| commit-msg Hook |
| =============== |
| |
| NAME |
| ---- |
| commit-msg - Edit commit messages to insert a `Change-Id` tag. |
| |
| DESCRIPTION |
| ----------- |
| |
| A Git hook automatically invoked by `git commit`, and most other |
| commit creation tools such as `git citool` or `git gui`. The Gerrit |
| Code Review supplied implementation of this hook is a short shell |
| script which automatically inserts a globally unique Change-Id tag |
| in the footer of a commit message. When present, Gerrit uses this |
| tag to track commits across cherry-picks and rebases. |
| |
| After the hook has been installed in the user's local Git repository |
| for a project, the hook will modify a commit message such as: |
| |
| ---- |
| Improve foo widget by attaching a bar. |
| |
| We want a bar, because it improves the foo by providing more |
| wizbangery to the dowhatimeanery. |
| |
| Signed-off-by: A. U. Thor <author@example.com> |
| ---- |
| |
| by inserting a new `Change-Id: ` line in the footer: |
| |
| ---- |
| Improve foo widget by attaching a bar. |
| |
| We want a bar, because it improves the foo by providing more |
| wizbangery to the dowhatimeanery. |
| |
| Change-Id: Ic8aaa0728a43936cd4c6e1ed590e01ba8f0fbf5b |
| Signed-off-by: A. U. Thor <author@example.com> |
| ---- |
| |
| The hook implementation is reasonably intelligent at inserting the |
| Change-Id line before any Signed-off-by or Acked-by lines placed |
| at the end of the commit message by the author, but if no such |
| lines are present then it will just insert a blank line, and add |
| the Change-Id at the bottom of the message. |
| |
| If a Change-Id line is already present in the message footer, the |
| script will do nothing, leaving the existing Change-Id unmodified. |
| This permits amending an existing commit, or allows the user to |
| insert the Change-Id manually after copying it from an existing |
| change viewed on the web. |
| |
| OBTAINING |
| --------- |
| To obtain the 'commit-msg' script use scp to copy it to your |
| local system: |
| |
| $ scp -p -P 29418 review.example.com:hooks/commit-msg .git/hooks/ |
| |
| SEE ALSO |
| -------- |
| |
| * link:user-changeid.html[Change-Id Lines] |
| * link:http://www.kernel.org/pub/software/scm/git/docs/git-commit.html[git-commit(1)] |
| * link:http://www.kernel.org/pub/software/scm/git/docs/githooks.html[githooks(5)] |
| |
| IMPLEMENTATION |
| -------------- |
| |
| The hook generates unique Change-Id lines by creating a virtual |
| commit object within the local Git repository, and obtaining the |
| SHA-1 hash from it. Like any other Git commit, the following |
| properties are included in the computation: |
| |
| * SHA-1 of the tree being committed |
| * SHA-1 of the parent commit |
| * Name, email address, timestamp of the author |
| * Name, email address, timestamp of the committer |
| * Proposed commit message (before Change-Id was inserted) |
| |
| Because the names of the tree and parent commit, as well as the |
| committer timestamp are included in the hash computation, the output |
| Change-Id is sufficiently unique. |
| |
| GERRIT |
| ------ |
| Part of link:index.html[Gerrit Code Review] |
