Local mirror of compiled python packages with pip wheel and devpi server

This post is updated on 3rd of March 2016. If you would like to see what changed check github commit history

A problem.

pip install can take quite a while when we try to install packages as big as scikit-learn or scipy from source. Especially if you’re installing it quite often within virtualenv and not on that powerful vagrant virtual machine.

Meet the wheel.

wheel is “a built-package format for Python”.

This is the replacement for the egg format which never had proper pep specification. Wheel gives us an option to create binary “package” by ourself. If there already is .whl uploaded to pypi pip wheel will download and use it.

pip wheel can create binaries and with help of devpi-builder it’s easy to create local mirror of compiled packages.

Using devpi-builder to build packages.

Create virtualenv for every requirements.txt file for which I want to build wheels.

virtualenv venv

Install all dependencies from requirements.txt file

source venv/bin/activate
pip install -r requirements.txt

I’m doing this step just as précaution because for example scikit-learn needs numpy installed to build but numpy is not added as dependency.

devpi installation/configuration

Installation of devpi is the easiest part:

pip install devpi-server devpi-client devpi-web devpi-builder

To make it easier to start/stop service I also created user in the system called devpi and enabled systemd to run processess for users even if they logged out.

The .service file looks like this:

[Unit]
Description=local devpi mirror
After=network.target

[Service]
Type=forking
PIDFile=/var/run/devpi-server.PID
Restart=always
ExecStart=/usr/local/bin/devpi-server --start --serverdir /home/$USER/mirror/
ExecStop=/usr/local/bin/devpi-server --stop --serverdir /home/$USER/mirror/

[Install]
WantedBy=multi-user.target

File was copied to /home/$USER/.config/systemd/user/devpi.service and the service was started with

systemctl --user enable devpi.service
systemctl --user start devpi.service

Now it’s time to configure our local mirror.

devpi use http://localhost:3141
devpi user -c $USER password=TEST_PASSWORD
devpi login $USER --password=TEST_PASSWORD
devpi index -c mirror

Building and uploading packages to devpi server

source venv/bin/activate
devpi-builder requirements.txt http://localhost:3141/$USER/mirror $USER TEST_PASSWORD

And now we have our locally available packages which we can use even if the internet (or pypi) is down.

pip install -i http://localhost:3141/$USER/mirror/ -r requirements.txt

Demo/example.

From now you can go to devpi-setup-example repository and test it with vagrant or just see scripts with simple devpi installation.

Global pip configuration with fallback to pypi

And the last thing I wanted to do is to create pip config which can be used everywhere. When the local mirror is not available/dead/broken it’s going to download packages from pypi.

[global]
index-url = http://localhost:3141/$USER/mirror/
extra-index-url = https://pypi.python.org/simple/
retries = 0

Where to put this pip.conf you can find on pip documentation page

Problems

I’m using this method to build packages for python2 and python3. It takes about 3 hours right now for me so this is not the most efficient way.

This is why I’m going to write script taking all the dependencies across repositories, checks versions and builds all the things I need. It’s going to be totally for my use case but I think I’ll opensource it and maybe hack a little around pip APIs.