setuptools Quickstart#

Installation#

To install the latest version of setuptools, use:

pip install --upgrade setuptools

Python packaging at a glance#

The landscape of Python packaging is shifting and Setuptools has evolved to only provide backend support, no longer being the de-facto packaging tool in the market. All python package must provide a pyproject.toml and specify the backend (build system) it wants to use. The distribution can then be generated with whatever tools that provides a build sdist-alike functionality. While this may appear cumbersome, given the added pieces, it in fact tremendously enhances the portability of your package. The change is driven under PEP 517. To learn more about Python packaging in general, navigate to the bottom of this page.

Basic Use#

For basic use of setuptools, you will need a pyproject.toml with the exact following info, which declares you want to use setuptools to package your project:

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

Then, you will need a setup.cfg or setup.py to specify your package information, such as metadata, contents, dependencies, etc. Here we demonstrate the minimum

[metadata]
name = mypackage
version = 0.0.1

[options]
packages = mypackage
install_requires =
    requests
    importlib; python_version == "2.6"

from setuptools import setup

setup(
    name='mypackage',
    version='0.0.1',
    packages=['mypackage'],
    install_requires=[
        'requests',
        'importlib; python_version == "2.6"',
    ],
)

This is what your project would look like:

~/mypackage/
    pyproject.toml
    setup.cfg # or setup.py
    mypackage/__init__.py

Then, you need an builder, such as PyPA build which you can obtain via pip install build. After downloading it, invoke the builder:

python -m build

You now have your distribution ready (e.g. a tar.gz file and a .whl file in the dist directory), which you can upload to PyPI!

Of course, before you release your project to PyPI, you’ll want to add a bit more information to your setup script to help people find or learn about your project. And maybe your project will have grown by then to include a few dependencies, and perhaps some data files and scripts. In the next few sections, we will walk through those additional but essential information you need to specify to properly package your project.

Automatic package discovery#

For simple projects, it’s usually easy enough to manually add packages to the packages keyword in setup.cfg. However, for very large projects , it can be a big burden to keep the package list updated. setuptools therefore provides two convenient tools to ease the burden: find: and find_namespace:. To use it in your project:

[options]
packages = find:

[options.packages.find] #optional
include=pkg1, pkg2
exclude=pk3, pk4

When you pass the above information, alongside other necessary ones, setuptools walks through the directory specified in where (omitted here as the package reside in current directory) and filters the packages it can find following the include (default to none), then remove those that match the exclude and return a list of Python packages. Note that each entry in the [options.packages.find] is optional. The above setup also allows you to adopt a src/ layout. For more details and advanced use, go to Package Discovery and Namespace Package

Entry points and automatic script creation#

Setuptools support automatic creation of scripts upon installation, that runs code within your package if you specify them with the entry_points keyword. This is what allows you to run commands like pip install instead of having to type python -m pip install. To accomplish this, add the entry_points keyword in your setup.cfg:

[options.entry_points]
console_scripts =
    main = mypkg:some_func

When this project is installed, a main script will be installed and will invoke the some_func in the __init__.py file when called by the user. For detailed usage, including managing the additional or optional dependencies, go to Entry Points.

Dependency management#

setuptools supports automatically installing dependencies when a package is installed. The simplest way to include requirement specifiers is to use the install_requires argument to setup.cfg. It takes a string or list of strings containing requirement specifiers (A version specifier is one of the operators <, >, <=, >=, == or !=, followed by a version identifier):

[options]
install_requires =
    docutils >= 0.3
    requests <= 0.4

When your project is installed, all of the dependencies not already installed will be located (via PyPI), downloaded, built (if necessary), and installed. This, of course, is a simplified scenarios. setuptools also provide additional keywords such as setup_requires that allows you to install dependencies before running the script, and extras_require that take care of those needed by automatically generated scripts. It also provides mechanisms to handle dependencies that are not in PyPI. For more advanced use, see Dependencies Management in Setuptools

Including Data Files#

The distutils have traditionally allowed installation of “data files”, which are placed in a platform-specific location. Setuptools offers three ways to specify data files to be included in your packages. For the simplest use, you can simply use the include_package_data keyword:

[options]
include_package_data = True

This tells setuptools to install any data files it finds in your packages. The data files must be specified via the distutils’ MANIFEST.in file. For more details, see Data Files Support

Development mode#

Tip

Prior to pip v21.1, a setup.py script was required to be compatible with development mode. With late versions of pip, any project may be installed in this mode.

setuptools allows you to install a package without copying any files to your interpreter directory (e.g. the site-packages directory). This allows you to modify your source code and have the changes take effect without you having to rebuild and reinstall. Here’s how to do it:

pip install --editable .

This creates a link file in your interpreter site package directory which associate with your source code. For more information, see “Development Mode”.

Uploading your package to PyPI#

After generating the distribution files, next step would be to upload your distribution so others can use it. This functionality is provided by twine and we will only demonstrate the basic use here.

Transitioning from setup.py to setup.cfg#

To avoid executing arbitrary scripts and boilerplate code, we are transitioning into a full-fledged setup.cfg to declare your package information instead of running setup(). This inevitably brings challenges due to a different syntax. Here we provide a quick guide to understanding how setup.cfg is parsed by setuptool to ease the pain of transition.

Resources on Python packaging#

Packaging in Python is hard. Here we provide a list of links for those that want to learn more.