5.5. Commit Message

Commits are used as a source of truth for various reports. A couple of examples are:

  • Release Notes
  • Issues resolved for QA to plan the QA cycle.

To be able to generate these reports, uniform commit messages are required. All your commits should follow the following convention:

For every commit please write a short (max 72 characters) summary in the first line followed with a blank line and then more detailed descriptions of the change.

Format of summary:



ACTION is one of 'chg', 'fix', 'new'
Is WHAT the change is about.
'chg' is for refactor, small improvement, cosmetic changes...
'fix' is for bug fixes
'new' is for new features, big improvement

AUDIENCE is one of 'dev', 'usr', 'pkg', 'test', 'doc'
Is WHO is concerned by the change.
'dev' is for developers (API changes, refactors...)
'usr' is for final users

You will use your environment’s default editor (EDITOR=vi|emacs) to compose the commit message. Do NOT use the command line git commit -m “my mesg” as this only allows you to write a single line that most of the times turns out to be useless to others reading or reviewing your commit.


new: dev: #124: report liveness metric for BookKeeper daemon (#139)

Add a liveness gauge that the daemon is up & alive. Right now, this 
is a simple check that a thread (reporter to be added in a subsequent 
commit) is alive. In the future, this simple framework will be used 
to add more comprehensive health checks. Ref: #140

The above example shows the commit summary is:

  • a single line composed of four columns
  • column 1 tells us the nature of the change or ACTION: new
  • a short one-line summary of WHAT the commit is doing

The description or the body of the commit message delves into more detail that is intended to serve as a history for developers on the team on how the code is evolving. There are more immediate uses of this description however. When you raise pull requests to make your contributions into the project, your commit descriptions serve as explanations of WHY you fixed an issue. HOW you fixed an issue is explained by code already. This is also the place where the peer-reviewers will begin understanding your code. An unclear commit message is the source of a lot of back and forth resulting in frustration between reviewers and committers.

Reference: http://chris.beams.io/posts/git-commit/