Hosting Django under Nginx with SCGI and WSGI

Description of mod_wsgi and mod_scgi currently developed for Nginx server.

Info

A module called mod_wsgi is currently developed for Nginx (0.5 series supported currently). Latest news we will find on Nginx wiki. To install this module you have to

Get the latest code (mercurial RCS):
hg clone http://hg.mperillo.ath.cx/nginx/mod_wsgi/
Compile nginx adding --add-module=/ścieżka/do/mod_wsgi/ to configure, for example:
./configure --add-module=/ścieżka/do/mod_wsgi/
After compile and install you are ready to go.

Here is a part of nginx.conf for hosting Django (Django-SVN) project using mod_wsgi:

server { 
	listen       8000;
	server_name  localhost;
	
	wsgi_var  REQUEST_METHOD      $request_method;
	#wsgi_var  SCRIPT_NAME         $uri; # TODO
	#wsgi_var  PATH_INFO           $uri; # TODO
	wsgi_var  QUERY_STRING        $query_string;
	
	wsgi_var  CONTENT_TYPE        $content_type;
	wsgi_var  CONTENT_LENGTH      $content_length;
	
	wsgi_var  SERVER_NAME         $server_name;
	wsgi_var  SERVER_PORT         $server_port;
	
	wsgi_var  SERVER_PROTOCOL     $server_protocol;
	
	#
	# additional variables
	# (they will be present in the WSGI environment only if not empty)
	#
	wsgi_var  REQUEST_URI         $request_uri;
	wsgi_var  DOCUMENT_URI        $document_uri;
	wsgi_var  DOCUMENT_ROOT       $document_root;
	
	wsgi_var  SERVER_SOFTWARE     $nginx_version;
	
	wsgi_var  REMOTE_ADDR         $remote_addr;
	wsgi_var  REMOTE_PORT         $remote_port;
	wsgi_var  SERVER_ADDR         $server_addr;
	
	
	wsgi_var REMOTE_USER $remote_user;
	
	
	#wsgi_middleware  wsgiref.validate  validator;
	#wsgi_middleware  paste.lint;

	location  / {
		#client_body_buffer_size 50;
		wsgi_pass /path/to/wsgi.py;

		wsgi_pass_authorization off;
		wsgi_script_reloading on;
		wsgi_use_main_interpreter on;
		}
	}

We have to set a path to wsgi.py file, which is located in the project folder (for example) and has the code:

import os, sys
sys.path.append('/path/to/django/project/')

os.environ['DJANGO_SETTINGS_MODULE'] = 'settings'
import django.core.handlers.wsgi
application = django.core.handlers.wsgi.WSGIHandler()

If paths are correct is should work (localhost:8000 in this example)

SCGI

mod_scgi is a second module from the same developer, also in development. It does not handle full SCGI specs, so using it to host Django is currently a bit limited. Installation is very similar to the mod_wsgi install. Config looks like this:

location  / {
	## scgi_var  CONTENT_LENGTH     $content_length;
	scgi_var  QUERY_STRING       $query_string;
	scgi_var  REQUEST_METHOD     $request_method;
	scgi_var  CONTENT_TYPE       $content_type;
	
	## scgi_var  SCRIPT_NAME        $fastcgi_script_name;
	scgi_var  REQUEST_URI        $request_uri;
	scgi_var  DOCUMENT_URI       $document_uri;
	scgi_var  DOCUMENT_ROOT      $document_root;
	scgi_var  SERVER_PROTOCOL    $server_protocol;
	
	scgi_var  SCGI               1;
	scgi_var  SERVER_SOFTWARE    nginx/$nginx_version;
	
	scgi_var  REMOTE_ADDR        $remote_addr;
	scgi_var  REMOTE_PORT        $remote_port;
	scgi_var  SERVER_ADDR        $server_addr;
	scgi_var  SERVER_PORT        $server_port;
	scgi_var  SERVER_NAME        $server_name;
	scgi_pass   127.0.0.1:8080;
	scgi_var    SCRIPT_NAME  $uri;
	scgi_var    PATH_INFO    $uri;
	}

Most important is scgi_pass 127.0.0.1:8080; - on that IP/Port a WSGI/SCGI server has to listen. For django we have django-scgi.py, which we be run like this:

python django-scgi.py --projects=/path/to/Django/project/ --settings=settings --host=localhost --port=8080

Django will return the page from the Django project, but it will look like text/plain and not as text/html:

Status: 200 OK
Vary: Cookie
Content-Type: text/html; charset=utf-8

Currently mod_scgi needs first line to look like:

HTTP/1.1 200 OK

So to use it some flup editing is required I guess ;)

RkBlog

22 July 2008; Piotr Maliński