Bad Gateway and TypeError while using Nginx, Flask_SocketIO, and uWSGI+Gevent.

[razaaliabid87]

I am working on Nginx, Flask_SocketIO, and uWSGI+Gevent. Whenever I run my code in the docker container I always ended up with a 502 Bad Gateway error.

Here is my __init__ file.
app/__init__.py

monkey.patch_all()
from flask import Flask
from flask_socketio import SocketIO
app = Flask(__name__)
app.config['SECRET_KEY'] = 'secret!'
socketio = SocketIO(app, async_mode=None, logger=True, engineio_logger=True)
from app import views

run.py.

from app import app
from app import socketio
if __name__ == "__main__":
    socketio.run(app, host='0.0.0.0', port = 8084)

nginx.conf

server {
    listen 80;
    location /vsoTS {
        proxy_set_header Host $http_host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_pass http://0.0.0.0:8084;
    }
    location /socket.io {
        proxy_set_header Host $http_host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;

        proxy_http_version 1.1;
        proxy_buffering off;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "Upgrade";
        proxy_pass http://0.0.0.0:8084/socket.io;
    }
}

uWSGI configuration resides in the .ini file.
app.ini

[uwsgi]
wsgi-file = run.py
callable = app
processes = 4
threads = 2
master = true
chmod-socket = 660
vacuum = true
mount = /=run.py
manage-script-name = true
die-on-term = true
module = run:app
buffer-size=32768
gevent = 1000
http-websockets = true
http-socket = 0.0.0.0:8084
single-interpreter = true
protocol = http

requirements.txt

gevent==21.1.2
greenlet==1.1.0
zope.event==4.5.0
zope.interface==5.4.0
pycparser==2.20
cffi==1.14.6

click==8.0.1
colorama==0.4.4
Flask==2.0.1
itsdangerous==2.0.1
Jinja2==3.0.1
MarkupSafe==2.0.1
uWSGI==2.0.18
Werkzeug==2.0.1
python-engineio==3.13.2
python-socketio==4.6.0
Flask-SocketIO==4.3.1

When I run this I get an error TypeError: 'module' object is not callable. the response to the docker-compose up command is given below.

vsots     | Server initialized for gevent_uwsgi.
vsots     | Server initialized for gevent_uwsgi.
vsots     | WSGI app 0 (mountpoint='') ready in 1 seconds on interpreter 0x561d019af7c0 pid: 1 (default app)
vsots     | mounting run.py on /
vsots     | WSGI app 1 (mountpoint='/') ready in 0 seconds on interpreter 0x561d019af7c0 pid: 1
vsots     | uWSGI running as root, you can use --uid/--gid/--chroot options
vsots     | *** WARNING: you are running uWSGI as root !!! (use the --uid flag) ***
vsots     | spawned uWSGI master process (pid: 1)
vsots     | spawned uWSGI worker 1 (pid: 8, cores: 2)
vsots     | *** running gevent loop engine [addr:0x561d016e4cf0] ***
vsots     | TypeError: 'module' object is not callable
vsots     | TypeError: 'module' object is not callable
vsots     | TypeError: 'module' object is not callable
vsots     | spawned uWSGI worker 2 (pid: 9, cores: 2)
vsots     | spawned uWSGI worker 3 (pid: 10, cores: 2)
vsots     | TypeError: 'module' object is not callable
vsots     | TypeError: 'module' object is not callable
vsots     | TypeError: 'module' object is not callable
vsots     | spawned uWSGI worker 4 (pid: 11, cores: 2)
vsots     | TypeError: 'module' object is not callable
vsots     | TypeError: 'module' object is not callable
vsots     | TypeError: 'module' object is not callable
vsots     | TypeError: 'module' object is not callable
vsots     | TypeError: 'module' object is not callable
vsots     | TypeError: 'module' object is not callable

Nginx Logs

nginx     | 2021/07/13 23:46:34 [error] 28#28: *5 connect() failed (111: Connection refused) while connecting to upstream, client: 172.18.0.1, server: , request: "GET /vsoTS HTTP/1.1", upstream: "http://0.0.0.0:8084/vsoTS", host: "192.168.43.26"
nginx     | 172.18.0.1 - - [13/Jul/2021:23:46:34 +0000] "GET /vsoTS HTTP/1.1" 502 157 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:89.0) Gecko/20100101 Firefox/89.0" "-"

Please help me to get out of this problem thank you in anticipation.

[miguelgrinberg]

Your uWSGI start up command seems to be incorrect.

TypeError: 'module' object is not callable

[razaaliabid87]

Actually, I am not running uWSGI manually. I am running it through Dockerfile. Here is my Dockerfile please take a look and give me your dictation of what is wrong with it?
Dockerfile

FROM python:3.9.5-buster
WORKDIR /app
ADD . /app
RUN pip install -r requirements.txt
CMD ["uwsgi", "app.ini"]

To build and run I use the docker-compose .yml file which is,

version: "3.9"
services:
  vsots:
    build: ./vsots
    container_name: vsots
    restart: always
    environment:
      - APP_NAME=MyVsoTS
    expose:
      - 8084

[miguelgrinberg]

I can't really tell you what's wrong, this is something that you need to debug. The error suggest the configuration in your ini file is wrong, probably the module variable, but I really have no way to know for sure.

[razaaliabid87]

I found after running my code again and again that when I use Gevent and monkey pathing this problem raises otherwise my app runs in a good manner. now, what is the suggestion from you? your response will be appreciated.

[miguelgrinberg]

Using uWSGI without gevent is not something I ever intended to support. For certain you will not have access to websocket if you do that. Other aspects of the Socket.IO may also fail to work. So I wouldn't consider that an option, unless you are prepared to debug and investigate problems on your own.

Now going back to the standard usage with gevent, I don't really have any additional information to change my answer. I suggest you try a different application, like the one in the example directory in this repository. If you can reproduce your problem with my example application, then maybe there is something we can discuss.