Sometime last week we enabled a new API on hg.mozilla.org: json-mozbuildinfo. This endpoint will return JSON describing moz.build-derived metadata about the files that changed in a commit.

Example. Docs.

We plan to eventually leverage this API to do cool things like have MozReview automatically file bugs in the appropriate component and assign appropriate reviewers given the set of changed files in a commit.

The API is currently only available on mozilla-central. And, we have very conservative resource limits in place. So large commits may cause it to error out. As such, the API is considered experimental. Also, performance is not as optimal as it could be. You have to start somewhere.

I'd like to thank Guillaume Destuynder (kang) for his help with the security side of things. When I started on this project, I didn't think I'd be writing C code for spawning secure processes, but here we are. In the not so distant future, I'll likely be adding seccomp(2) into the mix, which will make the execution environment as or more secure than the Firefox content process sandbox, depending on how it is implemented. The rabbit holes we find ourselves in to implement proper security...