nix-python-uv

What's here

This is a fully-fledged python project controlled by the uv package manager. Firstly there's the main library defined in the pyproject.yaml and in the nix_python_uv folder. There's some scripts, tests, and a few examples of dependencies.

In the Nix setup we define some the build environment, tests, code formatters, and a docker image with the entrypoint ready to run.

What's possible

Regular Python development

python
...
>>> import pandas

Running an entrypoint with nix run ...

nix run .

Running a [script] entrypoint directly

> hello
Hello, world!

> some_script
Hello, world!
Hello, other world!

Building a Docker image

nix build .#docker-image
./result < docker load
docker run nix-python-uv-hello

Testing

You can run the tests with pytest:

pytest

Or, with nix flake check

nix flake check

Note

Running tests like this with Nix is a bit subtle; if the tests are simple; i.e. "pure"; that is, they don't require external dependencies, then they will work.

Code formatting

nix fmt

Note

nix fmt only formats files that are changed; not all files in the repo. For that, run ruff format directly.

Add a new dependency

uv add numpy

Tips and trivia

• Each time you add a new dependency you need to reload the devShell. I have a shell alias, alias rr="direnv reload" for this purpose.

How to use/extend this

For the most part, if you simply make changes with uv this should "Just Work". There will be some busywork if some of the Python dependencies aren't perfectly configured; but all of that can be addressed.

To add a new package, just add it next to pkgs.uv in nix/outputs.nix in the devShells package statement.