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.

Install a Python application

Pre-installation settings

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.

Install the application

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.

Test the application

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

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

Restart the application

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