How to Install a Python WSGI Application

This article describes how to install a Python™ WSGI web application on the command line.

Python WSGI is a standardized web interface that runs Python applications.

If you need more information, please read the Python WSGI documentation.

Before you start, make sure your hosting provider has installed the following EasyApache 4 packages on your server:

• mod-passenger
  This module disables Apache’s mod_userdir module.
• mod-env
  We also recommend that your hosting provider install the  module ea-ruby27-ruby-devel

Also, your hosting provider must install the following packages:

• python-flask (or another framework)
  We strongly recommend that you use a framework with Python WSGI.
• pip
  The package name depends on your version of Python.

Please follow these steps to install an application:

1. Log in to the server via SSH as a cPanel user.
2. Create an application directory relative to your home directory. Run the following command, where directoryname is the application directory:

   mkdir directoryname

3. Change to the application’s directory. Run the following command, where directoryname is the application directory:

   cd directoryname

4. Copy this application to your server.
5. Create a passenger_wsgi.py file. Where pythonapp is your Python application and MyApp is the application function:

   echo "from pythonapp import MyApp as application" > passenger_wsgi.py

6. Install application dependencies. Create a pip requirements.txt file, after that run the following command:

   pip install –user -r requirements.txt

   Note: Any dependencies also can install in the Ensure Dependencies section of cPanel’s Application Manager interface (cPanel » Home » Software » Application Manager).
   Warning:

   • The version requirements of your dependency must match your version of Python. For example, a dependency that requires Python 2 or earlier will not work in an application that you run with Python 3.
   • Some dependencies will change what your application requires to work. For example, Flask’s render_template dependency requires that you keep your index.html file in a templates folder.

After installing the application, make sure that it is active.

1. Run this command:

   python pythonapp.py

   The output may resemble the following example:

   
2. Open another terminal window and log in to the server via SSH as the same cPanel user.
3. Run this command:

   curl http://localhost:5000 

   The output will be similar to the following example:

   Hello, World!

Register the application after installing it. For this, use cPanel’s Application Manager interface (cPanel » Home » Software » Application Manager).

Then you can access the application in a web browser with the following URL:

http://example.com/pythonapp

To restart the application after editing it, create the restart.txt touch file. Create this file in the /tmp directory of the application. This file directs Phusion Passenger® to restart the application after changing it. This action applies your changes to the application