Suppose we want to have a private Python PyPI repository shared among the development machines for the packages that our projects depend on. There is a whole slew of solutions to that problem available on the Internet. Most of them propose a quite complicated setup, typically involving a web server. There are also companies offering package hosting.

Does it have to be so complicated? After all, a Python package is just a file, so a simple package repository should be a directory because this is the canonical way of making files accessible on a UNIX system.

In this article, I will show how to configure pip to use a directory as an additional source of packages.

The method

One of my Python packages, signaldb, employs the usual setup.py script to generate signaldb-x.y.z.whl package files. Instead of using a Makefile to call the build script and deploy the wheel (a kind of Python package), I wrote the following 3 lines-long bash equivalent generating and copying the wheel to a “repository” located at $local_pypi. The $local_pypi environmental variable is conveniently defined in my .profile and points to ~/packages directory.

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#!/bin/bash

set -e; set -u

python setup.py bdist_wheel
cp dist/*.whl ${local_pypi}

The easiest way to install signaldb package with pip is to specify the wheel file explicitly:

pip install ${local_pypi}/signaldb-0.0.1.whl

It is also possible to install the package just by typing

pip install signaldb

For that, we first need to inform pip where to look for the package. An additional repository supplementing pypi.python.org can be specified with

pip install --extra-index-url "file://${local_pypi}/"

or, by exporting an environmental variable associated with that pip option:

export PIP_EXTRA_INDEX_URL="file://${local_pypi}/"

This alone won’t work, though. The PyPI repository needs to obey PEP 503: Each package must reside in its own subdirectory named after the package, and the root directory of the repository must contain an index.html file with links to the package files.

Luckily, there is a Python tool called pip2pi that can convert a directory containing a bunch of wheel files into a properly structured PyPI repository. pip2pi exposes the command-line utility dir2pi generating a PyPI repository in the subdirectory simple of a directory specified in the argument:

dir2pi -n ${local_pypi}

(the -n option normalizes the package names to conform with PEP 503) In our case we get

packages/simple/index.html
packages/simple/signaldb
packages/simple/signaldb/signaldb-0.0.1-py3-none-any.whl
packages/simple/signaldb/signaldb-0.0.2-py3-none-any.whl
packages/simple/signaldb/index.html

The above wheel files are just symlinks to the wheels from the source directory. Finally, we need to update .profile or .bashrc

export PIP_EXTRA_INDEX_URL="file://${local_pypi}/simple/"

and invoke pip in a familiar way:

$ pip install signaldb
Collecting signaldb
[...]
Successfully installed signaldb-0.0.2 [...]

Conclusion

The outlined method shows that a simple private PyPI repository does not require a server component. Such a repository can handle multiple package versions and can easily be synchronized among multiple machines using tools like syncthing or similar.

References