app.py

import os
from flask import Flask
from flask.ext.script import Manager
from flask.ext.script import Command
from gunicorn.app.base import Application


FOOBAR = True


def create_app(config=None):
    app = Flask(
        __name__,
        instance_path=os.getcwd(),
        instance_relative_config=True,
    )
    app.config.from_object(__name__)

    if config:
        app.config.from_pyfile(config)
    return app

manager = Manager(create_app)
manager.add_option('-c', dest='config', required=False)


class Gunicorn(script.Command):
    def handle(self, app, *args, **kwargs):
        class GWSGIApp(Application):
            def init(self, parser, opts, args):
                globals, locals = {}, {}
                if opts.config:
                    execfile(opts.config, globals, locals)

                cfg = {}
                for k, v in locals.iteritems():
                    gunicorn_key = k.lstrip('GUNICORN_').lower()
                    if gunicorn_key in self.cfg.settings and v is not None:
                        cfg[gunicorn_key] = v
                return cfg

            def load(self):
                return app

        GWSGIApp().run()


def main():
    manager.add_command('run-gunicorn', Gunicorn())
    manager.run()


if __name__ == '__main__':
    main()

config.py

FOOBAR = False

GUNICORN_WORKER_CLASS = 'gevent'
GUNICORN_WORKERS = 4