I agree that reproducibility is very important, and it's worth going out of your way get it. On the other hand, it's not entirely clear that you should include

I agree that reproducibility is very important, and it's worth going out of your way get it. On the other hand, it's not entirely clear that you should include all that stuff inside a source control repository. This is something I've grappled with myself, in a number of contexts, and I don't have any great answers. In fact, I've usually just done what you do. Still, given the time and incentives to really do it right, I think a better solution would involve keeping metadata versioned, and storing large binary files extra-repo. Within your repo, you'd have a file or a set of files that indicate that the tools you're using to build/test/deploy/etc are all contained within one or more uniquely identifiable tarballs. Your build process would have a way to extract the contents of those tarballs, if necessary.