by customizing build parameters. This report describes the Vesta technology in detail and discusses the performance of our implementation.