pre-commit not using virtual environment

Question

I added this to pre-commit-config.yml

-   repo: local
    hooks:
    -   id: python-hook
        name: python-hook
        entry: python python_script.py
        language: python
        pass_filenames: false

Where python_script.py has the following content

#!/usr/bin/env python

import os

print(os.environ["VIRTUAL_ENV"])

import requests

The package requests is installed inside the active virtual environment, when I run pre-commit I get this output

/path/to/home/.cache/pre-commit/repouecs3sp4/py_env-python3.7
Traceback (most recent call last):
  File "python_script.py", line 7, in <module>
    import requests
ModuleNotFoundError: No module named 'requests'

The issue here is that the path to the virtual environment is apparently switched to a different one /path/to/home/.cache/pre-commit/repouecs3sp4/py_env-python3.7.

Is there something I'm missing here? Thanks for your help

Paucker

Answer 1

kind of the point of pre-commit is it installs tools in isolated environments so they don't interfere with whatever state your current development environment is in -- language: python tells pre-commit to create its own python virtualenv

if you don't want that you can use language: system -- but this is the unsupported escape hatch for when you don't want managed tools (and note that pre-commit won't provision those environments for your contributors so they will need to make sure they have the particular environment set up and activated)

the better way is to declare the dependencies your local hook needs to pre-commit such that it can provision an environment for you using additional_dependencies -- for example if you needed packaging in your tool:

repos:
-   repo: local
    hooks:
    -   id: python-hook
        name: python-hook
        entry: python python_script.py
        language: python
        pass_filenames: false
        additional_dependencies: [packaging]

note again that pre-commit does not install from the repository under test (if it did, caching would be difficult-to-intractable) so you cannot use things like -r requirements.txt in additional_dependencies)

---

disclaimer: I created pre-commit

Claim

I'm trying to have pre-commit check if my Python project's requirements.txt matches pip freeze (for my current venv) - is there a way to force it to use whatever venv the committer is currently using? – Erased

So am I just meant to duplicate everything from pyproject.toml into .pre-commit-config.yaml? – Kidnap

langauge: system dude saved life – Apocarpous