Flask 引发在 Gunicorn 等 WSGI 服务器上运行的“地址已在使用”答案

【问题标题】：Flask raises `Address already in use` running with a WSGI server such as GunicornFlask 引发在 Gunicorn 等 WSGI 服务器上运行的“地址已在使用”
【发布时间】：2017-07-08 13:18:18
【问题描述】：

我正在尝试使用 Gunicorn 运行我的应用程序。然而，Flask 在 Gunicorn 开始时加注OSError: [Errno 98] Address already in use，然后 Gunicorn 关闭。如何使用 Gunicorn 为应用提供服务？

from flask import Flask

app = Flask(__name__)

@app.route('/')
def index():
    return 'Hello, World!'

app.run(debug=True)

gunicorn app:app

[2017-02-19 21:09:50 -0800] [21965] [INFO] Starting gunicorn 19.6.0
[2017-02-19 21:09:50 -0800] [21965] [INFO] Listening at: http://127.0.0.1:8000 (21965)
[2017-02-19 21:09:50 -0800] [21965] [INFO] Using worker: sync
[2017-02-19 21:09:50 -0800] [21968] [INFO] Booting worker with pid: 21968
 * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
 * Restarting with stat
[2017-02-19 21:09:50 -0800] [21969] [ERROR] Exception in worker process
Traceback (most recent call last):
  File "/home/david/.virtualenvs/py36/lib/python3.6/site-packages/gunicorn/arbiter.py", line 557, in spawn_worker
    worker.init_process()
  File "/home/david/.virtualenvs/py36/lib/python3.6/site-packages/gunicorn/workers/base.py", line 126, in init_process
    self.load_wsgi()
  File "/home/david/.virtualenvs/py36/lib/python3.6/site-packages/gunicorn/workers/base.py", line 136, in load_wsgi
    self.wsgi = self.app.wsgi()
  File "/home/david/.virtualenvs/py36/lib/python3.6/site-packages/gunicorn/app/base.py", line 67, in wsgi
    self.callable = self.load()
  File "/home/david/.virtualenvs/py36/lib/python3.6/site-packages/gunicorn/app/wsgiapp.py", line 65, in load
    return self.load_wsgiapp()
  File "/home/david/.virtualenvs/py36/lib/python3.6/site-packages/gunicorn/app/wsgiapp.py", line 52, in load_wsgiapp
    return util.import_app(self.app_uri)
  File "/home/david/.virtualenvs/py36/lib/python3.6/site-packages/gunicorn/util.py", line 357, in import_app
    __import__(module)
  File "/home/david/Projects/py36/app.py", line 4, in <module>
    app.run(debug=True)
  File "/home/david/.virtualenvs/py36/lib/python3.6/site-packages/flask/app.py", line 841, in run
    run_simple(host, port, self, **options)
  File "/home/david/.virtualenvs/py36/lib/python3.6/site-packages/werkzeug/serving.py", line 691, in run_simple
    s.bind((hostname, port))
OSError: [Errno 98] Address already in use

[2017-02-19 21:09:50 -0800] [21968] [INFO] Worker exiting (pid: 21968)
[2017-02-19 21:09:50 -0800] [21965] [INFO] Shutting down: Master
[2017-02-19 21:09:50 -0800] [21965] [INFO] Reason: Worker failed to boot.

我尝试了gunicorn Connection in use for python flask 和error: [Errno 98] Address already in use，但无法正常工作。

【问题讨论】：

标签： python flask gunicorn

【解决方案1】：

您正在使用 Gunicorn（或任何生产 WSGI 服务器），因此您不想使用 Flask 开发服务器。但是你无条件地打电话给app.run。 Gunicorn 启动，绑定地址，然后导入您的应用程序，该应用程序调用app.run 并尝试启动自己的服务器。但是这个地址已经被 Gunicorn 使用了。

将app.run 移动到保护块中：

if __name__ == '__main__':
    app.run()

或者最好完全删除它，因为您应该使用flask 命令来运行开发服务器，如docs 中所述。

【讨论】：