Allow environment variables expansion in pyproject.toml

[ShaiAvr]

A feature I'd really like to see implemented is the ability to expand environment variables in the pyproject.toml file. My use-case is as follows: I am working on a library to simplify my work on other projects. In the future, I'd like to publish the library to PyPi. When I work on my projects, however, I want to use my library as a local editable dependency so I can quickly make changes and see them applied. So I have an example project with the following pyproject.toml:

[project]
name = "demo"
version = "0.1.0"
description = "Add your description here"
readme = "README.md"
requires-python = ">=3.12"
dependencies = [
    "my-lib",
]

[tool.uv.sources]
my-lib = { path = "/path/to/my/library/my-lib", editable = true }

The problem is I am using an absolute path for my library, so I need to modify it if I work on multiple computers, and it's not something I'd want to push to GitHub. A better solution would be to have an environment variable that defines the location of the library on my local machine: MY_LIB_PATH="/path/to/my/library/my-lib". That way, I can define the environment variable as necessary on different machines and my pyproject.toml file will simply use this variable:

[project]
name = "demo"
version = "0.1.0"
description = "Add your description here"
readme = "README.md"
requires-python = ">=3.12"
dependencies = [
    "my-lib",
]

[tool.uv.sources]
my-lib = { path = "${MY_LIB_PATH}", editable = true }

This isn't possible at the moment, and I think expanding environment variables in the pyproject.toml file could solve my use case and other similar use cases.

[woutervh]

I would reference a local symlink src/my-lib --> /absolute/path/to/my-lib

[ShaiAvr]

@woutervh I don’t think a symbolic link should be uploaded to git. The contents of the link won’t be portable.

[charliermarsh]

Similar (but not identical) to #5734.

[dpnova]

would love to be able to do something like this:

[tool.uv.sources]
foo = { git = "https://${GITHUB_TOKEN}@github.com/fooco/foo.git" }

edit: just saw the other discussion - perhaps more relevant than here

[kwaegel]

I would also find this useful.

Context: I have a CMake projects that generates Python Protobuf bindings in an out-of-source build tree, copies over a templated pyproject.toml file, and builds a wheel.

Separately, several other Python projects needs to consume the bindings package, but there is no reliable way to use relative paths as the build tree is not under the source tree (typical for CMake projects).

My current options are:

• Copy the generated bindings directly into each project that needs to consume them via Makefile or something.
• Copy the generated bindings back into the source tree as part of the build process, so they're in a stable location.