We have very precise rules over how our git commit messages can be formatted. This leads to more readable messages that are easy to follow when looking through the project history.
- Separate subject from body with a blank line
- Limit the subject line to 70 characters
- Capitalize the subject line
- Do not end the subject line with a period
- Use the imperative mood in the subject line
- Use the body to explain what and why vs. how
- Each commit should be a single, stable change
Merge vs Rebase
Sentry uses a rebase workflow. That means that every commit on its own should be a clear, functional, and stable change. This means then when you’re building a new feature, you should try to pare it down into functional steps, and when that’s not reasonable, the end patch should be a single commit. This is counter to having a Pull Request which may include “fix [unmerged] behavior”. Those commits should be squashed, and the final patch when landed should be rebased.
Remember: each commit should follow the commit message format and be stable (green build).
Rebase and Merge
The GitHub UI exposes a “Rebase and Merge” option, which, if your commits are already in following the commit guidelines, is a great way to bring your change into the codebase.
When you are squashing your branch, it’s important to make sure you update the commit message. If you’re using GitHub’s UI it will by default create a new commit message which is a combination of all commits and does not follow the commit guidelines.
If you’re working locally, it often can be useful to
--amend a commit, or utilize
rebase -i to reorder, squash, and reword your commits.
Commit Message Format
Each commit message consists of a header, a body, and an optional footer.
The header has a special format that includes a type, a scope and a subject:
<type>(<scope>): <subject> (<jira-id>) <BLANK LINE> <body> <BLANK LINE> <footer>
The header is mandatory and the scope of the header is optional. If you have a Jira issue to link to, add the jira-id the commit belongs to. This helps to connect changes back to Jira tickets.
Any line of the commit message should not be longer 100 characters! This allows the message to be easier to read on GitHub as well as in various git tools.
The footer should contain a closing reference to an issue as well as a relevant Sentry issue if any.
feat(stream): Add resolve in next release action Expose a new action labeled 'resolve in next release'. It uses the existing API behavior and sends the 'inNextRelease=true' payload. Fixes GH-1234
As well as:
fix(stream): Handle empty reference on resolve action Gracefully handle when a user has not selected any issues and tries to complete the resolve action in the UI. Fixes GH-1234 Fixes SENTRY-1234
If the commit reverts a previous commit, it should begin with
revert:, followed by the header of the reverted commit. In the body it should say:
This reverts commit <hash>., where the hash is the SHA of the commit being reverted.
Must be one of the following:
|build:||Changes that affect the build system or external dependencies (example scopes: webpack, python, npm)|
|ci:||Changes to our CI configuration files and scripts (example scopes: travis, zeus)|
|docs:||Documentation only changes|
|feat:||A new feature|
|fix:||A bug fix|
|perf:||A code change that improves performance|
|ref:||A code change that neither fixes a bug nor adds a feature (refactor)|
|style:||Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc)|
|test:||Adding missing tests or correcting existing tests|
|meta:||Some meta information in the repo changes (example scopes: owner files, editor config etc.)|
|license:||Changes to licenses|
The scope should be the name of the core component affected (as perceived by someone reading the changelog generated from commit messages). This means it should be the system impacted, not the literal file changed. For example, if the code primarily affects billing, you’d use the billing scope, even if the changes are in utility files or db schema.
The following is the list of suggested scopes:
It is also acceptable to use the feature/project name as a scope.
The subject contains a succinct description of the change:
- Use the imperative, present tense: “change” not “changed” nor “changes”
- Capitalize the first letter
- No dot (.) at the end
Just as in the subject, use the imperative, present tense: “change” not “changed” nor “changes”. The body should include the motivation for the change and contrast this with previous behavior.
The footer should contain any information about Breaking Changes and is also the place to reference GitHub issues that this commit Closes.
Breaking Changes should start with the word
BREAKING CHANGE: with a space or two newlines. The rest of the commit message is then used for this.