How to Install a Python WSGI Application


Last modified: February 22, 2024

Overview

This document describes how to install a Python™ WSGI web application on the command line. Python WSGI is a standardized web interface that allows you to run Python applications.

Warning:
  • Because WebPros International, LLC doesn’t develop or ship Python WSGI web applications, cPanel Technical Support can’t help you with them.
  • We are not responsible for any data loss.
Note:
  • We recommend that you perform the steps in this document via the command line as a cPanel user unless the step specifies otherwise.
  • You can also perform these steps in cPanel’s Terminal interface (cPanel » Home » Advanced » Terminal).
  • In this document, pythonapp represents the application’s name.

For more information, read the Python WSGI documentation.

Install a Python application

Pre-installation settings

Before you begin, make certain that your hosting provider installed the following EasyApache 4 packages on your server:

  • mod-passenger

    Note:

    This module disables Apache’s mod_userdir module.

  • mod-env

    Note:

    We also recommend that your hosting provider install the ea-ruby27-ruby-devel module.

Additionally, your hosting provider must install pip.

Note:

The package name will vary depending on your Python version.

We also strongly recommend that you install and use a framework with Python WSGI. For example, you may use pip to install Python Flask.

Install the application

To install an application, perform the following steps:

  1. Log in to the server via SSH as a cPanel user.
  2. Create the application’s directory, relative to your home directory. To do this, run the following command, where directoryname represents the application’s directory:
    mkdir directoryname
  3. Change to the application’s directory. To do this, run the following command, where directoryname represents the application’s directory:
    cd directoryname
  4. Copy the application to your server.
  5. Create the passenger_wsgi.py file. In this example, pythonapp represents your python application and MyApp represents an application function:
    echo "from pythonapp import MyApp as application" > passenger_wsgi.py
  6. Install the application’s dependencies. To do this, create a pip requirements.txt file, then run the following command:
    pip install –user -r requirements.txt
    Note:

    You can also install any dependencies in the Ensure Dependencies section of cPanel’s Application Manager interface (cPanel » Home » Software » Application Manager).

    Warning:
    • Your dependency version requirements must match your Python version. For example, a dependency that requires Python 2 or earlier will not work on 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 you install the application, we recommend that you confirm that it’s active.

  1. Run the following command:
    python pythonapp.py
    The output might resemble the following example:
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    <!DOCTYPE html>
              <section class="main">
                <h1>Hello world!</h1>
                Welcome to the example app.
              </section>
            </body>
            </html>
    	
  2. Open another terminal window and log in to the server via SSH as the same cPanel user.
  3. Run the following command:
    curl http://localhost:5000 
    The output will resemble the following example:
    Hello, World!

Register the application

After you install the application, register it. To do this, use cPanel’s Application Manager interface (cPanel » Home » Software » Application Manager).

You can then access the application in a web browser with the following URL:

http://example.com/pythonapp

Restart the application

To restart your application after you edit it, create the restart.txt touch file. Create this file in the application’s /tmp directory. This file directs Phusion Passenger® to restart the application after you modify it. This action applies your changes to the application.

Important:

Phusion Passenger will only restart the application if you touch the restart.txt touch file.

Additional Documentation