Keep a CHANGELOG
Don’t let your friends dump git logs into CHANGELOGs™
What's a CHANGELOG?
A CHANGELOG is a file which contains a curated chronologically ordered list of notable changes for each version of an open source project.
What's the point of a CHANGELOG?
To make it easier for users and contributors to see precisely what notable changes have been made between each release (or version) of the project.
What makes up a good CHANGELOG?
I'm glad you asked.
- It's made for humans, not machines, so legibility is crucial.
- One sub-section per versions.
- Versions should come with a release date in a sensible format: YYYY-MM-DD.
- Changes should be grouped to describe their impact on the project:
Addedfor new features.
Deprecatedfor once stable features removed in upcoming releases.
Removedfor deprecated features removed in this release.
Fixedfor any bug fixes.
Securityto invite users to upgrade in case of vulnerabilities.
- Each section should be easily linked to — hence Markdown over plain text.
- Write release dates in an international, sensible, and
June 2nd, 2012.
- Order the releases reverse chronologically (latest at the top).
It's also good to mention whether the project follows Semantic Versioning.
What makes unicorns cry?
Alright, let's get into it:
- Dumping a diff of commit logs. Just don't do that, you're helping nobody.
- Not emphasizing deprecations: when people upgrade from one version to another it should be painfully clear when something will break.
- Dates in regionally-specific formats. Americans put the month first ("06-02-2012" for June 2nd, 2012, which makes no sense), while Brits use a robotic-looking "June 2 2012", yet pronounce it "June 2nd, 2012".
There's more. Help me collect those unicorn tears by opening an issue or a pull request.
Is there a standard CHANGELOG format?
Sadly, no, but this is something I want to change. This project contains what I hope will become the standard CHANGELOG file for all open source projects, so take a look at it and please suggest improvements.
What should the CHANGELOG file be named?
Well, if you can't tell from the example above,
CHANGELOG.md is the
best convention so far.
Some projects also use
It's a mess, that only makes it harder for people to find it.
Why can't people just use a git log diff?
Because log diffs are full of noise. Can we really expect every single commit in an open source project to be meaningful and self-explanatory? That seems like a pipe dream.
Can CHANGELOG files be automatically parsed?
It's hard because people follow wildly different formats and file names. Vandamme is a Ruby gem created by the Gemnasium team and which parses many (but not all) open source project CHANGELOGs.
Why do you keep writing CHANGELOG in all caps?
You're right, that is a bit shouty. Maybe it's because of the de facto
convention that files pertaining to an open source project should be in
all caps, for instance:
It denotes that these files are metadata for the project, similarly to open source project badges they draw attention to themselves as information people should be aware of if they mean to use the project or contribute to it.
How can I contribute?
This document is not the truth, it's my carefully considered opinion with the information and examples I was able to gather. Although I provide an actual CHANGELOG on the GitHub repo, I have purposefully not created a proper release or clear list of rules to follow like SemVer.org does for instance. This is because I want our community to reach a consensus. I believe the discussion is as important as the end result. So please pitch in.