python - 当运行 nginx + python flask + python-daemon : upstream sent unsupported FastCGI protocol version 91

Question

我正在使用 Python Flask 通过 FCGI 和 nginx 运行 Python for web。我的 fcgi 后端设置如下:

#!/usr/bin/env python
import argparse, daemon, os
from flup.server.fcgi import WSGIServer
from fwd_msg import app

SOCKET_LOCATION = '/tmp/fingerprinter-fcgi.sock'

if __name__ == '__main__':
    # arg parse (and daemonize)
    arg_parser = argparse.ArgumentParser()
    arg_parser.add_argument('--daemon', action='store_true', default=False, help='Run as daemon')
    arg_parser.add_argument('--cwd', action='store', default='/', 
                            help='Full path of the working directory to which the process should change on daemon start.')
    arg_parser.add_argument('--uid', action='store', type=int, default=os.getuid(),
        help='The user ID ("UID") value and group ID ("GID") value to switch the process to on daemon start.')
    args = vars(arg_parser.parse_args())

    if args['daemon']:
        context = daemon.DaemonContext(working_directory=args['cwd'], uid=args['uid'])
        with context:
            WSGIServer(app, bindAddress=SOCKET_LOCATION).run()
    else:
        WSGIServer(app, bindAddress=SOCKET_LOCATION).run()

如果我在没有守护进程参数的情况下运行 WSGIServer，它工作正常。

但是如果我使用守护程序参数运行它，我会在 nginx 日志中收到此错误，而对服务器的任何请求都以“502 BAD GATEWAY”结尾:

2012/05/09 12:16:00 [error] 30895#0: *30 upstream sent unsupported FastCGI protocol version: 91 while reading response header from upstream, client: XXX.XXX.XXX.XXX, server: localhost, request: "POST / HTTP/1.1", upstream: "fastcgi://unix:/tmp/fingerprinter-fcgi.sock:", host: "XXX.XXX.XXX.XXX"

知道为什么会发生这种情况以及如何预防吗？

Answer 1

事实证明，DaemonContext 会关闭所有打开的文件描述符，所以基本上应该有一个函数，它实例化 WSGIServer，连同应用程序以及可以在 DaemonContext 中打开文件描述符的所有内容。

还要确保工作目录归用户所有，或者至少具有允许具有给定 UID 的用户在那里写入的权限(不推荐)。

例子:

#!/usr/bin/env python
import argparse, daemon, os
from flup.server.fcgi import WSGIServer
from fwd_msg import app

SOCKET_LOCATION = '/tmp/fingerprinter-fcgi.sock'

def main():
    app = flask.Flask(__name__)
    @app.route('/', methods=['GET'])
    def index():
        pass # your actions here

if __name__ == '__main__':
    # arg parse (and daemonize)
    arg_parser = argparse.ArgumentParser()
    arg_parser.add_argument('--daemon', action='store_true', default=False, help='Run as daemon')
    arg_parser.add_argument('--cwd', action='store', default='/', 
                            help='Full path of the working directory to which the process should change on daemon start.')
    arg_parser.add_argument('--uid', action='store', type=int, default=os.getuid(),
        help='The user ID ("UID") value and group ID ("GID") value to switch the process to on daemon start.')
    args = vars(arg_parser.parse_args())

    if args['daemon']:
        context = daemon.DaemonContext(working_directory=args['cwd'], uid=args['uid'])
        with context:
            main()
    else:
        main()