How does hatch locate python versions? Can it work with pyenv?

[gerbendekkervolue]

I am stumped trying to figure out how to make hatch work with pyenv. I think I do not understand how hatch tries to locate the available python versions.

https://hatch.pypa.io/latest/config/hatch/#python-installations talks about "where to install python versions". This phrasing suggests hatch is going to install python versions on my machine, is that correctly understood? Or this this mean that I could point in this config file to my local pyenv folder and all would be fine? Am a bit hesitant to try as i do not want to mess up my pyenv directory.

https://hatch.pypa.io/latest/config/environment/advanced/#python-variables does not tell me how to ensure hatch actually finds the referred pythons.

https://hatch.pypa.io/latest/config/environment/overview/#python-version explains that one could also provide absolute paths but that would not be very helpful when setting this in pyproject.toml as I am sharing this with other developers. So hard coding a path is not a great option there.

Ideally, hatch would be able to work with pyenv by setting a config setting, providing an env variable, or any other way - but I cannot figure out how...

Any input on how to achieve this?

[jstvz]

Ideally, hatch would be able to work with pyenv by setting a config setting, providing an env variable, or any other way - but I cannot figure out how...

Any input on how to achieve this?

I can't find any references to dirs.python in the codebase outside of DirConfig (maybe it's for a planned feature? 🤷🏾‍♂️).

Hatch's default environment, virtual uses virtualenv to discover python versions, which can't see pyenv's versions:

❯ hatch env show
                  Standalone
┏━━━━━━━━━┳━━━━━━━━━┳━━━━━━━━━━━━━━┳━━━━━━━━━┓
┃ Name    ┃ Type    ┃ Dependencies ┃ Scripts ┃
┡━━━━━━━━━╇━━━━━━━━━╇━━━━━━━━━━━━━━╇━━━━━━━━━┩
│ default │ virtual │ pytest       │ cov     │
│         │         │ pytest-cov   │ no-cov  │
└─────────┴─────────┴──────────────┴─────────┘
                        Matrices
┏━━━━━━┳━━━━━━━━━┳━━━━━━━━━━━━┳━━━━━━━━━━━━━━┳━━━━━━━━━┓
┃ Name ┃ Type    ┃ Envs       ┃ Dependencies ┃ Scripts ┃
┡━━━━━━╇━━━━━━━━━╇━━━━━━━━━━━━╇━━━━━━━━━━━━━━╇━━━━━━━━━┩
│ test │ virtual │ test.py37  │ pytest       │ cov     │
│      │         │ test.py38  │ pytest-cov   │ no-cov  │
│      │         │ test.py39  │              │         │
│      │         │ test.py310 │              │         │
│      │         │ test.py311 │              │         │
└──────┴─────────┴────────────┴──────────────┴─────────┘

❯ hatch env create
Environment `default` is incompatible: cannot locate Python: 3.7

❯ hatch run test.py39:cov
Environment `test.py39` is incompatible: cannot locate Python: 39

However, setting multiple Python versions with Pyenv is possible, and allows virtualenv to discover them:

❯ pyenv local 3.8.16 3.9.16 3.10.9 3.11.1 3.7.16

❯ hatch run cov
=================================== test session starts ===================================
platform linux -- Python 3.7.16, pytest-7.2.0, pluggy-1.0.0
rootdir: /tmp/mypkg
plugins: cov-4.0.0
collected 0 items

---------- coverage: platform linux, python 3.7.16-final-0 -----------
Name                    Stmts   Miss  Cover   Missing
-----------------------------------------------------
src/mypkg/__init__.py       0      0   100%
tests/__init__.py           0      0   100%
-----------------------------------------------------
TOTAL                       0      0   100%

================================== no tests ran in 0.01s ==================================

❯ hatch run test.py311:cov
=================================== test session starts ===================================
platform linux -- Python 3.11.1, pytest-7.2.0, pluggy-1.0.0
rootdir: /tmp/mypkg
plugins: cov-4.0.0
collected 0 items


---------- coverage: platform linux, python 3.11.1-final-0 -----------
Name                    Stmts   Miss  Cover   Missing
-----------------------------------------------------
src/mypkg/__init__.py       0      0   100%
tests/__init__.py           0      0   100%
-----------------------------------------------------
TOTAL                       0      0   100%

================================== no tests ran in 0.01s ==================================

[gerbendekkervolue]

Thanks a lot for writing this up. I tried something similar before, but could not get it to work. Your answer seems to work fine for my setup:

1. hatch installed globally through pipx
2. pythons installed through pyenv

How to test whether this works for others:

• make a new hatch project using hatch new
• in the resulting folder, point to the python versions you need hatch to have available using pyenv local 3.x, 3.y as explained above
• test by running hatch run test.pyX:cov as demonstrated above.

[ofek]

FYI in the documentation I'm going to begin discouraging the use of pyenv now that we have these features:

• Implement Python management #970
• Automatically download Python distributions for virtual environments #1002

[icfly2]

In my corporate setting I can manage python with uv, but hatch runs into ssl cert issues I’m not able to resolve.

would be nice if one could override the behaviour of hatch to install python and just use paths