Flask, nginx, and uwsgi

Question

My flask app looks like this...
myapp.py

from flask import Flask  
app = Flask(__name__) 

@app.route("/")  
def hello():  
   return "Hello World!"  

if __name__ == "__main__":  
   app.run('0.0.0.0')

My nginx setup

server {
         root /home/admin.jeremylspencer.com;
         server_name admin.jeremylspencer.com;

         location / { try_files $uri @yourapplication; } 
         location @yourapplication {
                 include uwsgi_params;
                 uwsgi_pass unix:/tmp/uwsgi.sock;
         }       

         #error_page 404 /404.html;
         #error_page 500 502 503 504 /50x.html;
         location = /50x.html {
                 root /usr/share/nginx/www;
         }        
         location ~ /\.ht {
                 allow all;
         }
}

Then finally I restart nginx and run this:

sudo uwsgi -s /tmp/uwsgi.sock --module myapp --callable app And this is the output

*** Starting uWSGI 1.4.3 (64bit) on [Mon Dec 10 15:41:00 2012] ***
compiled with version: 4.6.3 on 10 December 2012 13:06:15
os: Linux-3.2.0-32-generic #51-Ubuntu SMP Wed Sep 26 21:33:09 UTC 2012
nodename: jeremylspencer.com
machine: x86_64
clock source: unix
detected number of CPU cores: 2
current working directory: /home/admin.jeremylspencer.com
detected binary path: /usr/local/bin/uwsgi
uWSGI running as root, you can use --uid/--gid/--chroot options
*** WARNING: you are running uWSGI as root !!! (use the --uid flag) *** 
*** WARNING: you are running uWSGI without its master process manager ***
your processes number limit is 31285
your memory page size is 4096 bytes
detected max file descriptor number: 1024
lock engine: pthread robust mutexes
uwsgi socket 0 bound to UNIX address /tmp/uwsgi.sock fd 3
Python version: 2.7.3 (default, Aug  1 2012, 05:25:23)  [GCC 4.6.3]
*** Python threads support is disabled. You can enable it with --enable-threads ***
Python main interpreter initialized at 0x1dfa790
your server socket listen backlog is limited to 100 connections
mapped 72392 bytes (70 KB) for 1 cores
*** Operational MODE: single process ***
WSGI app 0 (mountpoint='') ready in 0 seconds on interpreter 0x1dfa790 pid: 13645 (default app)
*** uWSGI is running in multiple interpreter mode ***
spawned uWSGI worker 1 (and the only) (pid: 13645, cores: 1)

But yet all I get is a 502 error... any how can i fix this?

Answer 1

unix sockets are filesystem objects, so nginx need write permissions to /tmp/uwsgi.sock

You are running uWSGI as root (why ???) so /tmp/uwsgi.sock will be owned by root while nginx generally runs as nobody or www-data.

If you do not want to take in account permissions just use TCP sockets, but obviously do not run your app as root.

Answer 2

You can have a look on this: Python flask with Nginx and uWSGI as the repo provides the exact case / scenario on how to use Flask in production mode.