FlakeHeaven can be configured in pyproject.toml. You can specify any Flake8 options and FlakeHeaven-specific parameters. Also,

Config resolving order (every next step overwrites previous one):

  1. Flake8 legacy configs: setup.cfg, tox.ini, .flake8. Everything you’ve specified for Flake8 will work for FlakeHeaven. The only exception is list of checks, it must be explicitly specified in FlakeHeaven’s config via plugins. By default, FlakeHeaven runs only pyflakes and pycodestyle.

  2. Modern and beautiful FlakeHeaven’s config in pyproject.toml. Here you can configure everything for FlakeHeaven. Use it.

  3. CLI options.


In pyproject.toml you can specify [tool.flakeheaven.plugins] table. It’s a list of flake8 plugins and associated to them rules.

Key can be exact plugin name or wildcard template. For example "flake8-commas" or "flake8-*". FlakeHeaven will choose the longest match for every plugin if possible. In the previous example, flake8-commas will match to the first pattern, flake8-bandit and flake8-bugbear to the second, and pycodestyle will not match to any pattern.

Value is a list of templates for error codes for this plugin. First symbol in every template must be + (include) or - (exclude). The latest matched pattern wins. For example, ["+*", "-F*", "-E30?", "-E401"] means “Include everything except all checks that starts with F, check from E301 to E310, and E401”.


Use exceptions section to specify special rules for particular paths:

pycodestyle = ["+*"]
pyflakes = ["+*"]

# match by prefix
pycodestyle = ["-F401"]     # disable a check
pyflakes = ["-*"]           # disable a plugin

pyflakes = ["+*"]           # enable a plugin

# match by glob
pyflakes = ["-*"]

path can be either a path prefix (from the project root) or a glob pattern.

If a file matches multiple patterns, the best pattern is chosen, following the nginx-style:

  1. Prefix-pattern always beats glob-pattern

  2. Among all matching patterns of the same type, the most specific one (with the longest length) wins.

For example, in the file structure:

└─ dir_1
   └─ dir_1_1

Patterns will have the following priorities:

  1. root/dir_1/dir_1_1/ (most specific prefix-pattern)

  2. root/dir_1/ (less specific prefix-pattern, but still beats glob-patterns)

  3. root/dir_1/* (the longest glob beats the shorter one)

  4. root/* (the widest glob-pattern)


Option base allows to specify base config from which you want to inherit this one. It can be path to local config or remote URL. You can specify one path or list of paths as well. For example:

base = ["", ".flakeheaven.toml"]
max_line_length = 90

In this example, FlakeHeaven will read remote config, local config (.flakeheaven.toml), and then current config. So, even if max_line_length is specified in some of base configs, it will be overwritten by max_line_length = 90 from current config.


Most of default parameters are the same as in Flake8. However, some of them are different to make FlakeHeaven cool:

# make output beautiful
# 80 chars limit isn't enough in 21 century

Cache settings

FlakeHeaven caches results. Cache invalidates after 24 hours or if the configuration was changed. Default cache directory is .flakeheaven_cache in your working directory.

It can be changed by environment variable FLAKEHEAVEN_CACHE. Also, you can change threshold by variable FLAKEHEAVEN_CACHE_TIMEOUT.


Additional settings

FlakeHeaven provides a few additional options that aren’t supported by the original flake8. They can be specified as everything else, in config or as CLI flags.

  • --baseline – path to baseline file.

  • --relative – Treat file paths as relative to directory containing baseline file.

  • --safe – suppress exceptions from plugins. In that case, the exception will be converted into E902 error.

Ignored options

FlakeHeaven doesn’t support some flake8 option by design. Flake8 has a long history and over-complicated logic to enable and disable some checks. We make it simple.

  • --extend-exclude - use just exclude, modify it right in the config if you need.

  • --per-file-ignores - use exceptions.

  • --statistics - use --format=stat instead.

  • --ignore - use plugins.

  • --extend-ignore - use plugins.

  • --select - use plugins.

  • --enable-extensions - use plugins.


# optionally inherit from remote config (or local if you want)
base = ""
# specify any flake8 options. For example, exclude "":
exclude = [""]
# make output nice
format = "grouped"
# don't limit yourself
max_line_length = 120
# show line of source code in output
show_source = true

# list of plugins and rules for them
# include everything in pyflakes except F401
pyflakes = ["+*", "-F401"]
# enable only codes from S100 to S199
flake8-bandit = ["-*", "+S1??"]
# enable everything that starts from `flake8-`
"flake8-*" = ["+*"]
# explicitly disable plugin
flake8-docstrings = ["-*"]

# disable some checks for tests
pycodestyle = ["-F401"]     # disable a check
pyflakes = ["-*"]           # disable a plugin

# do not disable `pyflakes` for one file in tests
pyflakes = ["+*"]           # enable a plugin

See Flake8 documentation to read more about Flake8-specific configuration.