How to setup Python flask application on shared hosting

In this tutorial I will show you how to setup a Python Flask application that starts by passenger

Step 1: Create a place to house your files & set correct document root

If you want you can use your main domain. However in this case I will use a subdomain where I will run my application.

First Navigate to Web > Subdomains and enter the subdomain of your preference.

For the next step we’ll want to head on over to the terminal. You may access it via Dev > Terminal or via SSH by using the login details sent to you in the “Get started with your web host” email.

Once there we’ll first create the correct document root.

mkdir /var/www/python.flask.3li.se/public

Make sure to replace python.flask.3li.se with the subdomain that you created

Next we’ll go back to the control panel and update the document root to reflect the change. Navigate to Web > Subdomains again and in the top left corner click Change Mode: List Subdomains

From there change the document root to the /public directory you just created like so

Step 2: install a python version of your choice

From now on we’ll only work in the terminal.

First find out what python version you’d like to use. In my case I chose 3.10 but you can choose any version you like.

Run the following command to install the python version

pyenv install 3.10

It can take a few minutes for it to compile and install python.

Step 3: create all the necessary files.

First navigate one level below the document root of your site.

cd /var/www/python.flask.3li.se

Next specify the python version you’d like to use

pyenv local 3.10

Step 4: Install flask and create the passenger file

To install flask run the following command

pip3 install flask

Create a Passenger startup file to run Flask as a Python WSGI application:

touch passenger_wsgi.py

Edit the file with the editor of your choice and make sure it has the following content:

from flask import Flask
application = Flask(__name__)
 
@application.route("/")
def hello():
 return "Hello World!"

if __name__ == "__main__":
 application.run()

Step 5: Create the .htaccess file to start passenger

The last thing to do is to create the .htaccess file that will start passenger.

First navigate to your document root and create a file called .htaccess

cd /var/www/python.flask.3li.se/public && touch .htaccess

Next edit the file with the editor of your choice and make sure it has the following content:

PassengerAppRoot /var/www/python.flask.3li.se
PassengerPython /usr/local/share/python/pyenv/shims/python
PassengerEnabled on

Remember to replace python.flask.3li.se with your subdomain.

The last thing to do is delete the template index.html file that was generated.

rm /var/www/python.flask.3li.se/public/index.html

That’s it. We’re done. You can now visit your site and you should see Hello World!