Community & Resources

Collection of real-world Copybara usage, blog posts, and community resources.

Companies Using Copybara

Google (Internal Projects)

Google uses Copybara extensively to sync between their internal monorepo (Piper) and public GitHub repositories:

TensorFlow - ML framework synced from internal repo
gRPC - RPC framework with internal/external sync
Abseil - C++ library synced via Copybara
Protobuf - Protocol buffers with internal development
Android (AOSP) - Components synced between internal and public repos

OpenXLA Project

The OpenXLA project documents their Copybara usage extensively:

Source of truth is Google’s internal repo
PRs are imported internally, tested, then submitted
Copybara applies formatting transformations
PRs are closed (not merged) with equivalent commits applied
TSL dependency is copied into third_party/ to prevent broken commits

MongoDB

MongoDB uses Copybara to sync from internal (10gen/mongo) to public (mongodb/mongo):

Excludes sensitive directories (src/mongo/db/modules/**, src/third_party/private/**)
Scrubs commit messages to remove internal references
Preserves acceptable trailers (Co-authored-by, Signed-off-by)
Replaces internal GitHub links with public equivalents

CUE Language

CUE uses Copybara for Gerrit-GitHub bidirectional sync:

Mirrors changes from Gerrit (cue-review.googlesource.com) to GitHub
Imports GitHub PRs into Gerrit for review
Transforms PR titles/bodies into Gerrit commit format

Hasura

Hasura documented their experience using Copybara for monorepo management:

What worked:

Automated bidirectional shadowing of PRs
Transformed OSS contributions to fit monorepo structure

Challenges encountered:

Missing multi-author attribution support
Tool felt “too coupled with Google’s workflows”
Had to fork Copybara to add missing functionality

Their suggestion: Consider a simpler alternative for basic commit-by-commit transformation needs.

Pigweed/Fuchsia

Pigweed uses Copybara to sync Fuchsia libraries:

Files synced to third_party/fuchsia/repo directory
Copybara applies patches (e.g., replacing __builtin_abort with PW_ASSERT)
Avoids requiring downstream projects to clone the large Fuchsia repo

GitHub Actions Integration

Olivr/copybara-action

The copybara-action provides zero-config GitHub Actions integration:

- uses: olivr/copybara-action@v1
  with:
    ssh_key: ${{ secrets.SSH_KEY }}
    # Defaults work for most monorepo → public repo cases

Features:

Zero-config defaults
Bidirectional sync support
Custom Docker image support
Fully customizable for advanced workflows

Blog Posts & Tutorials

Official Resources

Copybara GitHub Repository - Source code and documentation
Copybara Examples - Official examples
Copybara Reference - Complete API reference

Community Tutorials

Moving code between GIT repositories with Copybara (Kubesimplify) - Step-by-step tutorial covering monorepo to public repo sync
Copybara: A Tool for Transforming and Moving Code (Medium) - Introduction and use cases
Google’s Copybara reshapes large-scale code movement - Enterprise adoption overview

Example Configurations

Real copy.bara.sky files from production:

Project	Link	Use Case
MongoDB	copy.bara.sky	Internal → public with scrubbing
CUE	copy.bara.sky	Gerrit ↔ GitHub bidirectional
WireQuery	copy.bara.sky	Open source sync

Community Support

Mailing List

The Copybara OSS Google Group is the official discussion forum:

Ask questions about configuration
Report issues and get help
Discuss feature requests
Share experiences

GitHub Issues

For bugs and feature requests:

google/copybara Issues

Common discussion topics:

Environment variables in configurations (#125)
GitHub PR to Gerrit workflows (#249)
Bidirectional sync patterns (#140)
Multiple config files (#268)

Lessons from Production

Common Patterns

Scrub sensitive content - Use metadata.scrubber() to remove internal references
Preserve attribution - Use metadata.save_author() and metadata.restore_author()
Handle internal links - Use core.replace() to update URLs
Exclude directories - Use glob excludes for private code

Known Limitations

Based on community experiences:

Google-centric design - Some workflows assume Google’s internal tooling
Learning curve - Starlark syntax requires familiarity
Multi-author PRs - May need custom handling (Hasura’s experience)
Transformation quirks - Diffs may differ due to formatting (OpenXLA’s experience)

Tips from Users

Start simple - Use basic push workflow before adding complexity
Test with dry-run - Always use --dry-run before production
Version pin - Pin to specific Copybara versions in CI
Document internally - Keep notes on your specific workflow

git-filter-repo - For one-time history rewriting
git-subtree - For simpler subtree management
repo tool - Android’s multi-repo management

Contributing

If you’ve written about Copybara or have production experience to share:

Open a PR to add your resource
Share on the mailing list
Create a GitHub issue with your use case