Git Destinations

Git Destinations

Git destinations define where Copybara writes transformed code.

git.destination

Direct push to a Git repository:

destination = git.destination(
    url = "https://github.com/org/repo.git",
    fetch = "main",
    push = "main",
)

Parameters

Parameter	Required	Description
url	Yes	Repository URL (HTTPS or SSH)
push	Yes	Branch to push to
fetch	No	Branch to fetch (default: same as push)
tag_name	No	Create a tag with this name
tag_msg	No	Tag message
skip_push	No	Skip the push (for testing)

Examples

# Basic push to main
destination = git.destination(
    url = "https://github.com/org/repo",
    push = "main",
)

# Push to different branch
destination = git.destination(
    url = "https://github.com/org/repo",
    fetch = "main",
    push = "sync/latest",
)

# Create a tag
destination = git.destination(
    url = "https://github.com/org/repo",
    push = "main",
    tag_name = "v${VERSION}",
    tag_msg = "Release ${VERSION}",
)

# SSH URL
destination = git.destination(
    url = "git@github.com:org/repo.git",
    push = "main",
)

git.github_destination

GitHub-specific destination with API integration:

destination = git.github_destination(
    url = "https://github.com/org/repo",
    push = "main",
)

Additional Features

• Automatic CODEOWNERS validation
• GitHub API integration for metadata
• Better error messages for GitHub-specific issues

destination = git.github_destination(
    url = "https://github.com/org/repo",
    push = "main",
    skip_push = False,
)

git.github_pr_destination

Create pull requests instead of pushing directly:

destination = git.github_pr_destination(
    url = "https://github.com/org/repo",
    destination_ref = "main",
    pr_branch = "copybara/sync-${CONTEXT_REFERENCE}",
)

Parameters

Parameter	Required	Description
url	Yes	Repository URL
destination_ref	Yes	Target branch for the PR
pr_branch	No	Branch name for the PR
title	No	PR title
body	No	PR description
draft	No	Create as draft PR
update_description	No	Update PR description on re-run
assignees	No	List of assignees
labels	No	List of labels

Examples

# Basic PR
destination = git.github_pr_destination(
    url = "https://github.com/org/repo",
    destination_ref = "main",
)

# Full configuration
destination = git.github_pr_destination(
    url = "https://github.com/org/repo",
    destination_ref = "main",
    pr_branch = "copybara/sync-${CONTEXT_REFERENCE}",
    title = "Sync from internal",
    body = """\
Automated sync from internal repository.

Please review and merge.
""",
    draft = False,
    update_description = True,
    assignees = ["reviewer1"],
    labels = ["automated", "sync"],
)

Tip

Use ${CONTEXT_REFERENCE} in pr_branch to create unique branch names based on the source commit.

git.gerrit_destination

Create Gerrit change lists:

destination = git.gerrit_destination(
    url = "https://gerrit.example.com/repo",
    fetch = "main",
    push_to_refs_for = "main",
)

Parameters

Parameter	Description
url	Gerrit repository URL
fetch	Branch to fetch
push_to_refs_for	Target branch for the CL
submit	Auto-submit after creating
notify	Notification setting

destination = git.gerrit_destination(
    url = "https://gerrit.example.com/repo",
    fetch = "main",
    push_to_refs_for = "main",
    notify = "OWNER",  # Notify owner only
)

Fetch vs Push

The fetch and push parameters serve different purposes:

• fetch: The branch to read current state from (for merging)
• push: The branch to push changes to

# Same branch (common)
destination = git.destination(
    url = "...",
    push = "main",
)  # fetch defaults to push

# Different branches
destination = git.destination(
    url = "...",
    fetch = "main",      # Read from main
    push = "sync/main",  # Push to sync/main
)

Skipping Push

For testing without actually pushing:

destination = git.destination(
    url = "...",
    push = "main",
    skip_push = True,  # Don't actually push
)

Note

Use skip_push = True during development to see what would be pushed without modifying the destination.

Force Push Behavior

Copybara handles push conflicts:

1. Normal push: Fast-forward only
2. With --force: Force push (destructive!)

# Normal (safe)
java -jar copybara.jar migrate copy.bara.sky

# Force (destructive)
java -jar copybara.jar migrate copy.bara.sky --force

Caution

Use --force carefully - it will overwrite destination history.

Authentication

Destinations require write access:

# HTTPS with token
git config --global credential.helper store
echo "https://x-access-token:${TOKEN}@github.com" > ~/.git-credentials

# SSH
ssh-add ~/.ssh/id_ed25519

Next Steps

• GitHub integration details
• CHANGE_REQUEST mode
• Authentication guide