Conventional Commits

To create a useful revision history, teams should first agree on a commit message convention to use. This also applies to personal projects.

commit messages

Introduction to version control with Git

Version control software is an essential part of modern-day software developer practices.

By far, Git is the most widely used version control system in the world. It is a distributed and actively maintained open source project originally developed in 2005 by Linus Torvalds, the famous creator of the Linux operating system kernel.

What is a commit message?

The commit command is used to save changes to a local repository after staging in Git. However, before you can save changes in Git, you have to tell Git which changes you want to save as you might have made tons of edits. A great way to do that is by adding a commit message to identify your changes.

Commit Options

• -m

This option sets the commit’s message.

git add static/admin/config.yml
git commit -m "Setup multiple roles for netlify-cms git gateway"

• -a or — all

This option automatically commits all (including new) tracked, modified or deleted files.

git commit -a -m "Add a new role for netlify-cms git gateway"

• — amend

This option rewrites the very last commit with any currently staged changes or a new commit message and should only be performed on commits that have not been pushed to a remote repository, yet.

git add .
git commit --amend -m "Update roles for netlify-cms git gateway"

Why should you write good commit messages?

You might say, “It’s just a personal project.” Yes, you work alone now, but what happens when you work with a team or contribute to open source?

A well-crafted Git commit message is the best way to communicate context about a change to other developers working on that project, and indeed, to your future self.

Have you ever tried running git log on one of your old projects to see the "weird" commit messages you have used since its inception? It can be hard to understand why you made some changes in the past, and you'll wish you read this article earlier :).

Commit messages can adequately communicate why a change was made, and understanding that makes development and collaboration more efficient.

How to write commit messages with Git

Before now, I only used git commit -m "Fix X to allow Y to use Z" on my personal projects with just a subject and no extra description. This is great for small and clear fixes like git commit -m "Fix typo in README.md, but in cases of more extensive changes, you would need to add some extra details.

How to write good commit messages

There are several conventions used by different teams and developers to write good commit messages. I’ll only outline some general rules and tips for writing commit messages–you have to decide what convention you want to follow. And if you work for a company or contribute to open source, you have to adapt to their convention :).

For consistency, you can use one convention for work and another for personal projects as you might change jobs sometime, and the convention might also change.

Looks great, right? Here’s how you can make yours great too:

1. Specify the type of commit:

• feat: The new feature you’re adding to a particular application
• fix: A bug fix
• style: Feature and updates related to styling
• refactor: Refactoring a specific section of the codebase
• test: Everything related to testing
• docs: Everything related to documentation
• chore: Regular code maintenance.[ You can also use emojis to represent commit types]

1. Separate the subject from the body with a blank line
2. Your commit message should not contain any whitespace errors
3. Remove unnecessary punctuation marks
4. Do not end the subject line with a period
5. Capitalize the subject line and each paragraph
6. Use the imperative mood in the subject line
7. Use the body to explain what changes you have made and why you made them.
8. Do not assume the reviewer understands what the original problem was, ensure you add it.
9. Do not think your code is self-explanatory
10. Follow the commit convention defined by your team

The commit contains the following structural elements, to communicate intent to the consumers of your library:

1. fix: a commit of the type fix patches a bug in your codebase (this correlates with PATCH in Semantic Versioning).
2. feat: a commit of the type feat introduces a new feature to the codebase (this correlates with MINOR in Semantic Versioning).
3. BREAKING CHANGE: a commit that has a footer BREAKING CHANGE:, or appends a ! after the type/scope, introduces a breaking API change (correlating with MAJOR in Semantic Versioning). A BREAKING CHANGE can be part of commits of any type.
4. types other than fix: and feat: are allowed, for example @commitlint/config-conventional (based on the Angular convention) recommends build:, chore:, ci:, docs:, style:, refactor:, perf:, test:, and others.
5. footers other than BREAKING CHANGE: <description> may be provided and follow a convention similar to git trailer format.

