uv pip install --directory not working when called with a Python subprocess

[djalan]

Hello

Sample repo? Yes! https://github.com/djalan/uv-pip-install-subprocess

Here is the problem:

As per your documentation @ https://docs.astral.sh/uv/pip/environments/#discovery-of-python-environments

When running a command that mutates an environment such as uv pip sync or uv pip install, uv will search for a virtual environment in the following order:

• An activated virtual environment based on the VIRTUAL_ENV environment variable.
• An activated Conda environment based on the CONDA_PREFIX environment variable.
• A virtual environment at .venv in the current directory, or in the nearest parent directory.

This becomes a problem when you are calling uv using a subprocess.Popen from a Python project that is using a virtual env.

It won't take into consideration the --directory switch and changing cwd current working directory for subprocess.Popen does not resolve the issue.

Using Python 3.11.7 environment at: D:\workspace\project-running-subprocess\.venv
Audited 166 packages in 53ms

print("Install dependencies with 'uv'")
with subprocess.Popen(
    [
        definitions.UV_EXE,
        "pip",
        "install",
        "--directory",
        clone_fullpath.absolute().as_posix(),
        "--no-progress",
        "--color",
        "never",
        "-r",
        requirements_path,
    ],
    stdout=subprocess.PIPE,
    bufsize=1,
    universal_newlines=True,
    cwd=clone_fullpath,
) as proc:
    for line in proc.stdout:
        print(line, end="")

On the other hand, uv venv honors the --directory switch and creates the .venv at the desired location.

print("Create venv with 'uv'")
with subprocess.Popen(
    [
        definitions.UV_EXE,
        "venv",
        "--no-progress",
        "--color",
        "never",
        "--directory",
        clone_fullpath.absolute().as_posix(),
    ],
    stdout=subprocess.PIPE,
    bufsize=1,
    universal_newlines=True,
    cwd=clone_fullpath,
) as proc:
    for line in proc.stdout:
        print(line, end="")

I would fix the problem and amend the documentation and give --directory the biggest priority.

• The --directory switch on the command line
• An activated virtual environment based on the VIRTUAL_ENV environment variable.
• An activated Conda environment based on the CONDA_PREFIX environment variable.
• A virtual environment at .venv in the current directory, or in the nearest parent directory.

[zanieb]

I think you just want uv pip install --python <path-to-venv> instead of using --directory? Changing the working directory via --directory shouldn't change our Python discovery behavior, in my opinion. It should be the same as if you invoked uv from that directory.

[zanieb]

(Thank you for all the details and the reproduction!)

[djalan]

Hello

Your solution works! I pushed it to the repo.

Maybe consider adding [PATH] at the end of uv pip install just like uv venv.
That would replace the --python switch.

Right now it looks like this:

Usage: uv.exe venv [OPTIONS] [PATH]

Usage: uv.exe pip install [OPTIONS] <PACKAGE|--requirements <REQUIREMENTS>|--editable <EDITABLE>>