pytune.com - Local dev with Nginx and uWSGI

This article is based on https://github.com/Einsteinish/PyTune.git

In the previous article (pytune.com - Local dev with Apache mod_wsgi), we were able to run our Django app for pytune.com using mod_wsgi and Apache. In this page, we'll run the app with uWSGI and Nginx.

uWSGI is an application container server coded in pure C. It operates on a client-server model, and our Web server (e.g., nginx, Apache) communicates with a django-uwsgi "worker" process to serve dynamic content.

Install uWSGI:

(venv)k@laptop:/var/www/django/pytune4$ sudo pip install uwsgi

Our wsgi.py looks like this:

import os
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "settings")

from django.core.wsgi import get_wsgi_application
application = get_wsgi_application()

uWSGI config file is pytune4-app.ini which creates isolated environments, each running their own versions of packages.

[uwsgi]
module = wsgi:application

master = true
processes = 5

socket = pytune4-app.sock
chmod-socket = 664
vacuum = true

die-on-term = true

We can use the ini configuration file by the following command:

(venv)k@laptop:/var/www/django/pytune4$ sudo uwsgi --ini pytune4-app.ini

[uWSGI] getting INI configuration from pytune4-app.ini
*** Starting uWSGI 2.0.13.1 (64bit) on [Wed May 25 14:12:03 2016] ***
compiled with version: 4.8.4 on 25 May 2016 10:25:54
os: Linux-3.13.0-40-generic #69-Ubuntu SMP Thu Nov 13 17:53:56 UTC 2014
nodename: laptop
machine: x86_64
clock source: unix
pcre jit disabled
detected number of CPU cores: 2
current working directory: /var/www/django/pytune4
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) *** 
your processes number limit is 27820
your memory page size is 4096 bytes
detected max file descriptor number: 1024
lock engine: pthread robust mutexes
thunder lock: disabled (you can enable it with --thunder-lock)
uwsgi socket 0 bound to UNIX address pytune4-app.sock fd 3
Python version: 2.7.6 (default, Jun 22 2015, 18:01:27)  [GCC 4.8.2]
*** Python threads support is disabled. You can enable it with --enable-threads ***
Python main interpreter initialized at 0x1564ab0
your server socket listen backlog is limited to 100 connections
your mercy for graceful operations on workers is 60 seconds
mapped 436608 bytes (426 KB) for 5 cores
*** Operational MODE: preforking ***
WSGI app 0 (mountpoint='') ready in 2 seconds on interpreter 0x1564ab0 pid: 9785 (default app)
*** uWSGI is running in multiple interpreter mode ***
spawned uWSGI master process (pid: 9785)
spawned uWSGI worker 1 (pid: 9786, cores: 1)
spawned uWSGI worker 2 (pid: 9787, cores: 1)
spawned uWSGI worker 3 (pid: 9788, cores: 1)
spawned uWSGI worker 4 (pid: 9789, cores: 1)
spawned uWSGI worker 5 (pid: 9790, cores: 1)

Check the process:

$ ps -ef |grep pytune4-app
root      9784 21033  0 14:12 pts/35   00:00:00 sudo uwsgi --ini pytune4-app.ini
root      9785  9784  0 14:12 pts/35   00:00:01 uwsgi --ini pytune4-app.ini
root      9786  9785  0 14:12 pts/35   00:00:00 uwsgi --ini pytune4-app.ini
root      9787  9785  0 14:12 pts/35   00:00:00 uwsgi --ini pytune4-app.ini
root      9788  9785  0 14:12 pts/35   00:00:00 uwsgi --ini pytune4-app.ini
root      9789  9785  0 14:12 pts/35   00:00:00 uwsgi --ini pytune4-app.ini
root      9790  9785  0 14:12 pts/35   00:00:00 uwsgi --ini pytune4-app.ini

For more information about the ini file, please visit How to use Django with uWSGI.

Let's see what's new in our project directory:

$ ls -la /var/www/django/pytune4
...
-rw-r--r--  1 root     root       143 May 25 13:53 pytune4-app.ini
srw-rw-r--  1 www-data www-data     0 May 25 14:12 pytune4-app.sock
...

Note that we made changes to uid and gid from 'root' to 'www-data'.

We want to launch a uWSGI instance at boot so that our application is always available (/etc/init/pytune4-app.conf):

description "uWSGI instance to serve pytune4-app"

start on runlevel [2345]
stop on runlevel [!2345]

setuid root
setgid www-data

script
    cd /var/www/django/pytune4
    . venv/bin/activate
    uwsgi --ini pytune4-app.ini
end script

Now that our Upstart script is complete, we can start the service:

(venv)$ sudo start pytune4-app
$ ps -ef|grep pytune4-app
root     13238 13234  8 16:07 ?        00:00:01 uwsgi --ini pytune4-app.ini
root     13239 13238  0 16:07 ?        00:00:00 uwsgi --ini pytune4-app.ini
root     13240 13238  0 16:07 ?        00:00:00 uwsgi --ini pytune4-app.ini
root     13241 13238  0 16:07 ?        00:00:00 uwsgi --ini pytune4-app.ini
root     13242 13238  0 16:07 ?        00:00:00 uwsgi --ini pytune4-app.ini
root     13243 13238  0 16:07 ?        00:00:00 uwsgi --ini pytune4-app.ini

The app will start automatically on boot.

We can stop the service at any time by typing:

(venv)$ sudo stop pytune4-app

Let's create a new file /etc/nginx/sites-available/pytune.com.conf:

server {
    listen 80;
    server_name pytune.com www.pytune.com;

    location / {
        include         uwsgi_params;
        uwsgi_pass      unix:/var/www/django/pytune4/pytune4-app.sock;
    }
}

Enable the server configuration we just made by linking it to the sites-enabled directory:

$ sudo ln -s /etc/nginx/sites-available/pytune.com.conf /etc/nginx/sites-enabled

Check the configuration file for any syntax errors:

$ sudo service nginx configtest
 * Testing nginx configuration

If it reports back that no problems were detected, restart the server to implement new changes:

$ sudo service nginx restart

Once Nginx restarts, we should be able to go to our server's domain name or IP address (without a port number) and see the application we configured: