Allow setting virtual environment options in `pyproject.toml`

[chrisrodrigue]

When running uv venv, the user may specify the options --system-site-packages and --relocatable. These values persist in .venv/pyenv.cfg as shown:

home = C:\WinPython\python-3.12.4.amd64
implementation = CPython
uv = 0.2.33
version_info = 3.12.4
include-system-site-packages = true
relocatable = true

The uv sync command implicitly creates a virtual environment in .venv, which is awesome. However, it is not possible to pass these options to uv sync or set them in the tool.uv section (or a tool.uv.venv section) of pyproject.toml. The virtual environment created with uv sync always defaults to setting include-system-site-package and relocatable to false.

I propose that uv be capable of reading these from pyproject.toml, and also when passed to uv sync.

Maybe a generalized approach to file-based configuration (both uv.toml and pyproject.toml) of uv behavior could be to support a section corresponding to each uv command for all available options:

Example pyproject.toml demonstrating command customization:

[tool.uv]
no-build-isolation = true
dev-dependencies = []

[uv.tool.venv]
relocatable = true
system-site-packages = true

[uv.tool.sync]
relocatable = true
system-site-packages = true
all-extras = true

# Generalization
[uv.tool.command]
option = value

[charliermarsh]

This seems reasonable to me though want a second opinion before adding any configuration.

[chrisrodrigue]

A more elegant and concise alternative (similar to pdm as shown here - passing constant arguments to every pdm invocation):

[tool.uv.options]
venv = ["--relocatable", "--system-site-packages"]

[zanieb]

I'm kind of hesitant, though I see the benefit. I think it adds a lot of complexity to the configuration and implementation to allow settings to be defined per-command too.

[ssbarnea]

I am still trying to find where I can enable the seed option inside the config as it is causing lots of compatibility issues with lots of tools.

[zanieb]

@ssbarnea please provide more details, what kind of compatibility issues with what tools? Concrete examples are needed to help motivate the change.

[RmStorm]

I have a problem with this as well. Basically if the venv gets created by uv, the flags in pyvenv.cfg are wrong and the code doesn't work. I need apt installed packages on raspberry for the pins to be available in python so uv add or pip install will yield a broken setup. This means that I must run uv venv --system-site-packacges .venv before I can run the code like so: uv run code.py. It would be a lot easier to transfer ownership of this to my less software inclined colleagues if they could just uv run things!

[woutervh]

uv 0.7.3

Given a python-project and a pyproject.toml, is there currently a way to reliably always create the venv with --relocatable?

I. e. without manually creating the venv and typing command-line options each time? (I did not find any other way in the docs)

IMHO this would indeed be a nice syntax:

...
[uv.tool.venv]
relocatable = true
...