Flask is a lightweight python framework used to build web applications. We’ll also look at how to build the back-end of our web application and deploy it on your machine inside a Docker container.

To run a flask app, either we need to use flask command or python's -m switch with flask. But, before that we need to export a variable called FLASK_APP to specify how to load the application. Note: This will start a development web server. But, for production deployment, you need to use production-ready web server like uWSGI

To run a Flask application, you can either use the 'flask run' command or Python's -m switch with Flask. Before doing that, you need to tell your terminal which application to work with by exporting the FLASK_APP environment variable to your script. From the above link itself, you have to set the FLASK_APP environment variable to your script.

See issue 135. Default FlaskUI class parameters: Develop your app as you would normally do, add flaskwebgui at the end or for tests. flaskwebgui doesn't interfere with your way of doing an application it just helps "converting" it into a desktop app more easily with pyinstaller or pyvan.