The Flake8 Python linter (https://flake8.pycqa.org/).

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

Basic options




default: False

If true, 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'.

Advanced options




default: None

If specified, install the tool using the lockfile for this named resolve.

This resolve must be defined in [python].resolves, as described in Third-party dependencies.

The resolve's entire lockfile will be installed, unless specific requirements are listed via the requirements option, in which case only those requirements will be installed. This is useful if you don't want to invalidate the tool's outputs when the resolve incurs changes to unrelated requirements.

If unspecified, and the lockfile option is unset, the tool will be installed using the default lockfile shipped with Pants.

If unspecified, and the lockfile option is set, the tool will use the custom flake8 "tool lockfile" generated from the version and extra_requirements options. But note that this mechanism is deprecated.


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


default: []

If install_from_resolve is specified, install these requirements, at the versions provided by the specified resolve's lockfile.

Values can be pip-style requirements (e.g., tool or tool==1.2.3 or tool>=1.2.3), or addresses of python_requirement targets (or targets that generate or depend on python_requirement targets).

The lockfile will be validated against the requirements - if a lockfile doesn't provide the requirement (at a suitable version, if the requirement specifies version constraints) Pants will error.

If unspecified, install the entire lockfile.




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 (https://flake8.pycqa.org/en/latest/user/configuration.html).

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


--flake8-extra-files="[<file_option>, <file_option>, ...]"


default: []

Paths to extra files to include in the sandbox. This can be useful for Flake8 plugins,
like including config files for the flake8-bandit plugin.




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/custom_plugin.py, 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




default: flake8>=5.0.4,<7

Deprecated, is scheduled to be removed in version: 2.18.0.dev1.
Custom tool versions are now installed from named resolves, as described at [Lockfiles](doc:python-lockfiles).

Requirement string for the tool.


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


default: []

Deprecated, is scheduled to be removed in version: 2.18.0.dev1.
Custom tool versions are now installed from named resolves, as described at [Lockfiles](doc:python-lockfiles).

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>

Deprecated, is scheduled to be removed in version: 2.18.0.dev0.
Custom tool versions are now installed from named resolves, as described at [Lockfiles](doc:python-lockfiles).

  1. If you have an existing resolve that includes the requirements for this tool,
    you can set `[flake8].install_from_resolve = "<resolve name>".
    This may be the case if the tool also provides a runtime library, and you want
    to specify the version in just one place.
  2. If not, you can set up a new resolve as described at the link above.

Either way, the resolve you choose should provide the requirements currently set by the version and extra-requirements options for this tool, which you can see by running pants help-advanced flake8.

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 https://github.com/pantsbuild/pants/blob/release_2.17.0rc4/src/python/pants/backend/python/lint/flake8/flake8.lock for the default lockfile contents.

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

Alternatively, you can set this option to the path to a custom lockfile using pip's requirements.txt-style, ideally with --hash. Set [python].invalid_lockfile_behavior = 'ignore' so that Pants does not complain about missing lockfile headers.




default: True

Deprecated, is scheduled to be removed in version: 2.18.0.dev0.
Use the export goal's --resolve option to select tools to export, instead of using this option to exempt a tool from export-by-default.

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.