Authoring Module Reference

The authoring module controls how commit author information is handled.

Functions

authoring.pass_thru

Preserve original author when possible:

authoring.pass_thru(
    default = "Bot <bot@example.com>",  # Fallback author
)

authoring.overwrite

Replace all authors:

authoring.overwrite(
    "Bot <bot@example.com>",            # Author for all commits
)

authoring.allowed

Allow specific authors, default for others:

authoring.allowed(
    default = "Bot <bot@example.com>",  # Fallback author
    allowlist = [                       # Preserved authors
        "alice@example.com",
        "bob@example.com",
    ],
)

Author Format

Authors use Git standard format:

Name <email@example.com>

Examples

Open Source Export

authoring = authoring.pass_thru(
    default = "Open Source Bot <oss@company.com>",
)

Bot-Only Commits

authoring = authoring.overwrite(
    "Sync Bot <sync@company.com>",
)

Allow Internal Team

authoring = authoring.allowed(
    default = "External <external@company.com>",
    allowlist = [
        "*@company.com",
    ],
)

Allowlist Patterns

The allowlist parameter supports glob-style patterns:

Pattern	Matches
`alice@example.com`	Exact email match
`*@company.com`	Any email at company.com
`@.company.com`	Any subdomain email

Behavior Details

What Happens When Author Doesn’t Match

When using authoring.allowed and an author isn’t in the allowlist:

Commit is attributed to the default author
Original author is preserved in the commit message body (configurable)
The transformation continues normally

Malformed Authors

If the source commit has a malformed author (missing email, empty name), Copybara uses the default author.

Author vs Committer

Git distinguishes between author (who wrote the code) and committer (who applied it). Copybara’s authoring module affects the author field. The committer is typically the user/bot running Copybara.

Common Use Cases

Use Case	Authoring Mode
Open source export (preserve contributors)	`pass_thru`
Automated sync (bot attribution)	`overwrite`
Internal → External (allow known devs)	`allowed`
Mirror (exact copy)	`pass_thru`