pr-log

Changelog generator based on GitHub Pull Requests


pr-log

Changelog generator based on GitHub Pull Requests

The main features:

  • Writes in a CHANGELOG.md from merged GitHub pull requests since the last tag. This works by
    • first getting a list of all tags
    • than removing all tags that are not compatible to semver versioning
    • sort the tags
    • getting the git log from the last tag until now
    • If no CHANGELOG.md existed, it will create the file else it will write prepending to it
  • Friendly CLI
    • Get usage by running pr-log --help
    • Error messages that help correcting usage mistakes. E.g.
      • Missing first command line argument: Error: version-number not specified
      • Local branch is outdated compared to the remote branch: Error: Local git master branch is 0 commits ahead and 2 commits behind of origin/master
      • The current working directory is not clean (e.g. contains files that are modified): Error: Local copy is not clean
  • Well tested

Install

Simply run this to install pr-log:

npm install pr-log

Setup and configuration

You have to follow these steps to use pr-log without problems.

GitHub

The following categories are defined by default:

GitHub label Human friendly name Description
breaking Breaking Changes Backwards-incompatible changes
bug Bug Fixes Changes that only fix a bug
feature Features New features
enhancement Enhancements Non-breaking improvements of existing features
documentation Documentation Changes to documentation and/or README
upgrade Dependency Upgrades Any kind of dependency updates
refactor Code Refactoring Changes that don’t affect the behavior but improve the code quality
build Build-Related Changes related to the build process and/or CI/CD pipeline

However, you can also create a custom mapping by adding a pr-log.validLabels section to your package.json. validLabels must be specified as an array of key, value pairs. The same order will be used to format the changelog sections. For example:

{
  "pr-log": {
    "validLabels": [
      [ "core", "Core features" ],
      [ "addon", "Addons" ]
    ]
  }
}

To use pr-log your GitHub project needs some small configuration:

  • Create the labels mentioned above (you can create GitHub labels from Issues -> Labels -> New Label)
  • Set the correct label on your pull requests - you need to set exactly one label, multiple labels or one that is not recognized will throw an error
  • Use correct semver versioning for your tags (e.g. 2.4.7)

Project

As pr-log reads repository information from your project you have to add the repository information in your package.json

{
  "repository": {
    "type": "git",
    "url": "https://github.com/<your username>/<your repository name>.git"
  }
}

Changelog formatting

Custom date format

If you want to use a custom date format you can configure pr-log.dateFormat in your package.json. For example:

{
  "pr-log": { "dateFormat": "DD.MM.YYYY" }
}

Please refer to the moment.js documentation for details about the format tokens.

Usage

To create or update your changelog run

pr-log [options] <version-number> where version-number is the name of this release

Example:

Given the following setup:

  • In GitHub a tag named 2.0.0 exists that is behind master
  • A pull request (#13) was created since the last tag that has the label breaking
  • A pull request (#22) was created since the last tag that has the label documentation

pr-log 2.0.0 creates a changelog with the following example content:

## 2.0.0 (January 20, 2015)

### Breaking Changes

* Use new (backwards incompatible) version of module XYZ (#13)

### Documentation

* Fix some spelling mistakes in documentation. (#22)

Options

--sloppy

The --sloppy option defaults to false. When set, it allows pr-log to generate a changelog even when you are not on the master branch. This should not be used in production!

--trace

When enabled this option outputs the stacktrace of an error additionally to the error message to stderr.

Correct usage makes a clean and complete changelog

If you want your changelog to be complete and clean you have to follow these rules:

  1. Don't commit directly to master - if you do, your changes will not be covered in the changelog (this might be ok but you should know this implication)
  2. Use pull requests for your features that you want to be in your changelog
  3. Use the correct categories for your pull request: If you introduce a new feature that will be a breaking change, give it the according label breaking (which will later result in this feature being listed under the Breaking Changes point in your changelog)

Github Authentication

If you need to authenticate pr-log, e.g. to access a private repo, you can set the GH_TOKEN environment variable. Generate a token value in your Github settings.

GH_TOKEN=xxxxxxxxx pr-log [options] <version-number>

Reason for this project

Many projects have problems with their changelogs. Most of them try one of the following ways

  • manually write change logs: This is error-prone and the log will not be consistent
  • generating it from commit messages: As there are often far more commits than useful messages for the changelog, this will hide important features because there are too many to read everything

Other challenges for good changelogs:

  • Different categories (e.g. breaking changes)
  • Only include changes starting from a certain tag

More complete example CHANGELOG.md

After working for some time with the tool and having e.g. two releases, the file content could look like this:

## 2.0.0 (January 20, 2015)

### Breaking Changes

* Use new (backwards incompatible) version of module XYZ (#13)

### Features

* Add fancy feature (#2)
*
### Documentation

* Fix some spelling mistakes in documentation. (#22)

## 1.1.0 (November 3, 2014)

Repository

https://github.com/lo1tuma/pr-log.git


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