git-changelog is a tool to automate repository changelog generation.
A commit like this generates an output like this.
Motivation
Commit messages must always be meaningful and with a little extra effort we can automate the chore of generating meaningful change logs for our users. As I finish up work on a change to a repository, I like to pause a while, consider what the change means to the end-user and reorganize the message a bit. If you follow the (easy) conventions described below and tag lines in your commit message appropriately, this tool will help you generate an accurate and presentable change log.
A little time spent at commit, when the context and impact of the change is fresh in mind, saves a lot of time at release milestones.
Installation
> cargo
If you use a Mac with Homebrew, you may prefer the following:
> brew
> brew
Both options build the executable from sources. If you're looking for just the executables, they're attached to the releases.
Usage
Just write your commits as you normally do. When it looks like a particular commit includes a change that the "user" may be interested in, tag its lines appropriately.
Concretely, instead of writing this:
Add support for filtering responses
UI gets a bit cluttered when the response contains too many
items. Added a simple filtering scheme to reduce the result
set to a more relevant subset. Clients using v1.2 need to
upgrade to accomodate the new request parameter.
Write this:
Add support for filtering responses
- feature: UI gets a bit cluttered when the response
contains too many items. Added a simple filtering scheme
to reduce the result set to a more relevant subset.
- break: Clients using v1.2 need to upgrade to accommodate
the new request parameter.
The two commit messages are almost the same but the latter tags user visible changes a bit more diligently. Eventually, this diligence helps the tool to identify lines, aggregate similar things (e.g. breaking changes) across commits, order them, and give you a report that you can share, as is, with users. Or, you can use the output as the starting draft, make editorial changes and then share it with users. Either way, it saves you some time.
Of course, you don't need to tag every commit (git commit -m is perfectly fine, where you
think it is). You just need to tag the changes you want your users to know about. The quality of the
tool output depends on the quality of your input.
Generate reports
When git-changelog is on the path, git changelog works just like git log and takes similar
arguments. Concretely, it takes a commit range and looks for all commits in that range and uses
the tags it finds in their messages to generate a report. Simple. :)
The default revision range picks all commits made since the last tag. For example, to generate the
changelog for v0.2.0 of the tool, I used the following:
> git
The command picks all commits since v0.1.1 (the current last tag) and generates a change report that I pasted verbatim to the CHANGELOG.md.
Customization
Each project is different and you may want to customize the tags and output to suit your requirements. You can do that by adding a .changelog.yml file to your repository root. See the default configuration file for a starting example.
If you like to tweak the output, you can specify a Handlebars template to control the rendered
report format (using template key in your .changelog.yml). The default
template generates a Markdown document that renders well on Github.