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Jonathan Bowman
Jonathan Bowman

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Using Flake8 and pyproject.toml with FlakeHell

More and more, I am using Python tools like Poetry and Black that use pyproject.toml as a central configuration file for packaging and tools. The finalized PEP 518 defined the specification for pyproject.toml, and many tools have adopted it.

Unfortunately, two tools I use frequently do not yet support configuration through pyproject.toml: Flake8 and Mypy.

Thus far, I have not found any option for Mypy other than setup.cfg or mypy.ini, but I have found a solution for Flake8.

Enter FlakeHell.

FlakeHell is a Flake8 wrapper. Configuration is handled in pyproject.toml and can enable/disable specific Flake8 plugins, ignore specific errors, and handle files differently.

Example configuration

Here is my current configuration in pyproject.toml:

exclude = ["README.rst", ""]
format = "colored"
max_line_length = 88
show_source = true
whitelist = "../../allowlist.txt"

flake8-bandit = ["+*", "-S322"]
flake8-bugbear = ["+*"]
flake8-builtins = ["+*"]
flake8-comprehensions = ["+*"]
flake8-darglint = ["+*"]
flake8-docstrings = ["+*"]
flake8-eradicate = ["+*"]
flake8-isort = ["+*"]
flake8-mutable = ["+*"]
flake8-pytest-style = ["+*"]
flake8-spellcheck = ["+*"]
mccabe = ["+*"]
pep8-naming = ["+*"]
pycodestyle = ["+*"]
pyflakes = ["+*"]
pylint = ["+*"]
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Configure plugins

The above demonstrates that configuration can be passed from FlakeHell to the relevant plugin, such as the whitelist variable, a part of flake8-spellcheck.

Ignore specific warnings

Also note that certain codes (such as Bandit's S322 warning about input() that is not relevant in Python 3) can be ignored by prefixing them with a - and adding them to the list.

Pretty output

FlakeHell can format the output in various ways, including colorizing, grouping, or JSON-formatting.

Drop-in replacement for flake8

Thankfully, there is flake8helled, a command that replaces flake8, making it easy to configure your editor to use FlakeHell in place of Flake8.

Useful commands

When using FlakeHell, I frequently use the following commands:

  • flakehell lint runs the linter, similar to the flake8 command
  • flakehell plugins lists all the plugins used, and their configuration status
  • flakehell missed shows any plugins that are in the configuration but not installed properly (such as with pip or poetry add -D)
  • flakehell code S322 (or any other code) shows the explanation for that specific warning code.

See FlakeHell's documentation for more direction and ideas.

Happy linting.

Discussion (1)

franciscokloganb profile image
Francisco Barros

Just wanted to leave a comment for future readers that mypy already supports pyproject.toml.

See here: