What's the standard way to package a python project with dependencies?

Question

I have a python project that has a few dependencies (defined under install_requires in setup.py). My ops people requires a package to be self contained and only

Answer 1

In most cases you should be able to "vendor" all the dependencies. It's basically a crude version of virtualenv.

For example look at how the requests package includes chardet and urllib3 in its own source tree. Here's an example script that should do the initial downloading and copying for you: https://gist.github.com/proppy/1136723

Once you have the dependencies installed, you can reference them with from .some.namespace import dependency_name to make sure that you're using your local versions.

Answer 2

There are a few nuances to how pip works. Unfortunately, using --prefix vendor to store all the dependencies of the project doesn't work if any of those dependencies, or dependencies of dependencies are installed into a place where pip can find them. It will skip those dependencies and just install the rest to your vendor folder.

In the past I've used virtualenv's --no-site-packages option to solve this issue. At one company we would ship the whole virtualenv, which includes the python binary. In the interest of only shipping the dependencies, you can combine using a virtualenv with the --prefix switch on pip to give yourself a clean environment that installs to the right place.

I'll provide an example script that creates a temporary virtualenv, activates it, then installs the dependencies to a local vendor folder. This is handy if you are running in CI.

#!/bin/bash

tempdir=$(mktemp -d -t project.XXX) # create a temporary directory
trap "rm -rf $tempdir" EXIT         # ensure it is cleaned up
# create the virtualenv and exclude packages outside of it
virtualenv --python=$(which python2.7) --no-site-packages $tempdir/venv
# activate the virtualenv
source $tempdir/venv/bin/activate    
# install the dependencies as above
pip install -r requirements.txt --prefix=vendor

Answer 3

It's possible to do this with recent versions of pip (I'm using 8.1.2). On the build machine:

pip install -r requirements.txt --prefix vendor

Then run it:

PYTHONPATH=vendor/lib/python2.7/site-packages python yourapp.py

(This is basically an expansion of @valentjedi comment. Thanks!)