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GeezerVison is showing github.com — Add trailer support for commit creation by Krishnachaitanyakc · Pull Request #2116 · gitpython-developers/GitPython

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Krishnachaitanyakc commented Mar 25, 2026

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Summary

Adds a trailers parameter to Commit.create_from_tree() and IndexFile.commit() enabling trailer creation (e.g. Signed-off-by, Issue) when committing programmatically
Accepts either a dict or a list of (key, value) tuples (for duplicate keys like multiple Signed-off-by)
Uses git interpret-trailers for formatting, consistent with existing trailer parsing in Commit.trailers_list

Closes #1998

Motivation

GitPython already supports parsing trailers from existing commits, but did not support adding them when creating new commits. The git commit CLI supports this via --trailer, e.g.:

git commit --message "Did a thing" --trailer "Issue: abc"

This change brings equivalent functionality to GitPython's Python API.

Usage

# Using a dict
repo.index.commit("Fix bug", trailers={"Issue": "123"})

# Using a list of tuples (for duplicate keys)
repo.index.commit("Fix bug", trailers=[
    ("Signed-off-by", "Alice <[email protected]>"),
    ("Signed-off-by", "Bob <[email protected]>"),
])

# Via Commit.create_from_tree directly
Commit.create_from_tree(repo, tree, "Fix bug", trailers={"Reviewed-by": "Eve"})

Test plan

test_create_from_tree_with_trailers_dict - verifies dict-based trailer creation and round-trip parsing
test_create_from_tree_with_trailers_list - verifies list-of-tuples trailer creation with duplicate keys
test_index_commit_with_trailers - verifies IndexFile.commit() passes trailers through correctly
All 3 new tests pass locally

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          Add trailer support for commit creation

7c5fbc6

Add a `trailers` parameter to `Commit.create_from_tree()` and
`IndexFile.commit()` that allows appending trailer key-value pairs
(e.g. Signed-off-by, Issue) to the commit message at creation time.

Trailers can be passed as either a dict or a list of (key, value) tuples,
the latter being useful when duplicate keys are needed. The implementation
uses `git interpret-trailers` for proper formatting, consistent with
the existing trailer parsing in `Commit.trailers_list`.

Closes gitpython-developers#1998

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March 25, 2026 12:01

Byron commented Mar 25, 2026

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March 25, 2026 12:01

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Pull request overview

Adds support for creating commit trailers when programmatically generating commits, aligning commit creation with GitPython’s existing trailer parsing capabilities.

Changes:

Add a trailers parameter to Commit.create_from_tree() to append trailers via git interpret-trailers.
Thread trailers through IndexFile.commit() so index commits can include trailers.
Add tests covering dict-based trailers, list-of-tuples trailers (duplicate keys), and the index commit plumbing.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
`git/objects/commit.py`	Adds `trailers` support in `Commit.create_from_tree()` by invoking `git interpret-trailers`.
`git/index/base.py`	Exposes `trailers` in `IndexFile.commit()` and forwards it to `Commit.create_from_tree()`.
`test/test_commit.py`	Adds round-trip tests validating trailer creation and parsing for both APIs.

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git/objects/commit.py Resolved

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git/objects/commit.py Resolved

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Byron approved these changes

Mar 25, 2026

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Thanks a lot, this looks good to me.

The Copilot comments should be addressed and then it can be merged.

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Krishnachaitanyakc commented Apr 6, 2026

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@Byron addressed those comments, can you please review?

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Byron commented Apr 6, 2026

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It doesn't look like they are resolved, nor was anything pushed. Please also resolve them. Thank you.

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          Use configured git executable and finalize process for trailer creation

af0933c

Krishnachaitanyakc force-pushed the add-trailer-support-for-commit-creation branch from 4da170c to af0933c Compare

April 6, 2026 15:59

Krishnachaitanyakc commented Apr 6, 2026

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@Byron sorry, missed pushing them. Can you review now?

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Byron requested a review from Copilot

April 12, 2026 22:36

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April 12, 2026 22:37

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Thanks a lot, looks good to me!

It's a shame that it's shelling out to build a string, but better to have a slow but correct version, than nothing at all in that regard.

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Byron merged commit b5b87dd into gitpython-developers:main

Apr 12, 2026

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Apr 12, 2026

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Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

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git/objects/commit.py

Comment on lines +708 to +710

		stdout_bytes, _ = proc.communicate(str(message).encode())
		finalize_process(proc)
		message = stdout_bytes.decode("utf8")

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interpret-trailers I/O is hard-coded to UTF-8 (.encode() default + .decode('utf8')), but this method already resolves conf_encoding for the commit’s declared encoding. If i18n.commitencoding is not UTF-8, this can raise decode errors or corrupt non-ASCII characters; use the resolved encoding for both encoding stdin and decoding stdout (and consider an explicit error strategy).

