Post-install script with Python setuptools

Question

Is it possible to specify a post-install Python script file as part of the setuptools setup.py file so that a user can run the command:

python setup.py install

on a local project file archive, or

pip install <name>

for a PyPI project and the script will be run at the completion of the standard setuptools install? I am looking to perform post-install tasks that can be coded in a single Python script file (e.g. deliver a custom post-install message to the user, pull additional data files from a different remote source repository).

I came across this SO answer from several years ago that addresses the topic and it sounds as though the consensus at that time was that you need to create an install subcommand. If that is still the case, would it be possible for someone to provide an example of how to do this so that it is not necessary for the user to enter a second command to run the script?

Answer 1

This solution is more transparent:

You will make a few additions to setup.py and there is no need to an extra file.

Also you need to consider two different post-installations; one for development/editable mode and the other one for install mode.

Add these two classes that includes your post-install script to setup.py:

from setuptools import setup
from setuptools.command.develop import develop
from setuptools.command.install import install


class PostDevelopCommand(develop):
    """Post-installation for development mode."""
    def run(self):
        # PUT YOUR POST-INSTALL SCRIPT HERE or CALL A FUNCTION
        develop.run(self)

class PostInstallCommand(install):
    """Post-installation for installation mode."""
    def run(self):
        # PUT YOUR POST-INSTALL SCRIPT HERE or CALL A FUNCTION
        install.run(self)

and insert cmdclass argument to setup() function in setup.py:

setup(
    ...

    cmdclass={
        'develop': PostDevelopCommand,
        'install': PostInstallCommand,
    },

    ...
)

You can even call shell commands during post-installation, like this:

from setuptools import setup
from setuptools.command.develop import develop
from setuptools.command.install import install
from subprocess import check_call


class PostDevelopCommand(develop):
    """Post-installation for development mode."""
    def run(self):
        check_call("apt-get install this-package".split())
        develop.run(self)

class PostInstallCommand(install):
    """Post-installation for installation mode."""
    def run(self):
        check_call("apt-get install this-package".split())
        install.run(self)


setup(
    ...

P.S. there are no any pre-install entry points available on setuptools. Read this discussion if you are wondering why there is none.

Answer 2

This is the only strategy that has worked for me when the post-install script requires that the package dependencies have already been installed:

import atexit
from setuptools.command.install import install


def _post_install():
    print('POST INSTALL')


class new_install(install):
    def __init__(self, *args, **kwargs):
        super(new_install, self).__init__(*args, **kwargs)
        atexit.register(_post_install)


setuptools.setup(
    cmdclass={'install': new_install},

Answer 3

A solution could be to include a post_setup.py in setup.py's directory. post_setup.py will contain a function which does the post-install and setup.py will only import and launch it at the appropriate time.

In setup.py:

from distutils.core import setup
from distutils.command.install_data import install_data

try:
    from post_setup import main as post_install
except ImportError:
    post_install = lambda: None

class my_install(install_data):
    def run(self):
        install_data.run(self)
        post_install()

if __name__ == '__main__':
    setup(
        ...
        cmdclass={'install_data': my_install},
        ...
    )

In post_setup.py:

def main():
    """Do here your post-install"""
    pass

if __name__ == '__main__':
    main()

With the common idea of launching setup.py from its directory, you will be able to import post_setup.py else it will launch an empty function.

In post_setup.py, the if __name__ == '__main__': statement allows you to manually launch post-install from command line.

Answer 4

I think the easiest way to perform the post-install, and keep the requirements, is to decorate the call to setup(...):

from setup tools import setup


def _post_install(setup):
    def _post_actions():
        do_things()
    _post_actions()
    return setup

setup = _post_install(
    setup(
        name='NAME',
        install_requires=['...
    )
)

This will run setup() when declaring setup. Once done with the requirements installation, it will run the _post_install() function, which will run the inner function _post_actions().

Answer 5

If using atexit, there is no need to create a new cmdclass. You can simply create your atexit register right before the setup() call. It does the same thing.

Also, if you need dependencies to be installed first, this does not work with pip install since your atexit handler will be called before pip moves the packages into place.

Answer 6

Combining the answers from @Apalala, @Zulu and @mertyildiran; this worked for me in a Python 3.5 environment:

import atexit
import os
import sys
from setuptools import setup
from setuptools.command.install import install

class CustomInstall(install):
    def run(self):
        def _post_install():
            def find_module_path():
                for p in sys.path:
                    if os.path.isdir(p) and my_name in os.listdir(p):
                        return os.path.join(p, my_name)
            install_path = find_module_path()

            # Add your post install code here

        atexit.register(_post_install)
        install.run(self)

setup(
    cmdclass={'install': CustomInstall},
...

This also gives you access the to the installation path of the package in install_path, to do some shell work on.