Contribution Guidelines

Getting Started

So you want to contribute? Great! Here’s a short checklist with the most important points:

  • Don’t worry. You are not expected to get everything right on the first attempt, we’ll guide you through it.

  • Make sure there is an issue that describes the change you want to do. If the thing you want to do does not have an issue yet, please file one before starting work on it.

  • Fork the repository and make your changes in a new branch. If you already have push access to the Syncthing repository, do not create a new branch there. We do all changes as pull requests from personal forks.

Authorship

All code authors are listed in the AUTHORS file. When your first pull request is accepted, the maintainer will add your details to the AUTHORS file, the NICKS file and the list of authors in the GUI. Commits must be made with the same name and email as listed in the AUTHORS file. To accomplish this, ensure that your git configuration is set correctly prior to making your first commit:

$ git config --global user.name "Jane Doe"
$ git config --global user.email janedoe@example.com

You must be reachable on the given email address. If you do not wish to use your real name for whatever reason, using a nickname or pseudonym is perfectly acceptable.

Team Membership

Contributing useful commits via pull requests will at some point get you invited to the Syncthing core team. This team gives you push access to most repositories, subject to the guidelines below.

The Syncthing maintainers team has the same access permissions, the added responsibility of reviewing major changes, and the ability to invite members into the core team.

Code Review

Commits will generally fall into one of the three categories below, with different requirements on review.

Trivial:

A small change or refactor that is obviously correct. These may be pushed without review by any member of the core team. Examples: removing dead code, updating values.

Minor:

A new feature, bugfix or refactoring that may need extra eyes on it to weed out mistakes, but is architecturally simple or at least uncontroversial. Minor changes must go through a pull request and can be merged on approval by any other developer on the core or maintainers team. Tests must pass. Examples: adding caching, fixing a small bug.

Major:

A complex new feature or bugfix, a large refactoring, or a change to the underlying architecture of things. A major change must be reviewed by a member of the maintainers team. Tests must pass.

The categorization is inherently subjective; we recommend erring on the side of caution - if you are not sure whether a change is trivial or merely minor, it’s probably minor.

First time contributions from new developers are always major.

Coding Style

General

  • All text files use Unix line endings. The git settings already present in the repository attempts to enforce this.

  • When making changes, follow the brace and parenthesis style of the surrounding code.

Go Specific

  • Follow the conventions laid out in Effective Go as much as makes sense. The review guidelines in Go Code Review Comments should generally be followed.

  • Each commit should be go fmt clean.

  • Imports are grouped per goimports standard; that is, standard library first, then third party libraries after a blank line.

Commits

  • The commit message subject should be a single short sentence describing the change, starting with a capital letter but without ending punctuation, and prefixed with the package name most affected by the change.

  • Commits that resolve an existing issue must include the issue number as (fixes #123) at the end of the commit message subject. A correctly formatted commit message looks like this:

    lib/dialer: Add env var to disable proxy fallback (fixes #3006)

  • If the commit message subject doesn’t say it all, one or more paragraphs of describing text should be added to the commit message. This should explain why the change is made and what it accomplishes.

  • When drafting a pull request, please feel free to add commits with corrections and merge from main when necessary. This provides a clear time line with changes and simplifies review. Do not, in general, rebase your commits.

  • Pull requests are merged to main using squash merge. The “stream of consciousness” set of commits described in the previous point will be reduced to a single commit at merge time.

Tests

Yes please, do add tests when adding features or fixing bugs. Also, when a pull request is filed a number of automatic tests are run on the code. This includes:

  • That the code actually builds and the test suite passes.

  • That the code is correctly formatted (go fmt).

  • That the commits are based on a reasonably recent main.

  • That the author is listed in AUTHORS.

  • That the output from go lint and go vet is clean. (This checks for a number of potential problems the compiler doesn’t catch.)

If the pull request is invasive or scary looking, the full integration test suite can be run as well.

Branches

  • main is the main branch containing good code that will end up in the next release. You should base your work on it. It won’t ever be rebased or force-pushed to.

  • vx.y branches exist to make patch releases on otherwise obsolete minor releases. Should only contain fixes cherry picked from main. Don’t base any work on them.

  • Other branches are probably topic branches and may be subject to rebasing. Don’t base any work on them unless you specifically know otherwise.

Tags

All releases are tagged semver style as vx.y.z. The maintainer doing the release signs the tag using their GPG key.

Licensing

All contributions are made under the same MPLv2 license as the rest of the project, except documentation, user interface text and translation strings which are licensed under the Creative Commons Attribution 4.0 International License. You retain the copyright to code you have written.