Releasing Flake8

There is not much that is hard to find about how Flake8 is released.

  • We use major releases (e.g., 2.0.0, 3.0.0, etc.) for big, potentially backwards incompatible, releases.
  • We use minor releases (e.g., 2.1.0, 2.2.0, 3.1.0, 3.2.0, etc.) for releases that contain features and dependency version changes.
  • We use patch releases (e.g., 2.1.1, 2.1.2, 3.0.1, 3.0.10, etc.) for releases that contain only bug fixes.

In this sense we follow semantic versioning. But we follow it as more of a set of guidelines. We’re also not perfect, so we may make mistakes, and that’s fine.

Major Releases

Major releases are often associated with backwards incompatibility. Flake8 hopes to avoid those, but will occasionally need them.

Historically, Flake8 has generated major releases for:

  • Unvendoring dependencies (2.0)
  • Large scale refactoring (2.0, 3.0)
  • Subtly breaking CLI changes (3.0)
  • Breaking changes to its plugin interface (3.0)

Major releases can also contain:

  • Bug fixes (which may have backwards incompatible solutions)
  • New features
  • Dependency changes

Minor Releases

Minor releases often have new features in them, which we define roughly as:

  • New command-line flags
  • New behaviour that does not break backwards compatibility
  • New errors detected by dependencies, e.g., by raising the upper limit on PyFlakes we introduce F405
  • Bug fixes

Patch Releases

Patch releases should only ever have bug fixes in them.

We do not update dependency constraints in patch releases. If you do not install Flake8 from PyPI, there is a chance that your packager is using different requirements. Some downstream redistributors have been known to force a new version of PyFlakes, pep8/PyCodestyle, or McCabe into place. Occasionally this will cause breakage when using Flake8. There is little we can do to help you in those cases.


To prepare a release, we create a file in docs/source/releases/ named: {{ release_number }}.rst (e.g., 3.0.0.rst). We note bug fixes, improvements, and dependency version changes as well as other items of note for users.

Before releasing, the following tox test environments must pass:

  • Python 2.7 (a.k.a., tox -e py27)
  • Python 3.4 (a.k.a., tox -e py34)
  • Python 3.5 (a.k.a., tox -e py35)
  • PyPy (a.k.a., tox -e pypy)
  • Linters (a.k.a., tox -e linters)

We tag the most recent commit that passes those items and contains our release notes.

Finally, we run tox -e release to build source distributions (e.g., flake8-3.0.0.tar.gz), universal wheels, and upload them to PyPI with Twine.