How to handle C extensions for python apps with pip?

No. There is no way of including totally separate C library as a part of your build process unless you are writing an extension. Even in that case, you'll need to specify all .c files in ext_modules so that they all can be compiled as a part of your build process, which I know is not what you want.

The only thing you can do is to simply stop the build process and give user a reasonable error if mysql-devel (or libmysqlclient-dev) has not yet been installed.

One way to know if mysql-dev is installed is writing a simple C function that imports mysql.h and check if it is compiled successfully.

Note: mysql.h and my_global.h is part of libmysqlclient-dev package.

---

test/test_mysqlclient.c

// Taken from: http://zetcode.com/db/mysqlc

#include <my_global.h>
#include <mysql.h>

int main(int argc, char **argv)
{
  printf("MySQL client version: %s\n", mysql_get_client_info());
  exit(0);
}

---

Secondly, let's update our setup.py file so that it will be included as a part of the build process.

setup.py

#!/usr/bin/env python

import os
import subprocess

from setuptools import setup, Extension

def mysql_test_extension():
    process = subprocess.Popen(['which', 'mysql_config'],
                               stdout=subprocess.PIPE,
                               stderr=subprocess.PIPE,
                               close_fds=True)

    result, error = process.communicate()
    if process.returncode > 0:
        raise RuntimeError(error)

    config_command = result.strip()

    cflags = subprocess.check_output([config_command, '--cflags'], close_fds=True).strip()

    include_dirs = []
    extra_compile_args = []
    for arg in cflags.split(' '):
        if not arg.strip():
            continue
        elif arg.startswith('-I'):
            include_dirs.append(arg[2:])
        elif arg.startswith('-'):
            extra_compile_args.append(arg)
        else:
            extra_compile_args[-1] = extra_compile_args[-1] + ' ' + arg

    libs = subprocess.check_output([config_command, '--libs'], close_fds=True).strip()

    libraries = []
    linkers = []
    for arg in libs.split(' '):
        if not arg.strip():
            continue
        elif arg.startswith('-L'):
            libraries.append(arg[2:])
        elif arg.startswith('-'):
            linkers.append(arg)
        else:
            linkers[-1] = extra_compile_args[-1] + ' ' + arg

    return Extension('test_mysqlclient', ['test/test_mysqlclient.c'],
                     include_dirs=include_dirs,
                     library_dirs=libraries,
                     extra_link_args=linkers,
                     extra_compile_args=extra_compile_args)



setup(name='python-project',
      version='1.0',
      description='Python Project',
      classifiers=[
          'Development Status :: 5 - Production/Stable',
          'Environment :: Console',
          'Intended Audience :: Developers',
          'License :: OSI Approved :: MIT License',
          'Operating System :: OS Independent',
          'Programming Language :: Python :: 2.7',
          'Natural Language :: English',
      ],
      keywords='mysql python project',
      author='Ozgur Vatansever',
      url='http://github.com/ozgur/python-project/',
      license='MIT',
      packages=['some_project'],
      ext_modules = [mysql_test_extension()]
)

---

You can start building your package along with the test_mysqlclient file:

$ python setup.py build

If mysql-devel is not installed on your system, you'll get an build error similar to this:

test/test_mysqlclient.c:3:10: fatal error: 'my_global.h' file not found
#include <my_global.h>
     ^
1 error generated.