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About Buck2

Buck2 is a build system developed by Meta, specifically engineered to handle the complexities of very large monorepos that incorporate multiple programming languages such as C++, Python, Rust, Kotlin, and Swift. It is a complete rewrite of its predecessor, Buck1, aiming to improve speed, reliability, and extensibility while retaining target compatibility. Buck2 addresses the limitations of traditional build systems like Make when dealing with the scale and diversity of modern large-scale software development. Key aspects of Buck2 include its ability to query build targets, support for remote execution to significantly increase parallelism, and multi-language composability, allowing different language components to interact seamlessly. It integrates with file watching services for efficient change detection and utilizes Starlark, a Python-like language, for defining build targets and advanced manipulations. Written in Rust, Buck2 prioritizes remote execution and features an entirely language-agnostic binary, with all rules defined externally in Starlark, enabling faster iteration and consistent feature availability across all rules.