running flask from another port code example

Example 1: flask port

from flask import Flask

app = Flask(__name__)

if __name__ == '__main__':
      app.run(port=80)

# Also make sure that nothing else is running on port 80

Example 2: how to run flask in port 80

sudo apt install authbind
sudo touch /etc/authbind/byport/80
sudo chmod 777 /etc/authbind/byport/80
authbind --deep python3 app.py