Commit message guidelines

commit-message-guidelines.md

Commit Message Guidelines

Short (72 chars or less) summary

More detailed explanatory text. Wrap it to 72 characters. The blank
line separating the summary from the body is critical (unless you omit
the body entirely).

Write your commit message in the imperative: "Fix bug" and not "Fixed
bug" or "Fixes bug." This convention matches up with commit messages
generated by commands like git merge and git revert.

Further paragraphs come after blank lines.

- Bullet points are okay, too.
- Typically a hyphen or asterisk is used for the bullet, followed by a
  single space. Use a hanging indent.

Example for a commit message

Add CPU arch filter scheduler support

In a mixed environment of…

A properly formed git commit subject line should always be able to complete the following sentence

If applied, this commit will <your subject line here>

Rules for a great git commit message style

• Separate subject from body with a blank line
• Do not end the subject line with a period
• Capitalize the subject line and each paragraph
• Use the imperative mood in the subject line
• Wrap lines at 72 characters
• Use the body to explain what and why you have done something. In most cases, you can leave out details about how a change has been made.

Information in commit messages

• Describe why a change is being made.
• How does it address the issue?
• What effects does the patch have?
• Do not assume the reviewer understands what the original problem was.
• Do not assume the code is self-evident/self-documenting.
• Read the commit message to see if it hints at improved code structure.
• The first commit line is the most important.
• Describe any limitations of the current code.
• Do not include patch set-specific comments.

Details for each point and good commit message examples can be found on https://wiki.openstack.org/wiki/GitCommitMessages#Information_in_commit_messages

References in commit messages

If the commit refers to an issue, add this information to the commit message header or body. e.g. the GitHub web platform automatically converts issue ids (e.g. #123) to links referring to the related issue. For issues tracker like Jira there are plugins which also converts Jira tickets, e.g. Jirafy.

In header:

[#123] Refer to GitHub issue…

CAT-123 Refer to Jira ticket with project identifier CAT…

In body:

…
Fixes #123, #124

Sources

• http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html
• https://wiki.openstack.org/wiki/GitCommitMessages
• http://chris.beams.io/posts/git-commit/

@Ahmed654321653 What is that, now?

What is the generally accepted practice if a commit contains numerous unrelated changes that cannot be described succinctly in just 50 characters?

Apply the "Single Responsability Principle" to the commit: split it into smaller logically self-contained commits whose contents can be explained in 50 chars.

I try to stick to that pattern but I sometimes take shortcuts when the cost or splitting is too high or the risk of changing several unrelated things at once is small.

Minimalistic approach :

[Action] Short summary (50 chars or less, this is the subject)

(optional) #Issue

More detailed explanatory text, if necessary. Maximun 80 characters to
wrap it.

- Hypen for bullet points.

Use the imperative mood in the subject line

Grammar nitpick: bare infinitive (i.e. "to ", but without the "to"), not imperative. They do look the same, but it's not a command here, it's a description of what will happen when the commit is merged.