Google copybara: moving code between repositories

schrodinger•about 2 hours ago

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?

ASinclair•about 2 hours ago

It’s largely used for syncing external open source projects with the monorepo. Policy is to require source code imports over built artifacts. Though you can get exceptions.

Some projects are also developed in the monorepo and exported via Copybara.

My team also uses it to version Starlark rule sets internally.

paulddraper•43 minutes ago

Source code imports versus artifacts really neither here nor there. Go is source code imports too.

The key part for Copybara is that Google will make changes to the OSS projects from within the internal repo and everyone else will make changes to the OSS projects.

xyzzy_plugh•about 2 hours ago

It's for when you have a monorepo internally, and want to publish parts of it as open source to the world. They still need to live in the monorepo, so this is the solution.

Having a public repo as a dependency for your private corporate repo is a pain in the ass development-wise. Having a tree of such dependencies is a migraine.

xyzzy_plugh•about 2 hours ago

Copybara is one of those things that you should have set up yesterday.

It works great and I've seen many teams gain significant productivity when collaborating in a monorepo with public bits.

If you're even toying with an internal monorepo you owe it to yourself to give it a try.

alok-g•33 minutes ago

Interesting. Anyone knows how this compares to using git submodules and subtrees?

I had used those to create separate repo for website artifacts while the same also remain plugged into the webapp dev repo. (Both sides remain modifiable and changes mergeable to the other side.)

Thx.

jumploops•about 1 hour ago

We’re in the process of open-sourcing a few sub-projects within a monorepo, and didn’t know this existed!

I’m curious what downsides folks have experienced with this tool?

Any tips?

namanyayg•about 3 hours ago

Nice, I built something similar ~5 years ago using nested git repos and scripts to accomplish a similar purpose of combined private and public repos.

My shell script definitely wasn't google scale tho!

UnfitFootprint•about 3 hours ago

Yep, same. I thought it might a wrapper around git subtree but looks like it’s doing quite a lot more!

For example altering commit author emails during sync

MarkSweep•about 2 hours ago

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?

syngrog66•about 1 hour ago

That seems like a tool easily adoptable by folks engaging in dark patterns on GitHub, particularly the malware bait repos.

lysace•about 3 hours ago

Cute name. (Naming is hard and important.)

whh•about 3 hours ago

That tune is in my head again... again...

Google copybara: moving code between repositories

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