Gunicorn Hello World example

app.py

class App:

    def __call__(self, environ, start_response):
        return self.dispatch(environ, start_response)

    def dispatch(self, environ, start_response):
        """Simplest possible application object"""
        data = b'Hello, World!\n'
        status = '200 OK'
        response_headers = [
            ('Content-type','text/plain'),
            ('Content-Length', str(len(data)))
        ]
        start_response(status, response_headers)
        return iter([data])

my_app = App()

Makefile

run: venv/bin/gunicorn
	venv/bin/gunicorn -b 127.0.0.1:9000 app:my_app

venv/bin/gunicorn:
	test -d venv || pyvenv-3.4 venv
	venv/bin/pip install -U pip
	venv/bin/pip install gunicorn