Suggested change

	stdout_bytes, _ = proc.communicate(str(message).encode())
	finalize_process(proc)
	message = stdout_bytes.decode("utf8")
	stdout_bytes, _ = proc.communicate(str(message).encode(conf_encoding, errors="strict"))
	finalize_process(proc)
	message = stdout_bytes.decode(conf_encoding, errors="strict")

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git/objects/commit.py

Comment on lines +707 to +709

		)
		stdout_bytes, _ = proc.communicate(str(message).encode())
		finalize_process(proc)

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This uses as_process=True, which makes Git.execute(..., with_exceptions=True) ineffective (see Git.execute docs), but the code never checks proc.returncode / stderr after communicate(). If interpret-trailers fails (e.g., unsupported --trailer on an older Git), message may be replaced with empty/partial stdout and the commit is still created; please detect non-zero exit status and raise (or preserve the original message on failure).

Suggested change

	)
	stdout_bytes, _ = proc.communicate(str(message).encode())
	finalize_process(proc)
	stderr=PIPE,
	)
	stdout_bytes, stderr_bytes = proc.communicate(str(message).encode())
	finalize_process(proc)
	if proc.returncode:
	stderr = stderr_bytes.decode("utf8", errors="replace") if stderr_bytes else ""
	raise RuntimeError(
	"git interpret-trailers failed with exit code "
	f"{proc.returncode}: {stderr or 'no error output'}"
	)

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git/objects/commit.py

Comment on lines +702 to +704

		cmd = [repo.git.GIT_PYTHON_GIT_EXECUTABLE, "interpret-trailers"] + trailer_args
		proc: Git.AutoInterrupt = repo.git.execute( # type: ignore[call-overload]
		cmd,

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The command uses repo.git.GIT_PYTHON_GIT_EXECUTABLE here, but Commit.trailers_list/trailers_dict currently invoke interpret-trailers via a hard-coded ['git', ...]. If a caller overrides GIT_PYTHON_GIT_EXECUTABLE, trailer creation and trailer parsing can end up using different Git binaries; consider aligning both paths on the same executable selection approach for consistent round-trips.

Suggested change

	cmd = [repo.git.GIT_PYTHON_GIT_EXECUTABLE, "interpret-trailers"] + trailer_args
	proc: Git.AutoInterrupt = repo.git.execute( # type: ignore[call-overload]
	cmd,
	proc: Git.AutoInterrupt = repo.git._call_process( # type: ignore[attr-defined]
	"interpret-trailers",
	*trailer_args,

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Copilot AI mentioned this pull request

Apr 12, 2026

Harden commit trailer subprocess handling and align trailer I/O paths #2125

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736-c41-2c1-e464fc974 pushed a commit to Swiss-Armed-Forces/Loom that referenced this pull request

Apr 27, 2026


          chore(deps): update dependency gitpython to v3.1.47

20381c1

This MR contains the following updates:

| Package | Type | Update | Change | OpenSSF |
|---|---|---|---|---|
| [gitpython](https://github.com/gitpython-developers/GitPython) | dev | patch | `3.1.46` → `3.1.47` | [![OpenSSF Scorecard](https://api.securityscorecards.dev/projects/github.com/gitpython-developers/GitPython/badge)](https://securityscorecards.dev/viewer/?uri=github.com/gitpython-developers/GitPython) |

---

### Release Notes

<details>
<summary>gitpython-developers/GitPython (gitpython)</summary>

### [`v3.1.47`](https://github.com/gitpython-developers/GitPython/releases/tag/3.1.47): - with security fixes

[Compare Source](gitpython-developers/GitPython@3.1.46...3.1.47)

#### Advisories

- <GHSA-rpm5-65cw-6hj4>
- <GHSA-x2qx-6953-8485>

#### What's Changed

- Prepare next release by [@&#8203;Byron](https://github.com/Byron) in [#&#8203;2095](gitpython-developers/GitPython#2095)
- Bump git/ext/gitdb from `335c0f6` to `4c63ee6` by [@&#8203;dependabot](https://github.com/dependabot)\[bot] in [#&#8203;2096](gitpython-developers/GitPython#2096)
- DOC: README Add urls and updated a relative url by [@&#8203;Timour-Ilyas](https://github.com/Timour-Ilyas) in [#&#8203;2098](gitpython-developers/GitPython#2098)
- Fix GitConfigParser ignoring multiple \[include] path entries by [@&#8203;daniel7an](https://github.com/daniel7an) in [#&#8203;2100](gitpython-developers/GitPython#2100)
- Switch back from Alpine to Debian for WSL by [@&#8203;EliahKagan](https://github.com/EliahKagan) in [#&#8203;2108](gitpython-developers/GitPython#2108)
- Bump git/ext/gitdb from `4c63ee6` to `5c1b303` by [@&#8203;dependabot](https://github.com/dependabot)\[bot] in [#&#8203;2106](gitpython-developers/GitPython#2106)
- Run `gc.collect()` twice in `test_rename` on Python 3.12 by [@&#8203;EliahKagan](https://github.com/EliahKagan) in [#&#8203;2109](gitpython-developers/GitPython#2109)
- fix: guard AutoInterrupt terminate during interpreter shutdown by [@&#8203;lweyrich1](https://github.com/lweyrich1) in [#&#8203;2105](gitpython-developers/GitPython#2105)
- Improve CI infrastructure for pre-commit by [@&#8203;EliahKagan](https://github.com/EliahKagan) in [#&#8203;2110](gitpython-developers/GitPython#2110)
- Bump the pre-commit group with 5 updates by [@&#8203;dependabot](https://github.com/dependabot)\[bot] in [#&#8203;2111](gitpython-developers/GitPython#2111)
- Upgrade Sphinx for 3.14 support; drop doc build support on 3.8; test 3.14 by [@&#8203;EliahKagan](https://github.com/EliahKagan) in [#&#8203;2112](gitpython-developers/GitPython#2112)
- Fix `Repo.active_branch` resolution for reftable-backed repositories by [@&#8203;Copilot](https://github.com/Copilot) in [#&#8203;2114](gitpython-developers/GitPython#2114)
- docs: warn about GitDB performance with large commits by [@&#8203;mvanhorn](https://github.com/mvanhorn) in [#&#8203;2115](gitpython-developers/GitPython#2115)
- cmd: fix kwarg formatting in docstring example by [@&#8203;UweSchwaeke](https://github.com/UweSchwaeke) in [#&#8203;2117](gitpython-developers/GitPython#2117)
- Bump <https://github.com/astral-sh/ruff-pre-commit> from v0.15.5 to 0.15.8 in the pre-commit group by [@&#8203;dependabot](https://github.com/dependabot)\[bot] in [#&#8203;2122](gitpython-developers/GitPython#2122)
- Add trailer support for commit creation by [@&#8203;Krishnachaitanyakc](https://github.com/Krishnachaitanyakc) in [#&#8203;2116](gitpython-developers/GitPython#2116)
- Harden commit trailer subprocess handling and align trailer I/O paths by [@&#8203;Copilot](https://github.com/Copilot) in [#&#8203;2125](gitpython-developers/GitPython#2125)
- git.cmd.Git.execute(..): fix `with_stdout=False` by [@&#8203;ngie-eign](https://github.com/ngie-eign) in [#&#8203;2126](gitpython-developers/GitPython#2126)
- Make sure that multi-options are checked after splitting them with `shlex` by [@&#8203;Byron](https://github.com/Byron) in [#&#8203;2130](gitpython-developers/GitPython#2130)
- Block unsafe underscored git kwargs / Fix for GHSA-rpm5-65cw-6hj4 by [@&#8203;WesR](https://github.com/WesR) in [#&#8203;2131](gitpython-developers/GitPython#2131)

#### New Contributors

- [@&#8203;Timour-Ilyas](https://github.com/Timour-Ilyas) made their first contribution in [#&#8203;2098](gitpython-developers/GitPython#2098)
- [@&#8203;daniel7an](https://github.com/daniel7an) made their first contribution in [#&#8203;2100](gitpython-developers/GitPython#2100)
- [@&#8203;lweyrich1](https://github.com/lweyrich1) made their first contribution in [#&#8203;2105](gitpython-developers/GitPython#2105)
- [@&#8203;Copilot](https://github.com/Copilot) made their first contribution in [#&#8203;2114](gitpython-developers/GitPython#2114)
- [@&#8203;mvanhorn](https://github.com/mvanhorn) made their first contribution in [#&#8203;2115](gitpython-developers/GitPython#2115)
- [@&#8203;UweSchwaeke](https://github.com/UweSchwaeke) made their first contribution in [#&#8203;2117](gitpython-developers/GitPython#2117)
- [@&#8203;Krishnachaitanyakc](https://github.com/Krishnachaitanyakc) made their first contribution in [#&#8203;2116](gitpython-developers/GitPython#2116)
- [@&#8203;ngie-eign](https://github.com/ngie-eign) made their first contribution in [#&#8203;2126](gitpython-developers/GitPython#2126)
- [@&#8203;WesR](https://github.com/WesR) made their first contribution in [#&#8203;2131](gitpython-developers/GitPython#2131)

**Full Changelog**: <gitpython-developers/GitPython@3.1.46...3.1.47>

</details>

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this MR, check this box

---

This MR has been generated by [Mend Renovate](https://github.com/renovatebot/renovate).
<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiI0My4xNDEuNSIsInVwZGF0ZWRJblZlciI6IjQzLjE0MS41IiwidGFyZ2V0QnJhbmNoIjoibWFpbiIsImxhYmVscyI6WyJkZXBlbmRlbmNpZXMiLCJyZW5vdmF0ZSJdfQ==-->

See merge request swiss-armed-forces/cyber-command/cea/loom!486

Co-authored-by: Loom MR Pipeline Trigger <group_103951964_bot_9504bb8dead6d4e406ad817a607f24be@noreply.gitlab.com>

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