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As discussed in a recent [PR][1], people should treat their changelogs as canonical sources given their portability. Release posts can easily be created manually or automatically since the Keep a Changelog format is easy to parse for both humans and machines. [1]: https://github.com/olivierlacan/keep-a-changelog/pull/629#issuecomment-2766514005
380 lines
14 KiB
Plaintext
380 lines
14 KiB
Plaintext
---
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title: Keep a Changelog
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description: Don’t let your friends dump git logs into changelogs.
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language: en
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version: 1.1.0
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---
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.header
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.title
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%h1= current_page.data.title
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%h2= current_page.data.description
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= link_to data.links.changelog do
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Version
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%strong= current_page.metadata[:page][:version]
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%pre.changelog{ lang: "en" }= File.read("CHANGELOG.md")
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.answers
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%h3#what
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%a.anchor{ href: "#what", aria_hidden: "true" }
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What is a changelog?
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%p.updated
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A changelog is a document which contains a curated, chronologically
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ordered list of notable changes for each version of a project.
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%h3#why
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%a.anchor{ href: "#why", aria_hidden: "true" }
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Why keep a changelog?
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%p.updated
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To make it easier for users and contributors to see precisely what
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notable changes have been made between each iteration of the project.
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%h3#who
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%a.anchor{ href: "#who", aria_hidden: "true" }
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Who needs a changelog?
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%p
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People do. Whether consumers or developers, the end users of
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software are human beings who care about what's in the software. When
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the software changes, people want to know why and how.
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.good-practices
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%h3#how
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%a.anchor{ href: "#how", aria_hidden: "true" }
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How do I make a good changelog?
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%h4#principles
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%a.anchor{ href: "#principles", aria_hidden: "true" }
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Guiding Principles
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%ul
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%li
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Changelogs are <em>for humans</em>, not machines.
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%li.updated
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Every single version should have an entry.
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%li.updated
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Changes of the same type should be grouped.
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%li.updated
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Direct links to versions and sections should exist.
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%li.updated
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The first version listed should be the latest.
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%li.updated
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Release dates should be listed for each version.
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%li.updated
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Use of #{link_to "versioning schemes", data.links.schemes} should be noted.
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%a.anchor{ href: "#types", aria_hidden: "true" }
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%h4#types Types of changes
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%ul
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%li
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%code Added
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for new features.
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%li
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%code Changed
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for changes in existing functionality.
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%li
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%code Deprecated
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for soon-to-be removed features.
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%li
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%code Removed
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for now removed features.
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%li
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%code Fixed
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for any bug fixes.
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%li
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%code Security
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in case of vulnerabilities.
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.effort
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%h3#effort
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%a.anchor{ href: "#effort", aria_hidden: "true" }
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How can I reduce the effort required to maintain a changelog?
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%p.updated
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First, start by keeping an <code>Unreleased</code> section at the top of your
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changelog to track upcoming changes.
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%p This serves two purposes:
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%ul
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%li
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People can see what changes they might expect in upcoming releases
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%li
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At release time, you can move the <code>Unreleased</code> section
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changes into a new release version section.
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%p.new
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Second, consider that communicating about project changes is a critical
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aspect of maintaining it. Maybe it isn't your preferred focus, but
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contributors and users hugely benefit from changelogs.
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%p.new
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There are many ways you can reduce the maintenance friction of a changelog,
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but be careful about accidentally making your project tedious to maintain
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*because* of your changelog.
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%p.new
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%strong
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Making changes and communicating about changes are two fundamentally
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different things.
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%p.new
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"Don’t let your friends dump git logs into changelogs." doesn't mean "let
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your enemies turn your changelogs into git commits". The curation process
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involved in synthesizing <em>notable</em> changes inherently implies that
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there are non-notable changes to a project which don't belong in a changelog.
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Attempting to categorize these changes when they are being made is not only
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counter-productive, it's an exercise in tedium I wouldn't wish on anyone.
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.bad-practices
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%h3#bad-practices
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%a.anchor{ href: "#bad-practices", aria_hidden: "true" }
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Can changelogs be bad?
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%p Yes. Here are a few ways they can be less than useful.
