Generates a changelog from GitHub issues and pull-requests.

This project is similar (in functionality and output) to the great GitHub Changelog Generator, but as a Gradle plugin.

When applied, the plugin automatically adds the generateChangelog task. This task calls GitHub to get information about your issues and pull requests, and generates a CHANGELOG.md file in your project's root folder.

The releases in the changelog are determined by the git tags of the repository. The date of the release is the date of the tag.

Closed issues are sorted into releases using their close date, but this behaviour can be overridden. More specifically, the following rules apply (by order of precedence):

1. if the issue is forced into a tag via customTagByIssueNumber mapping, it is put under this tag
2. if the issue has a milestone, and the title of that milestone matches a git tag, then the issue is put under this tag
3. otherwise, the issue is put under the first tag that follows its close date

For example, all issues closed between the date of tag 1.0 and the date of the tag 1.1 are considered to be in release 1.1.

To see an example output, take a look at this project's CHANGELOG.md, which was generated with this plugin.

Within a given release, issues are sorted into sections based on their labels. Each issue label can be associated to at most one section, but a section can correspond to several labels. An issue is placed into a section according to the first of its labels that is associated to a section.

The default sections and the associated labels are:

• Breaking changes: backwards-incompatible, breaking
• New features: feature
• Implemented enhancements: enhancement
• Deprecations: deprecated, deprecation
• Removals: removed, removal
• Fixed bugs: bug
• Upgraded dependencies: dependency, dependency-upgrade, dependencies

If the list of issues itself is not enough, you can write a summary for a given release to describe the release further with full markdown capabilities.

To do so, you simply need to create a special issue:

• with the label release-summary
• with a milestone that has the same name as the release tag
• with a body that contains the description of the release that you want to appear

Then close this issue and run the changelog generator.

The changelog generation task also outputs a markdown file containing just the closed issues for the latest release (and the optional release summary), which is ideal for generating the latest release notes.

The default path to this file is $buildDir/reports/changelog/latest-release-body.md, and is customizable via the latestReleaseBodyFile extension property.

If you create a GitHub release from a GitHub Actions workflow, you can use this file as the body text of that release.

Add the following line to your plugins block (in the root project's build.gradle(.kts)):

plugins {
    id("org.hildan.github.changelog") version "<version>"
}

Where <version> is the desired version (see badge above without v prefix), e.g. 1.3.0.

Gradle compatibility:

The minimal required configuration is your GitHub username.

It can be provided in 3 different ways depending on your needs:

• the githubUser project property (add githubUser=user-or-org to gradle.properties)
• the GITHUB_USER environment variable
• the githubUser property of the changelog DSL (see below)

If you're using the project property or the environment variable, and stick with the defaults, you don't even need to define the changelog extension at all in your gradle file.

You can then simply run:

gradle generateChangelog

Here is the extension DSL with all options and their default values:

changelog {
    githubUser = // [mandatory] project property "githubUser" or env variable "GITHUB_USER"
    githubToken = null // [optional] project property "githubToken" or env variable "GITHUB_TOKEN"
    githubRepository = rootProject.name
    
    title = "Change Log"
    showUnreleased = true
    unreleasedVersionTitle = "Unreleased"
    futureVersionTag = null
    sections = [] // no custom sections by default, but default sections are prepended
    defaultIssueSectionTitle = "Closed issues:"
    defaultIssueSectionOrder = 60
    defaultPrSectionTitle = "Merged pull requests:"
    defaultPrSectionOrder = 70
    includeLabels = []
    excludeLabels = [
        "doc",
        "documentation",
        "duplicate",
        "internal",
        "invalid",
        "no-changelog",
        "question",
        "wontfix"
    ]
    sinceTag = null
    skipTags = []
    skipTagsRegex = []
    releaseUrlTemplate = null // defaults to "https://github.com/$user/$repo/tree/%s"
    diffUrlTemplate = null // defaults to "https://github.com/$user/$repo/compare/%s...%s"
    releaseUrlTagTransform = { it }
    diffUrlTagTransform = { it }
    customTagByIssueNumber = [:]
    useMilestoneAsTag = true
    timezone = ZoneId.of("GMT")
    
    outputFile = file("${projectDir}/CHANGELOG.md")
    latestReleaseBodyFile = file("$buildDir/reports/changelog/latest-release-body.md")
}

