Interference with local python releases

[krstp]

First, thank you for a great tool which is uv. I am really enjoying it.

However, I am running into issue. Conflicts with existing python installations. It turns out:

• I have system wide python 3.12.6 version, probably installed with brew
• I have other python releases (multiple versions) installed with pyenv

Now a gist:

• I do have 3.12.4 installed with uv, no problem here; everything works as desired.
• when specifying in .python-version version 3.12.6 regardless of what command I invoke with uv I get the following error:

pyenv: version `3.12.6' is not installed (set by /Users/<user>/<dev_path>/sample_git_project/.python-version)

I was trying to go through ~/.config/uv and ~/.local/ but I am not finding any json or other conf file that would allow me to re/point to the right python release ~/.local/share/uv/python/cpython-3.x...

Any tips would be appreciated.

[zanieb]

Hm that looks like a pyenv error message not a uv error message. Can you share more of the error with the -v flag? If there's not more I presume this is some sort of pyenv shell hook?

[krstp]

This is also not clear to me. After running uv venv the .venv is created and looking inside it I see uv creates pyvenv.cfg, but despite even changing it to the install of my liking say 3.12.6 path instead of 3.12.4 it will still revert to .4 🤔

And indeed, weirdly uv picks up pyenv version not the uv installed version and I am having trouble finding where could this be defined in uv 🤔

uv -v venv does not yield any additional input.

The solution here would be to force uv to use its own install.... and sorry, but I will not be uninstalling pyenv, this is what I used to rely on and still large part of my solution run on it, before I battle-test the uv ;)

[krstp]

Rather my main question is... where does the uv config live, where does it pick up given python version?

When I type uv python list it will show me what version are installed where, but even if 3.12.6 is the one from uv it will still somehow pick up previously installed version with brew; BTW: pyenv does not have 3.12.6 in its repository (or I haven't updated mine), so this is also weird that it reference pyenv 🤔

Ref from uv python list:

cpython-3.13.0rc2-macos-aarch64-none    <download available>
cpython-3.12.6-macos-aarch64-none       /Users/<user>/.local/share/uv/python/cpython-3.12.6-macos-aarch64-none/bin/python3 -> python3.12
[...]

[krstp]

Some more insight (notice instantiation of 3.12.6 but cfg set with 3.12.4):

~/<path>/sample_git_project> uv python --python-preference managed install 3.12.6
Searching for Python versions matching: Python 3.12.6
Found existing installation for Python 3.12.6: cpython-3.12.6-macos-aarch64-none

~/<path>/sample_git_project > uv venv 3.12.6 
Using Python 3.12.4
Creating virtual environment at: 3.12.6
Activate with: source 3.12.6/bin/activate

~/<path>/sample_git_project> cat 3.12.6/pyvenv.cfg                                                                                                                                                                                                                                                                                                                                                                                                                                                               
       │ File: 3.12.6/pyvenv.cfg
   1   │ home = /Users/<user>/.local/share/uv/python/cpython-3.12.4-macos-aarch64-none/bin
   2   │ implementation = CPython
   3   │ uv = 0.4.13
   4   │ version_info = 3.12.4
   5   │ include-system-site-packages = false

~/<path>/sample_git_project> source 3.12.6/bin/activate

~/<path>/sample_git_project> python -version
Python 3.12.4

😩
But...

~/<path>/sample_git_project> ~/.local/share/uv/python/cpython-3.12.6-macos-aarch64-none/bin/python3.12 --version

Python 3.12.6

So all there seems is to change some underlying cfg pointer, but changing the .venv/pyvenv.cfg value does not work... as soon as I run uv venv it somehow gets overwritten with 3.12.4 version :/

[zanieb]

Sounds like you want to create a uv.toml for your user (https://docs.astral.sh/uv/configuration/files/)

Then change the python-preference to only-managed (https://docs.astral.sh/uv/reference/settings/#python-preference)

[zanieb]

uv venv 3.12.6 creates a directory called 3.12.6. You want uv venv --python 3.12.6

[krstp]

So...

• created ~/.config/uv/uv.toml so it will be used globally, the content of the file is:

python-preference = "managed"

• I also copied the same file into project directory

Then I run python --version as well as uv venv --python 3.12.6 and in each case I get:

pyenv: version `3.12.6' is not installed (set by /Users/<path>/sample_git_project/.python-version)

[krstp]

Update:

I have manually disabled pyenv from the whole env: PATH=$(echo $PATH | tr ':' '\n' | grep -v pyenv | tr '\n' ':' | sed 's/:$//')
then uv venv --verbose
This way I get feedback on 3.12.6 avaibility:

Using Python 3.12.6
Creating virtual environment at: .venv
DEBUG Removing existing directory
Activate with: source .venv/bin/activate

but source .venv/bin/activate doesn't do a thing, such as:

> python --version                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
zsh: command not found: python

on the other hand:

> .venv/bin/python --version                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
Python 3.12.6

checking python installation path more:

> which python
python not found

> which python3
/opt/homebrew/bin/python3  (btw: this is brew install with 3.12.5)

but

> uv python find                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
/Users/<path>/sample_git_project/.venv/bin/python3

So in summary, now .venv carries right python version, but global aliases to python and python3 will not recognize it 🤔

[krstp]

OK, never mind. I opened a fresh terminal and reloaded .zshrc ... whatever I have setup up upon deactivation it still seems to stay into somehow initialized under the hood pyenv (this is my global setup), but at least now everything works. I will close it for how. If this comes back I will reopen.

[krstp]

One detail should be added here for reference, the folder I was tested it in was nested in the other folder that already had uv init; this means it was double nested .venv without activation and I believe this was party the reason why it was referencing external (one level up) .venv.

I hope this helps to pin point the exact uv behavior.

Otherwise #7562 catches the behavior quite well.