---

name: packaging-python-libraries description: Packages and distributes Python libraries using modern pyproject.toml, build backends (setuptools, hatchling), PyPI publishing with trusted publishing, and wheel building. Use when packaging libraries for distribution, publishing to PyPI, or troubleshooting packaging issues.

Python Library Packaging

pyproject.toml Essentials

Copy[build-system]
requires = ["setuptools>=61.0", "wheel"]
build-backend = "setuptools.build_meta"

[project]
name = "my-package"
version = "1.0.0"
description = "Short description"
readme = "README.md"
requires-python = ">=3.10"
license = {text = "MIT"}
dependencies = []

[project.optional-dependencies]
dev = ["pytest>=7.0", "ruff>=0.1", "mypy>=1.0"]

[project.urls]
Homepage = "https://github.com/user/package"
Documentation = "https://package.readthedocs.io"

[project.scripts]
mycli = "my_package.cli:main"

[tool.setuptools.packages.find]
where = ["src"]

Building

Copypip install build
python -m build              # Creates dist/
twine check dist/*           # Validate

Publishing to PyPI

First time setup:

Copy# Create API token at pypi.org/manage/account/token/
export TWINE_USERNAME=__token__
export TWINE_PASSWORD=pypi-xxx...

Publish:

Copytwine upload --repository testpypi dist/*  # Test first
twine upload dist/*                         # Production

GitHub Actions (Trusted Publishing)

Copy# .github/workflows/publish.yml
on:
  release:
    types: [published]

jobs:
  publish:
    runs-on: ubuntu-latest
    permissions:
      id-token: write
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-python@v5
      - run: pip install build && python -m build
      - uses: pypa/gh-action-pypi-publish@release/v1

Dependency Best Practices

Copy# DO: Minimum versions
dependencies = ["requests>=2.28", "click>=8.0"]

# DON'T: Exact pins (locks users)
dependencies = ["requests==2.28.1"]

# DO: Optional for features
[project.optional-dependencies]
cli = ["click>=8.0"]

Including Package Data

Copy[tool.setuptools.package-data]
my_package = ["py.typed", "data/*.json"]

Copyfrom importlib.resources import files
data = files("my_package.data").joinpath("file.json").read_text()

For detailed templates, see:

• PYPROJECT_FULL.md - Complete pyproject.toml
• CONDA.md - Conda packaging guide

Checklist

CopyBefore Release:
- [ ] pyproject.toml valid
- [ ] README.md informative
- [ ] LICENSE file exists
- [ ] Version set correctly
- [ ] twine check passes

After Release:
- [ ] pip install works
- [ ] Import works
- [ ] GitHub release created