Flask on Apache with mod_wsgi

WSGI Application wrapper

Many Flask applications are developed in a virtualenv to keep dependencies for each application separate from the system-wide Python installation. Make sure that mod-wsgi is installed in your virtualenv:

pip install mod-wsgi

Then create a wsgi wrapper for your Flask application. Usually it’s kept in the root directory of your application.

my-application.wsgi

activate_this = '/path/to/my-application/venv/bin/activate_this.py'
execfile(activate_this, dict(__file__=activate_this))
import sys
sys.path.insert(0, '/path/to/my-application')

from app import app as application

This wrapper activates the virtual environment and all of its installed modules and dependencies when run from Apache, and makes sure the application path is first in the search paths. By convention, WSGI application objects are called application.

Apache sites-enabled configuration for WSGI

The advantage of using Apache over the builtin werkzeug server is that Apache is multi-threaded, meaning that multiple connections to the application can be made simultaneously. This is especially useful in applications that make use of XmlHttpRequest (AJAX) on the front-end.

/etc/apache2/sites-available/050-my-application.conf (or default apache configuration if not hosted on a shared webserver)

<VirtualHost *:80>
        ServerName my-application.org

        ServerAdmin admin@my-application.org

        # Must be set, but can be anything unless you want to serve static files
        DocumentRoot /var/www/html

        # Logs for your application will go to the directory as specified:

        ErrorLog ${APACHE_LOG_DIR}/error.log
        CustomLog ${APACHE_LOG_DIR}/access.log combined

        # WSGI applications run as a daemon process, and need a specified user, group
        # and an allocated number of thread workers. This will determine the number
        # of simultaneous connections available.
        WSGIDaemonProcess my-application user=username group=username threads=12
        
        # The WSGIScriptAlias should redirect / to your application wrapper:
        WSGIScriptAlias / /path/to/my-application/my-application.wsgi
        # and set up Directory access permissions for the application:
        <Directory /path/to/my-application>
                WSGIProcessGroup my-application
                WSGIApplicationGroup %{GLOBAL}
                
                AllowOverride none
                Require all granted
        </Directory>
</VirtualHost>