1. Use a project having a swift module: requirements.txt: https://github.com/didrocks/python-midi/archive/v0.2.3+2016.11.tar.gz 2. Use the python plugin in your snapcraft.yaml: parts: foo: source: . plugin: python python-version: python2 requirements: requirements.txt build-packages: [swig3.0] After snapcrafting this parts (not a cleanbuild, so swig is available on the system), you will notice that the .so file is compiled: parts/foo/install/lib/python2.7/site-packages/midi/sequencer/_sequencer_alsa.so But you don't have the binding generated by swift, "sequencer_alsa.py". On the same machine, I can create a virtualenv and then get the module compiles: $ virtualenv venv $ . venv/bin/active $ pip install --r requirements.txt -> venv/lib/python2.7/site-packages/midi/sequencer/sequencer_alsa.py was generated As a quick try, I tried removing "--no-compile" in pip_install() in the python plugin, without success. Nothing in the verbose pip outputs explains why swig isn't ran.