• githubUser: your GitHub username

• githubToken: your personal access token. It is required to generate changelogs for private repositories, but optional for public repositories. Note that GitHub only allows 50 unauthenticated requests per hour. By providing an API token, you allow this plugin to log in and thus remove the limit, which makes it useful for public repositories too. If you don't have one yet, you may generate a personal token for your repo. You don't need to tick any permissions for the plugin to work on public repositories, but you need the repo permission if you want to generate changelog for private repositories ("full access to private repo").

• githubRepository: the repository from which to get the issues to generate the change log.

• title: the title of the change log

• showUnreleased: if true, issues that were closed since the last tag will appear at the top of the change log. By default they will appear as "unreleased", unless a futureVersionTag is provided.

• unreleasedVersionTitle: the title for the unreleased issues at the top of the change log. Ignored if futureVersionTag is provided.

• futureVersionTag: if provided, and if showUnreleased is true, the unreleased issues will appear at the top of the change log under the provided tag. This allows to consider unreleased issues as part of an actual tag prior to actually creating the tag.

• sections: custom sections to classify the issues within each release. The section definitions are used to build a label-to-section mapping. The custom sections should be provided as a list of SectionDefinitions, with a title and one or more associated issue labels. Issues are placed into a section according to the first of their labels that is associated to a section. The provided custom sections are appended to the default sections (they don't replace them). However, if a custom section is associated to a label that is usually handled by a default section, the custom section takes precedence. In fact, the last section defining a mapping for a given issue label wins, and default sections are listed first.

• defaultIssueSectionTitle: section title for issues that are not classified in a specific section due to their labels

• defaultIssueSectionOrder: section order for issues that are not classified in a specific section due to their labels

• defaultPrSectionTitle: section title for pull-requests that are not classified in a specific section due to their labels

• defaultPrSectionOrder: section order for pull-requests that are not classified in a specific section due to their labels

• includeLabels: if not empty, only issues that have at least one of these labels can appear in the change log.

• excludeLabels: issues that have at least one of these labels will not appear in the change log, even if they have labels that are present in includeLabels.

• sinceTag: if provided, all prior tags will be excluded from the change log.

• skipTags: some specific tags to exclude from the change log. The issues that are part of the excluded tags are also excluded from the change log. They are not reported under the next tag.

• skipTagsRegex: tags matching one of these regexes are excluded from the change log.. The issues that are part of the excluded tags are also excluded from the change log. They are not reported under the next tag.

• releaseUrlTemplate: custom template for the URL of releases to use in the hyperlink on the title. If present, a %s placeholder will be replaced by the tag of the release. By default, it points to the source code of the git repository at the given tag.

• diffUrlTemplate: custom template for the URL to the full diff of the release. If present, 2 %s placeholders are replaced by the tag of the previous release and the current release, respectively. If you need to reverse the order, you may use %1$s for the "from" (previous) tag, and %2$s for the "to" (current) tag.

• releaseUrlTagTransform: a function to transform the tag string before injection in the releaseUrlTemplate. By default, this is the identity function and doesn't change the tag. It may be handy to remove or add a "v" prefix for instance.

• diffUrlTagTransform: a function to transform the tag strings before injection in the diffUrlTemplate. By default, this is the identity function and doesn't change the tags. It may be handy to remove or add a "v" prefix for instance.

• customTagByIssueNumber: a mapping from issue numbers to tags. An issue may be incorrectly classified due to late closing date or other timing problems. If this is the case, use this map to override the tag to use for a particular issue.

• useMilestoneAsTag: if true, issues associated to a milestone with a title that matches a tag will be associated to that tag, regardless of their close date.

• timezone: the timezone used to convert the tags timestamps to local dates for releases (defaults to GMT).

• outputFile: the file to write the change log to.

• latestReleaseBodyFile: the desired output path to a markdown file containing the release notes for the latest release. This is useful when generating GitHub releases with an embedded changelog. By default, the path is $buildDir/reports/changelog/latest-release-body.md