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captainhook 0.8.5

A collection of git commit hooks

Latest Version: 0.8.6

Git hook scripts

What is it

A set of configurable git hooks and checks.

Upon committing code, the pre-commit hook runs configured checks against the files to be committed and rejects the commit if any of the checks turned on fail.


Install using pip:

pip install captainhook

You can then install the hooks using:

captainhook install

from within any git repo, and the pre-commit hook will be installed.

Running without commiting

You can perform a run against all your code base using:

captainhook run

Setting Up

To turn a check on or off, create a tox.ini file in the base directory of your project with a captainhook section.



flake8, pdb and python3 checks default to being on.

Checks can also be passed arguments from the config file. This is done with the following notation:

<check_name>=<status>;<string to be passed through>

Currently checks can only be passed a single argument and must do the parsing of that themselves.

flake8 obeys the configuration as per the flake8 docs but any path-related options will need to use wildcard patterns (e.g. exclude=*/migrations/* instead of exclude=migrations).

To avoid being checked at all, you can commit using the --no-verify flag:

git commit -a --no-verify


Currently supported checks are

  • pdb: Checks to see if there are any uncommented import pdb; pdb.set_trace() statements in the code to be committed.
  • flake8: Runs flake8 against the files that are set to be committed.
  • python3: Checks to see if python files set to be committed are python3 compatible.
  • isort: Checks to see if all import statements have been sorted correctly.
  • grep: Runs the given grep command against the files in your commit.
    • Takes a single argument; options which will be passed through to grep verbatim.
    • Currently you can only specify a single grep command.
  • block_branch: Checks if the current branch is in a list of branches that should not be committed to.
  • merge_marks: Checks if there are any signs of unresolved merge marks in the files to be committed.


You only see output for checks that fail, otherwise silence.

Example output upon a rejected commit:

Checking python3
--- captainhook/   (original)
+++ captainhook/   (refactored)
@@ -66,7 +66,7 @@
     "Check there are changes to stash"
     return bool(bash('git diff'))

-print 'a'
Checking flake8
=============================================================================== F401 'importlib' imported but unused E302 expected 2 blank lines, found 1 E501 line too long (89 > 79 characters)
Rejecting commit


You can add your own check to your git env quite easily.

Simply add a module to .git/hooks/checkers with a run() method defined.

The method should return the error string on faillure, or a False like object on success.

For example:

$ cat .git/hooks/checkers/
DEFAULT = 'on'
def run():
    return "NOT A CHANCE"

This will block all commits if enabled.

A checker can set the following variables:

DEFAULT: used to determine the check is assumed “on” or “off”. This value is only used if tox.ini has not been used to override it. The default DEFAULT is off.

CHECK_NAME: To override the display name of the module.

REQUIRED_FILES: Files that, if present, should be included in the copy to the temp directoy before analysis takes place.


I’m interested in hearing feedback - positive or negative - about this.

Please make yourself at home, create issues if you’ve got problems with existing behaviour, or suggestions for future improvements or anything else.

You can reach me on twitter @couperalex.


Running on its own will by default create copies of the files to be committed which you probably don’t want when testing a new check.

You can run the script against all your code base using:

python captainhook/ --all
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