[fipar]

It can also be used if you want part of your monorepo to track something open source from the world.

Say, to rebase upstream MySQL changes onto a fork in the monorepo (in a random, non-specific example)

[yaskou]

Yeah, that's the fun part. Probably built first for exporting monolith slices to OSS, but the reverse direction is more interesting to me. Tracking an upstream or keeping a private fork in sync. That's what makes Copybara useful well beyond the monorepo use case.