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%h4#log-diffs
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%a.anchor{ href: "#log-diffs", aria_hidden: "true" }
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Commit log diffs
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%p
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Using commit log diffs as changelogs is a bad idea: they're full of
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noise. Things like merge commits, commits with obscure titles,
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documentation changes, etc.
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%p
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The purpose of a commit is to document a step in the evolution of
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the source code. Some projects clean up commits, some don't.
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%p
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The purpose of a changelog entry is to document the noteworthy
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difference, often across multiple commits, to communicate them
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clearly to end users.
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%h4#ignoring-deprecations
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%a.anchor{ href: "#ignoring-deprecations", aria_hidden: "true" }
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Ignoring Deprecations
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%p
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When people upgrade from one version to another, it should be
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painfully clear when something will break. It should be possible to
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upgrade to a version that lists deprecations, remove what's
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deprecated, then upgrade to the version where the deprecations
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become removals.
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%p
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If you do nothing else, list deprecations, removals, and any
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breaking changes in your changelog.
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%h4#confusing-dates
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%a.anchor{ href: "#confusing-dates", aria_hidden: "true" }
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Confusing Dates
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%p
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Regional date formats vary throughout the world and it's often
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difficult to find a human-friendly date format that feels intuitive
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to everyone. The advantage of dates formatted like
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<code>2017-07-17</code> is that they follow the order of largest to
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smallest units: year, month, and day. This format also doesn't
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overlap in ambiguous ways with other date formats, unlike some
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regional formats that switch the position of month and day numbers.
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These reasons, and the fact this date format is an
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#{link_to "ISO standard", data.links.isodate}, are why it is the recommended date
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format for changelog entries.
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%h4#inconsistent-changes
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%a.anchor{ href: "#inconsistent-changes", aria_hidden: "true" }
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Inconsistent Changes
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%p.updated
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A changelog which only mentions some of the changes can be as dangerous
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as not having a changelog at all.
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%p.updated
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While many of the changes may not be relevant - for instance, removing a single whitespace may not need
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to be recorded in all instances - any important changes should be
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mentioned in the changelog. By inconsistently applying changes,
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your users may mistakenly think that the changelog is the single source
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of truth. It ought to be. With great power comes great responsibility -
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having a good changelog means having a consistently updated changelog.
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%aside
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There’s more. Help me collect these antipatterns by
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= link_to "opening an issue", data.links.issue
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or a pull request.
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.frequently-asked-questions
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%h3#frequently-asked-questions
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%a.anchor{ href: "#frequently-asked-questions", aria_hidden: "true" }
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Frequently Asked Questions
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%h4#standard
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%a.anchor{ href: "#standard", aria_hidden: "true" }
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Is there a standard changelog format?
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%p.updated
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When this project first started, there were of course the
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#{link_to "GNU changelog style guide", data.links.gnustyle},
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or the #{link_to "two-paragraph-long GNU NEWS file", data.links.gnunews}
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"guideline". But those were in many ways insufficient. Keep a Changelog
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doesn't aim to be the one true standard for changelogs, but it does aim to
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show how useful thoughtful communication about iterative changes can be.
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%p.updated
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This project aims to be a
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#{link_to "better changelog convention", data.links.changelog}. It started
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based on observation of good practices in the open source software community
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but it can be useful to any project which sees frequent changes, particularly
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changes that require outward-facing communication.
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%p.updated
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Open #{link_to "discussions", data.links.discussions} and
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#{link_to "suggestions for improvements", data.links.issue} are welcome.
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%h4#filename
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%a.anchor{ href: "#filename", aria_hidden: "true" }
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What should the changelog file be named?
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%p
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Call it <code>CHANGELOG.md</code>. Some projects use
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<code>HISTORY</code>, <code>NEWS</code> or <code>RELEASES</code>.
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%p
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While it's easy to think that the name of your changelog file
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doesn't matter that much, why make it harder for your end users to
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consistently find notable changes?
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%p.new
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Some may argue that a `CHANGELOG` file should... log all changes that
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occured. This is absurd on its face given all modern version control tools
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and code hosting platforms offer this output without the need for a static
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export. Rather than be pedantic about the common usage of the word
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"changelog", it seems more fruitful to work toward improving them.
