Google copybara: moving code between repositories

Ha! This post comes right at the time where I finally got around to open sourcing the patches I made to provide Perforce support which I use at my gamedev studio[0]. I find it kind of funny that perforce support was not included, only git support seems to exist in any meaningful way: despite the primary use of copybara being for releasing internal google code (which lives in Piper, a fork of Perforce). I actually got a bit worried when looking at the git history before making the PR, because there's a lot of Gerrit Change-ID markers (meaning there's some gerrit code review system somewhere which I'm not privvy too) and I might have submitted a PR which never gets upstreamed.. I feel the same pang of pain from the lack of a perforce version of Gerrit/Rietveld.. but, you can't ask for everything! [0]: https://github.com/google/copybara/pull/347

Been using this for a while, mostly when I make a tool as part of a larger project and the tool is big enough to deserve its own release. It’s powerful enough to do a whole bidirectional shipping operation where you export and import code—no thanks, that’s a hassle. I use it mostly for a simple fire and forget export, where I take a folder out of its original repo and preserve the history. Then I just move development to the new repo. The new project layout can be completely different, but Git blame works and I’m happy with that.

To those who have used it: is it handy for situations where you have multiple repos that want to share a little code, but it's not worth the trouble of extracting a library, referencing it, publishing versioned releases, updating dependent repos, etc? And instead just "sync" a code folder from one main repo (perhaps containing common domain models) to other repos? Basically the Go philosophy that a little bit of copying is better than a lot of dependency?

Some other interesting tools in the space. Rust is using a tool called Josh to sync commits: https://josh-project.dev The blog post from the Rust people: https://blog.rust-lang.org/inside-rust/2026/06/04/how-josh-h... Meta used to have an open source tool called fbshipit. But according to its open source repo they no longer use it: https://github.com/facebookarchive/fbshipit Any others in this space?

52+ years of progress... :-) July, 2026: Google copybara allows one to move code between two prod repositories March, 1974: IBM COPY allows one to move code between two prod partitioned data sets: OS/MVT and 0S/VS2 TSO Data Utilities COPY, FORMAT, LIST, MERGE User's Guide and Reference https://www.computinghistory.org.uk/downloads/8987