Popular cryptography library PyNaCl doesn't install.

[fletom]

If you add the package PyNaCl to your requirements and push to Heroku, the build fails.

distutils.errors.DistutilsError: Setup script exited with error: command 'gcc' failed with exit status 1

[fletom]

It turns out this isn't a problem with heroku-buildpack-python, but rather with PyNaCl itself.

I managed to get it working using a combination of two different Heroku buildpacks using heroku-buildpack-multi:

git://github.com/fletom/heroku-buildpack-python-libffi.git
git://github.com/fletom/heroku-buildpack-libsodium.git

This gets around the issue by installing a system-wide copy of libsodium, but the original bug is still there and currently has an active ticket on PyNaCl's issue tracker: pyca/pynacl#79

[lincolnq]

If anyone is Googling and hitting this problem as of now, the solution is to add both PyNaCl and cffi to your requirements file -- you don't need any buildpack hackery anymore. Heroku's default Python buildpack knows how to install libffi but only if cffi is explicitly mentioned! (https://coderanger.net/heroku-cffi/)

[edmorley]

I've opened #296 to avoid the need for explicitly including cffi in the requirements file.

That said IMO people should really start pinning all deps as a matter of default, particularly given the benefits of pip v8's new require-hashes mode. For a not-too-painful workflow, see the suggestions in http://www.kennethreitz.org/essays/a-better-pip-workflow