How to Install a Python WSGI Application

Last modified: February 6, 2023

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 cPanel, L.L.C. 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.

Your hosting provider must also install the following packages:

python-flask (or another framework)

Note:

We strongly recommend that you use a framework with Python WSGI.
pip

Note:

The package name will vary depending on your Python version.

Install the application

To install an application, perform the following steps:

Log in to the server via SSH as a cPanel user.
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
```
Change to the application’s directory. To do this, run the following command, where directoryname represents the application’s directory:
```
cd directoryname
```
Copy the application to your server.
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
```
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.

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>
	

Open another terminal window and log in to the server via SSH as the same cPanel user.
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.