Consider adding build to the "seed" packages

[charlesnicholson]

uv venv --seed installs + upgrades setuptools, pip, and wheel, which implies that its purpose is to facilitate distribution package creation. The recent distribution-packaging overhaul over the past few years in the Python world makes build also a critical package. Would you consider adding it to the --seed set?

https://packaging.python.org/en/latest/tutorials/packaging-projects/#generating-distribution-archives

[zanieb]

Thanks for the feedback!

Is there another virtual environment tool that does this? Are there issues for this in venv, virtualenv, or other tools? Generally we'd like to come to decisions like this with a broad consensus in the community.

[charlesnicholson]

venv doesn't appear to even install wheel, but I guess venv is kinda bare-bones (and so very slow).

virtualenv appears to only seed some combination of setuptools, wheel, and pip: https://virtualenv.pypa.io/en/latest/user_guide.html#seeders

Your point about consensus makes total sense, and uv is fast enough that immediately following a seeded venv creation with uv pip install build is fine for us. I just figured I'd flag it since it seems like build is becoming the de-facto build front-end, and the official Python packaging docs are recommending it.

Thanks for reading!

[mitsuhiko]

Generally in a perfect world build would never end up in a virtualenv. I went down this path a few times with rye already and the way it works there is that if you invoke rye build it deals with build in a completely isolated environment. This is from what I can tell also the way other systems already approach this.

For uv it's in a weird spot right now. Medium term it probably would make sense to have a uv build command that triggers the build process, but that might conflict with longer term goals.

[charlesnicholson]

Generally in a perfect world build would never end up in a virtualenv.

In our build (mixed C, C++, Python, firmware, host tools, etc) we use the built-in vanilla venv package to create an isolated virtual environment so that the programmer's host OS and developer-specific setup is irrelevant and doesn't influence the build or cause build divergences. We manually bootstrap the setuptools, wheel, pip, and build packages into that virtual environment, and then our build system has targets for editable package installations, wheel builds / distribution packages, tools that require venv installations (nanopb), etc.

I'm curious what you mean about build never needing to end up in a venv! Do you mean that build should be invoked from the host OS directly, or that Python's build solutions should just be better about isolation in general, or do you mean something else that I'm not understanding yet?

Our (initial) use case for uv is to just have faster-but-still-compatible versions of venv and pip install and shave 30+ seconds off of our build. We also like not diverging too far from the slow-but-well-trodden path of standard Python techniques. From your comment, though, it sounds like maybe you're describing a different use case, where uv ends up fully replacing pip, and how that could behave in the future?

[kvelicka]

I'm curious what you mean about build never needing to end up in a venv! Do you mean that build should be invoked from the host OS directly, or that Python's build solutions should just be better about isolation in general, or do you mean something else that I'm not understanding yet?

build builds stuff by creating a temporary virtualenv, downloading all the build dependencies there and using that to produce the actual artefacts

This means that build doesn't need virtualenv but (IMO) that doesn't mean that it can't/shouldn't be installed in a virtualenv anyway - personally I don't think I'd trust any non-first-party package to be installed directly into my system Python, build included.

[henryiii]

(build maintainer here) I think uv should gain a build subcommand (I might even help work on that in the near future) - see #1510. The producedure is well documented by PEPs and anyone can implement it, including uv (technically, it already has it, it mostly just needs a CLI). The primary purpose of --seed was originally to make a "minimal working environment"; that was setuptools, wheel, and pip. Nowadays, setuptools and wheel aren't needed anymore, so those are no longer included (for backward compat reasons, only on 3.12+). That leaves only pip, and that's not needed if you use uv's (or pip's) targeting feature.

I don't think build is ever intended to be part of a minimal working environment. It's only useful if you need to build wheels or SDists and not everyone needs to do that.

build builds stuff by creating a temporary virtualenv --- personally I don't think I'd trust any non-first-party package

By the way, pip/uv do this too, and all three allow you turn this off by turning off build isolation. And build is just as much or as little of a third-party tool as pip or virtualenv is, all of them are PyPA projects.