The Classics Never Go Out of Style An Empirical Study of Downgrades from the Bazel Build Technology

Software build systems specify how source code is transformed into deliverables. Keeping build systems in sync with the software artifacts that they build while retaining their capacity to quickly produce updated deliverables requires a serious investment of de-velopment effort. Enticed by advanced features, several software teams have migrated their build systems to a modern generation of build technologies (e.g., Bazel, Buck), which aim to reduce the maintenance and execution overhead that build systems impose on development. However, not all migrations lead to perceived improvements, ultimately culminating in abandonment of the build technology. While prior work has focused on upward migration towards more advanced technologies, so-called downgrades, i.e., abandonment of a modern build technology in favour of a traditional one, remains largely unexplored. In this paper, we perform an empirical study to better understand the abandonment of Bazel-a modern build technology with native support for multi-language software projects and (local/distributed) artifact caching. Our investigation of 542 projects that adopt Bazel reveals that (1) 61 projects (11.2%) have abandoned Bazel; and (2) abandonment tends to occur after investing in Bazel for a substantial amount of time (a median of 638 days). Thematic analysis reveals seven recurring reasons for abandonment, such as technical challenges, lack of platform integration, team coordi-nation issues, and upstream trends. After abandoning Bazel, the studied projects have adopted a broad set of alternatives, spanning from language-specific tools like Go Build, to more traditional build technologies like CMake and even pure Make. These results demonstrate that choosing a build technology involves balancing tradeoffs that are not always optimized by adopting the latest technology. This paper also lays the foundation for future work on balancing the tradeoffs that are associated with build technology choice (e.g., feature richness vs. maintenance costs) and the development of tools to support migration away from modern technologies.