The Flake8 Python linter (

Backend: pants.backend.python.lint.flake8
Config section: [flake8]

Basic options




default: False

Don't use Flake8 when running ./pants lint.


--flake8-args="[<shell_str>, <shell_str>, ...]"


default: []

Arguments to pass directly to Flake8, e.g. --flake8-args='--ignore E123,W456 --enable-extensions H111'.




default: True

If true, export a virtual environment with Flake8 when running ./pants export.

This can be useful, for example, with IDE integrations to point your editor to the tool's binary.

Advanced options




default: flake8>=3.9.2,<4.0

Requirement string for the tool.


--flake8-extra-requirements="['<str>', '<str>', ...]"


default: []

Any additional requirement strings to use with the tool. This is useful if the tool allows you to install plugins or if you need to constrain a dependency to a certain version.




default: <default>

Path to a lockfile used for installing the tool.

Set to the string <default> to use a lockfile provided by Pants, so long as you have not changed the --version and --extra-requirements options, and the tool's interpreter constraints are compatible with the default. Pants will error or warn if the lockfile is not compatible (controlled by [python].invalid_lockfile_behavior). See for the default lockfile contents.

Set to the string <none> to opt out of using a lockfile. We do not recommend this, though, as lockfiles are essential for reproducible builds.

To use a custom lockfile, set this option to a file path relative to the build root, then run ./pants generate-lockfiles --resolve=flake8.

As explained at Third-party dependencies, lockfile generation via generate-lockfiles does not always work and you may want to manually generate the lockfile. You will want to set [python].invalid_lockfile_behavior = 'ignore' so that Pants does not complain about missing lockfile headers.




default: flake8

The console script for the tool. Using this option is generally preferable to (and mutually exclusive with) specifying an --entry-point since console script names have a higher expectation of staying stable across releases of the tool. Usually, you will not want to change this from the default.




default: None

The entry point for the tool. Generally you only want to use this option if the tool does not offer a --console-script (which this option is mutually exclusive with). Usually, you will not want to change this from the default.




default: None

Path to an INI config file understood by Flake8 (

Setting this option will disable [flake8].config_discovery. Use this option if the config is located in a non-standard location.




default: True

If true, Pants will include any relevant config files during runs (.flake8, flake8, setup.cfg, and tox.ini).

Use [flake8].config instead if your config is in a non-standard location.


--flake8-source-plugins="[<target_option>, <target_option>, ...]"


default: []

An optional list of python_sources target addresses to load first-party plugins.

You must set the plugin's parent directory as a source root. For example, if your plugin is at build-support/flake8/, add 'build-support/flake8' to [source].root_patterns in pants.toml. This is necessary for Pants to know how to tell Flake8 to discover your plugin. See Source roots

You must also set [flake8:local-plugins] in your Flake8 config file.

For example:

    extension =
        CUSTOMCODE = custom_plugin:MyChecker

While your plugin's code can depend on other first-party code and third-party requirements, all first-party dependencies of the plugin must live in the same directory or a subdirectory.

To instead load third-party plugins, set the option [flake8].extra_requirements.

Tip: it's often helpful to define a dedicated 'resolve' via [python].resolves for your Flake8 plugins such as 'flake8-plugins' so that the third-party requirements used by your plugin, like flake8, do not mix with the rest of your project. Read that option's help message for more info on resolves.

Deprecated options


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