Gerrit Change-Id Hooks

A minimally modified Gerrit commit-msg hook that automatically adds a Change-Id footer to Git commit messages.

This repository also includes a prepare-commit-msg hook to support commits created with git revert.

Included Hooks

commit-msg
prepare-commit-msg

commit-msg

Generates and inserts a Gerrit Change-Id into the commit message footer.

prepare-commit-msg

Detects commit messages created by git revert and runs the commit-msg hook before the revert commit is finalized.

Installation

Run the following commands from the root directory of your Git repository:

mkdir -p .git/hooks

curl -fsSL \
  https://raw.githubusercontent.com/greenforce-project/commit-msg/main/commit-msg \
  -o .git/hooks/commit-msg

curl -fsSL \
  https://raw.githubusercontent.com/greenforce-project/commit-msg/main/prepare-commit-msg \
  -o .git/hooks/prepare-commit-msg

chmod +x .git/hooks/commit-msg
chmod +x .git/hooks/prepare-commit-msg

Verify the installation:

ls -l .git/hooks/commit-msg .git/hooks/prepare-commit-msg

Validate the shell syntax:

sh -n .git/hooks/commit-msg
sh -n .git/hooks/prepare-commit-msg

No output means the syntax is valid.

Usage

After installation, use Git normally.

How To Commit

git add .
git commit -m "kernel: update scheduler configuration"

Check the generated commit message:

git show -s --format=%B HEAD

Expected result:

kernel: update scheduler configuration

Change-Id: Ixxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Amend an Existing Commit

To add a missing Change-Id to the latest commit:

git commit --amend --no-edit

The hook preserves the existing commit message and adds a new Change-Id if one does not already exist.

Check the result:

git show -s --format=%B HEAD

Configuration

To always generate a Change-Id, including for fixup and squash commits:

git config gerrit.createChangeId always

Apply the setting globally:

git config --global gerrit.createChangeId always

Check the current setting:

git config --get gerrit.createChangeId

Expected output:

always

To disable automatic Change-Id generation for the current repository:

git config gerrit.createChangeId false

Remove the local configuration:

git config --unset gerrit.createChangeId

Updating the Hooks

Run these commands from the root of the target repository:

curl -fsSL \
  https://raw.githubusercontent.com/greenforce-project/commit-msg/main/commit-msg \
  -o .git/hooks/commit-msg

curl -fsSL \
  https://raw.githubusercontent.com/greenforce-project/commit-msg/main/prepare-commit-msg \
  -o .git/hooks/prepare-commit-msg

chmod +x .git/hooks/commit-msg
chmod +x .git/hooks/prepare-commit-msg

Troubleshooting

Change-Id Is Not Generated

Check whether the hook exists:

ls -l .git/hooks/commit-msg

Make sure it is executable:

chmod +x .git/hooks/commit-msg

Check whether automatic generation is disabled:

git config --get gerrit.createChangeId

If the result is false, enable it:

git config gerrit.createChangeId always

Revert Commit Has No Change-Id

Check whether prepare-commit-msg is installed:

ls -l .git/hooks/prepare-commit-msg

Make it executable:

chmod +x .git/hooks/prepare-commit-msg

For an already-created revert commit:

git commit --amend --no-edit

Hook Syntax Error

Validate both hook files:

sh -n .git/hooks/commit-msg
sh -n .git/hooks/prepare-commit-msg

Existing Hook Files

Back up existing hooks before installation:

cp .git/hooks/commit-msg .git/hooks/commit-msg.backup 2>/dev/null || true
cp .git/hooks/prepare-commit-msg .git/hooks/prepare-commit-msg.backup 2>/dev/null || true

Uninstallation

Remove both hooks:

rm -f .git/hooks/commit-msg
rm -f .git/hooks/prepare-commit-msg

Remove the local Gerrit configuration if needed:

git config --unset gerrit.createChangeId

Notes

• Git hooks are stored inside .git/hooks and are not committed with the target project repository.
• Each developer must install the hooks in their local clone.
• Existing Change-Id footers are preserved.
• A Gerrit Change-Id is different from a Git commit hash.
• Amending a commit preserves its existing Change-Id.