Setuptools plugin for Rust extensions

setuptools-rust is a plugin for setuptools to build Rust Python extensions implemented with PyO3 or rust-cpython.

Compile and distribute Python extensions written in Rust as easily as if
they were written in C.

Quickstart

The following is a very basic tutorial that shows how to use setuptools-rust in pyproject.toml.
It assumes that you already have a bunch of Python and Rust files that you want
to distribute. You can see examples for these files in the
examples/hello-world
directory in the github repository.
The PyO3 docs have detailed information on how to write Python
modules in Rust.

hello-world
├── python
│   └── hello_world
│       └── __init__.py
└── rust
    └── lib.rs

Once the implementation files are in place, we need to add a pyproject.toml
file that tells anyone that wants to use your project how to build it.
In this file, we use an array of tables
(TOML jargon equivalent to Python's list of dicts) for [[tool.setuptools-rust.ext-modules]],
to specify different extension modules written in Rust:

# pyproject.toml
[build-system]
requires = ["setuptools", "setuptools-rust"]
build-backend = "setuptools.build_meta"

[project]
name = "hello-world"
version = "1.0"

[tool.setuptools.packages]
# Pure Python packages/modules
find = { where = ["python"] }

[[tool.setuptools-rust.ext-modules]]
# Private Rust extension module to be nested into the Python package
target = "hello_world._lib"  # The last part of the name (e.g. "_lib") has to match lib.name in Cargo.toml,
                             # but you can add a prefix to nest it inside of a Python package.
path = "Cargo.toml"      # Default value, can be omitted
binding = "PyO3"         # Default value, can be omitted

Each extension module should map directly into the corresponding [lib] table on the
Cargo manifest file:

# Cargo.toml
[package]
name = "hello-world"
version = "0.1.0"
edition = "2021"

[dependencies]
pyo3 = "0.25"

[lib]
name = "_lib"  # private module to be nested into Python package,
               # needs to match the name of the function with the `[#pymodule]` attribute
path = "rust/lib.rs"
crate-type = ["cdylib"]  # required for shared library for Python to import from.

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
# See also PyO3 docs on writing Cargo.toml files at https://pyo3.rs

You will also need to tell Setuptools that the Rust files are required to build your
project from the source distribution.
That can be done either via MANIFEST.in (see example below) or via a plugin like
setuptools-scm.

# MANIFEST.in
include Cargo.toml
recursive-include rust *.rs

With these files in place, you can install the project in a virtual environment
for testing and making sure everything is working correctly:

# cd hello-world
python3 -m venv .venv
source .venv/bin/activate  # on Linux or macOS
.venv\Scripts\activate     # on Windows
python -m pip install -e .
python
>>> import hello_world
# ... try running something from your new extension module ...
# ... better write some tests with pytest ...

Environment variables for configuration

As well as all environment variables supported by Cargo, setuptools-rust also supports the following:

SETUPTOOLS_RUST_CARGO_PROFILE: used to override the profile of the Rust build. Defaults to release, e.g. set to dev to do a debug build.

Next steps and final remarks

Dependencies of setuptools-rust (2).
Dependency	Optional
semantic_version	false
setuptools	false

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setuptools-rust

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