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%h4#releases
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%a.anchor{ href: "#releases", aria_hidden: "true" }
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What about Releases?
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%p.updated
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Code hosting platform offer ways to publish release posts. Nowadays
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many projects communicate about version releases using these posts. Posts
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can be created from with version-specific git tags.
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%p.updated
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The value of these release posts is limited. They often encourage
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maintainers to create information about project changes that is not portable
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across code hosting platforms. When release notes are published exclusively
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in these posts, they're not kept in version history unlike like a changelog
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text file stored in the repository.
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%p.update
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It's best to focus on changelog text files first and either derive these
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individual release posts manually or use tools to create release posts
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when a new version is added to the changelog.
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%h4#automatic
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%a.anchor{ href: "#automatic", aria_hidden: "true" }
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Can changelogs be automatically parsed?
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%p.updated
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It’s difficult, because people follow wildly different formats and
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file names. But if a project follows a consistent format (like the one
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recommended here) it can be very useful.
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%p.new
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For example, it's rare to see people immediately upgrade as soon as a new
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version is released. By the time they're able to, there may be multiple
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versions to consider.
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%p.new
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An automatically parsed changelog can help people see a filtered list of
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changes between specific versions, making their upgrade process much easier.
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%h4#yanked
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%a.anchor{ href: "#yanked", aria_hidden: "true" }
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What about yanked releases?
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%p
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Yanked releases are versions that had to be pulled because of a
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serious bug or security issue. Often these versions don't even
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appear in change logs. They should. This is how you should display
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them:
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%p <code>## [0.0.5] - 2014-12-13 [YANKED]</code>
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%p
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The <code>[YANKED]</code> tag is loud for a reason. It's important
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for people to notice it. Since it's surrounded by brackets it's also
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easier to parse programmatically.
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%h4#rewrite
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%a.anchor{ href: "#rewrite", aria_hidden: "true" }
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Should you ever rewrite a changelog?
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%p.updated
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There can be good reasons to improve a changelog after a version has been
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released. For example some projects may forget to add a changelog entry for
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a version, which would have to be retroactively addede to the changelog.
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%p.updated
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It's also possible maintainers may discover they forgot address a
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breaking change in the notes for a released version. Updating the changelog
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would be sensible in these cases. However it might be a good idea to denote
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the date at which the changelog was updated for a given version. This may
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help people reading the changelog notice the change.
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%h4#contribute
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%a.anchor{ href: "#contribute", aria_hidden: "true" }
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How can I contribute?
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%p.updated
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This project doesn't claim to be the only way to communicate about changes.
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It's merely a carefully considered opinion, with context and hopefully useful
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examples. It has helped hundreds of thousands of projects improve their
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release communication process, but it's just as much of a work in progress.
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%p.updated
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In the decade since Keep a Changelog was release itself, release communication
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has improved dramatically, at least in the open source world. This project
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played a small part but each evolution was the result of discussion and
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input from the community.
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%p.updated
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So please #{link_to "contribute", data.links.repo} to Keep a Changelog or
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start a #{link_to "conversation", data.links.discussions} if you need more help.
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%h4#git.new
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%a.anchor{ href: "#git", aria_hidden: "true" }
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What's a "git log"?
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%p.new
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A git log is a command used by the #{link_to "git", data.links.git}
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distributed {link_to "version control system", data.links.dvsc} to display
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all changes recorded in a given source code repository.
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%p.new
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Git is a tool used by a large and growing share of software projects around
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the world. Keep a Changelog is mainly focused on communication about
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software evolution which is why our tag line references "git log" in an
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slightly caustic way. This is because open source maintainers have long had
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the problematic habit to convert "git log" command output into release notes
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for their projects, with little regard for the actual human beings who had
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to try and digest these so-called "changelogs" made up for hundreds of
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individual changes, often written hastily.
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.press
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%h3 Conversations
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%p
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I went on #{link_to "The Changelog podcast", data.links.thechangelog}
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to talk about why maintainers and contributors should care about changelogs,
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and also about the motivations behind this project.
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