Buck2: Our open source build system

Do smaller companies (smaller than Meta and Google) use these kinds of build tools much? It seems like a system that rebuilds everything whenever a dependency changes is more suited an environment that has very few, if any, external dependencies.

Is anyone using Buck/Bazel and also using frameworks like Spring, or React, for example?

I used Bazel for a long time, in a small team (5). No spring/react for me, but we have ~100 external dependencies across 5 languages. It was generally positive, certainly better than any system we used beforehand, and multi-language stuff was great, but the learning curve was steep and it had annoying defaults (which we soon wrapped with our own).

Regarding 3rd party packages, if you update them regularly and they are depended on by intensive builds, that’s going to be the reality in any build system worth using. A build is a DAG and if one node changes then it’s children must too, if you want any guarantee that the update isn’t going to break fresh builds. As with any build, if you want fewer rebuilds you need to be diligent with assigning dependencies to things that need them (so unrelated things don’t rebuild), and when things can be divided and conquered then they should be.

Bazel it isn’t perfect at reproducibility and thats what made me abandon ship. It isn’t perfectly sandboxed, for instance - it still uses your system compilers, still has access to your system libraries. This means that you can accidentally depend on something without specifying it, which violates my requirement for true reproducibility.

These days we use Nix, which is ultimately a better environment for developing reproducible builds if you’re happy to shun Windows. It is also a superior language to Starlark IMO - declarative makes much more sense than imperative in something that has to later resolve to a DAG. In terms of using it as a build system, it’s lacking unless you put in the legwork. The default is to use other build systems within Nix, but that leads to a lot of unnecessary rebuilding during development, so we just span up our own Bazel-like library for Nix to do the heavy lifting.