Scroll down to and examine the configuration, which is named "Python: Flask". This configuration contains "module": "flask",, which tells VS Code to run Python with -m flask when it starts the debugger. It also defines the FLASK_APP environment variable in the env property to identify the startup file, which is app.py by default, but allows you to easily specify a different file. If you want to change the host and/or port, you can use the args array.