Additional types are not mandated by the Conventional Commits specification, and have no implicit effect in Semantic Versioning (unless they include a BREAKING CHANGE). A scope may be provided to a commit’s type, to provide additional contextual information and is contained within parenthesis, e.g., feat(parser): add ability to parse arrays.

Examples

Commit message with description and breaking change footer

feat: allow provided config object to extend other configs

BREAKING CHANGE: `extends` key in config file is now used for extending other config files

Commit message with ! to draw attention to breaking change

feat!: send an email to the customer when a product is shipped

Commit message with scope and ! to draw attention to breaking change

feat(api)!: send an email to the customer when a product is shipped

Commit message with both ! and BREAKING CHANGE footer

chore!: drop support for Node 6

BREAKING CHANGE: use JavaScript features not available in Node 6.

Commit message with no body

docs: correct spelling of CHANGELOG

Commit message with scope

feat(lang): add Polish language

Commit message with multi-paragraph body and multiple footers

fix: prevent racing of requests

Introduce a request id and a reference to latest request. Dismiss
incoming responses other than from latest request.
Remove timeouts which were used to mitigate the racing issue but are
obsolete now.
Reviewed-by: Z
Refs: #123

Specification

The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in this document are to be interpreted as described in RFC 2119.

1. Commits MUST be prefixed with a type, which consists of a noun, feat, fix, etc., followed by the OPTIONAL scope, OPTIONAL !, and REQUIRED terminal colon and space.
2. The type feat MUST be used when a commit adds a new feature to your application or library.
3. The type fix MUST be used when a commit represents a bug fix for your application.
4. A scope MAY be provided after a type. A scope MUST consist of a noun describing a section of the codebase surrounded by parenthesis, e.g., fix(parser):
5. A description MUST immediately follow the colon and space after the type/scope prefix. The description is a short summary of the code changes, e.g., fix: array parsing issue when multiple spaces were contained in string.
6. A longer commit body MAY be provided after the short description, providing additional contextual information about the code changes. The body MUST begin one blank line after the description.
7. A commit body is free-form and MAY consist of any number of newline separated paragraphs.
8. One or more footers MAY be provided one blank line after the body. Each footer MUST consist of a word token, followed by either a :<space> or <space># separator, followed by a string value (this is inspired by the git trailer convention).
9. A footer’s token MUST use - in place of whitespace characters, e.g., Acked-by (this helps differentiate the footer section from a multi-paragraph body). An exception is made for BREAKING CHANGE, which MAY also be used as a token.
10. A footer’s value MAY contain spaces and newlines, and parsing MUST terminate when the next valid footer token/separator pair is observed.
11. Breaking changes MUST be indicated in the type/scope prefix of a commit, or as an entry in the footer.
12. If included as a footer, a breaking change MUST consist of the uppercase text BREAKING CHANGE, followed by a colon, space, and description, e.g., BREAKING CHANGE: environment variables now take precedence over config files.
13. If included in the type/scope prefix, breaking changes MUST be indicated by a ! immediately before the :. If ! is used, BREAKING CHANGE: MAY be omitted from the footer section, and the commit description SHALL be used to describe the breaking change.
14. Types other than feat and fix MAY be used in your commit messages, e.g., docs: update ref docs.
15. The units of information that make up Conventional Commits MUST NOT be treated as case sensitive by implementors, with the exception of BREAKING CHANGE which MUST be uppercase.
16. BREAKING-CHANGE MUST be synonymous with BREAKING CHANGE, when used as a token in a footer.

Why Use Conventional Commits

• Automatically generating CHANGELOGs.
• Automatically determining a semantic version bump (based on the types of commits landed).
• Communicating the nature of changes to teammates, the public, and other stakeholders.
• Triggering build and publish processes.
• Making it easier for people to contribute to your projects, by allowing them to explore a more structured commit history.

Conclusion

The most important part of a commit message is that it should be clear and meaningful. In the long run, writing good commit messages shows how much of a collaborator you are. The benefits of writing good commit messages are not only limited to your team, but indeed expand to yourself and future contributors.