# Ruff

[Ruff](https://github.com/charliermarsh/ruff) is an extremely fast Python
linter and formatter, written in Rust. It can process all of mozilla-central in
under a second, and implements rule sets from a large array of Python linters
and formatters, including:

- flake8 (pycodestyle, pyflakes and mccabe)
- isort
- pylint
- pyupgrade
- and many many more!

## Run Locally

The mozlint integration of ruff can be run using mach:

```{eval-rst}
.. parsed-literal::

   $ mach lint --linter ruff <file paths>

```

## Configuration

Ruff is configured in the root {searchfox}`pyproject.toml` file. Additionally, ruff will
pick up any `pyproject.toml` or `ruff.toml` files in subdirectories. The
settings in these files will only apply to files contained within these
subdirs. For more details on configuration discovery, see the [configuration
documentation][configuration documentation].

For a list of options, see the [settings documentation].

## Sources

- {searchfox}`Configuration (YAML) <tools/lint/ruff.yml>`
- {searchfox}`Source <tools/lint/python/ruff.py>`

[configuration documentation]: https://beta.ruff.rs/docs/configuration/
[settings documentation]: https://beta.ruff.rs/docs/settings/