Apache and mod_wsgi on Ubuntu 12.04 (Precise Pangolin)
Updated by Linode
The WSGI specification provides a standard and efficient method for dynamic web applications to communicate with web servers.
mod_wsgi provides a method for simply deploying WSGI applications with Apache. WSGI is used to deploy applications written with frameworks and tools like Django, Web.py, Werkzug, Chery.py, TurboGears, and Flask. These guides outline this installation and configuration process for deploying WSGI applications.
Set the Hostname
Before you begin installing and configuring the components described in this guide, please make sure you’ve followed our instructions for setting your hostname. Issue the following commands to make sure it is set properly:
hostname hostname -f
The first command should show your short hostname, and the second should show your fully qualified domain name (FQDN).
Issue the following commands to ensure that your system’s package repositories and installed programs are up to date and that all required software is installed:
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apt-get update apt-get upgrade apt-get install apache2 python-setuptools libapache2-mod-wsgi
Your application may require additional dependencies. Install these either using the Ubuntu package tools or by using the
easy_install command included in
python-setuptools before proceeding.
Configure WSGI Handler
In order for
mod_wsgi to be able to provide access to your application, you will need to create a
application.wsgi file inside of your application directory. The application directory should be located outside of your
DocumentRoot. The following three sections each present a different
application.wsgi example file to illustrate the basic structure of this file:
Basic Hello World WSGI Configuration
In this example, the application is stored in
/var/www/example.com/application directory. Modify this example and all following examples to conform to the actual files and locations used in your deployment.
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import os import sys sys.path.append('/var/www/example.com/application') os.environ['PYTHON_EGG_CACHE'] = '/var/www/example.com/.python-egg' def application(environ, start_response): status = '200 OK' output = 'Hello World!' response_headers = [('Content-type', 'text/plain'), ('Content-Length', str(len(output)))] start_response(status, response_headers) return [output]
You must append the path of your application to the system path as above. The declaration of the
PYTHON_EGG_CACHE variable is optional but may be required for some applications when WSGI scripts are executed with the permissions of the web server. The WSGI application must be callable as
application, regardless of how the application code is structured.
Web.py WSGI Configuration
Consider the following example Web.py application which is embedded in a
application.wsgi file. The Web.py Framework must be installed in order for the following application to run successfully.
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import web urls = ( '/(.*)', 'hello' ) class hello: def GET(self, name): if not name: name = 'World' return 'Hello, ' + name + '!' if __name__ == "__main__": app.run() app = web.application(urls, globals(), autoreload=False) application = app.wsgifunc()
Django WSGI Configuration
Consider the following example
application.wsgi file for Django applications:
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import os import sys sys.path.append('/var/www/example.com/application') os.environ['PYTHON_EGG_CACHE'] = '/var/www/example.com/.python-egg' os.environ['DJANGO_SETTINGS_MODULE'] = 'settings' import django.core.handlers.wsgi application = django.core.handlers.wsgi.WSGIHandler()
Django must be installed on your system and a working Django application before this example will function. The
DJANGO_SETTINGS_MODULE points to the “
settings.py file for your application, which would be located in the “
/var/www/example.com/application/settings.py in the case of this example.
Deploy the following
VirtualHost configuration and modify the paths and domains to reflect the requirements of your application:
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<VirtualHost *:80> ServerName example.com ServerAlias www.example.com ServerAdmin firstname.lastname@example.org DocumentRoot /var/www/example.com/public_html ErrorLog /var/www/example.com/logs/error.log CustomLog /var/www/example.com/logs/access.log combined WSGIScriptAlias / /var/www/example.com/application/application.wsgi Alias /robots.txt /var/www/example.com/public_html/robots.txt Alias /favicon.ico /var/www/example.com/public_html/favicon.ico Alias /images /var/www/example.com/public_html/images Alias /static /var/www/example.com/public_html/static </VirtualHost>
In this example, the
WSGIScriptAlias directive tells Apache that for this
VirtualHost, all requests below
/ should be handled by the WSGI script specified. The series of four
Alias directives allow Apache to serve the
favicon.ico files as well as all resources beneath the
/static locations, directly from the
DocumentRoot without engaging the WSGI application. You can add as many
Alias directives as you require.
When you have configured your Apache
VirtualHost, issue the following command to restart the web server:
service apache2 restart
You will need to restart the web server every time the
application.wsgi file changes. However, all other modifications to your application do not require a web server restart. Congratulations! You have now successfully deployed a WSGI application using
You may wish to consult the following resources for additional information on this topic. While these are provided in the hope that they will be useful, please note that we cannot vouch for the accuracy or timeliness of externally hosted materials.
- A Basic “Hello World” Django Application
- Deploy Django Applications with mod_wsgi
- Deploy Web.py Applications with mod_wsgi
- Flask Framework
This guide is published under a CC BY-ND 3.0 license.