Error when running pypi2nix command for a library with C dependencies

[edofic]

Description

I'm packaging an existing Python project which has dependencies that depend on C libraries. I reduced it to a minimal example.

I'm assuming pypi2nix doesn't pick up the libraries brought in by nix-shell and I cannot find a way to specify them. I'm open to working on this if changes to pypi2nix are required, but I'd need some pointers.

Traceback

% pypi2nix --version
1.5.0
% pypi2nix -V 2.7 -r requirements.txt
|-> nix-shell /nix/store/pma8xil24by9kk46ppxsyp3gyg7z5ky6-pypi2nix-1.5.0/pkgs/pypi2nix/pip.nix --argstr pip_build_dir /run/user/1000/pypi2nix/cache/pip --arg requirements_files [ "/run/user/1000/pypi2nix/8363cc83fea44545b2dc0ccefb57f559/2ab60bdd671db0070b6346793281851f.txt" ] --argstr wheel_cache_dir /run/user/1000/pypi2nix/cache/wheel --argstr download_cache_dir /run/user/1000/pypi2nix/cache/download --argstr python_version python27Full --argstr project_dir /run/user/1000/pypi2nix/8363cc83fea44545b2dc0ccefb57f559 -I nixpkgs=/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs:nixos-config=/etc/nixos/configuration.nix:/nix/var/nix/profiles/per-user/root/channels --show-trace --pure --run exit    warning: Nix search path entry ‘/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs:nixos-config=/etc/nixos/configuration.nix:/nix/var/nix/profiles/per-user/root/channels’ does not exist, ignoring
    Collecting dm.xmlsec.binding from git+https://github.com/reciprocity/dm.xmlsec.binding.git#egg=dm.xmlsec.binding (from -r /run/user/1000/pypi2nix/8363cc83fea44545b2dc0ccefb57f559/2ab60bdd671db0070b6346793281851f.txt (line 1))
      Cloning https://github.com/reciprocity/dm.xmlsec.binding.git to /run/user/1000/pypi2nix/cache/pip/dm.xmlsec.binding
        Complete output from command python setup.py egg_info:
        Error : cannot get LibXML2 pre-processor and compiler flags; do you have the `libxml2` development package installed?
        
        ----------------------------------------
    Command "python setup.py egg_info" failed with error code 1 in /run/user/1000/pypi2nix/cache/pip/dm.xmlsec.binding/
    You are using pip version 8.1.2, however version 9.0.1 is available.
    You should consider upgrading via the 'pip install --upgrade pip' command.

[garbas]

@edofic great report. this one was easy to fix :)

what you are missing is providing -E option, which adds system packages to nix-sell
following options built dm.xmlsec.binding for me

% pypi2nix -v -V 2.7 -r requirements.txt -E libxml2 -E libxslt -E xmlsec -E libtool
% nix-build requirements.nix -A interpreter
% ./result/bin/python -c "import dm.xmlsec.binding"

i will close this issue but please reopen if you my solution above does solve your problem.
nice to see reciprocity using nix :)

[edofic]

@garbas yes this works for me. Thank you, I really appreciate your quick support.

About Reciprocity; we are only slowly rolling out nix to power dev environment but it's already solving some problems and causing a lot of developer happiness.

[garbas]

@edofic awesome. i love when things just work 😄 i opened an issue to document -E in readme.

i love seeing Nix growing in Lublana 😉 and feel free to ping if you need any help with python+nix stuff.

also i'm looking for some help moving @garbas/nixpkgs-python forward, that project is intended to share those "override" files with others.

[edofic]

Will do. 😄

That's great. Will contribute any overrides I come up with - cannot really promise anything else right now.