Minimal handler

def handler(request):
    request.stdout.write('\r\n'.join((
        'Status: 200 OK',
        'Content-type: text/plain',
        '',
        'Hello, World!',
        )))

if __name__ == '__main__':
    from gevent_fastcgi.server import FastCGIServer

    FastCGIServer('/path/to/unix/socket', handler).serve_forever()