Disable ability for Flask to display warning about using a development server in a production environment.

Prevent_flask_production_environment_warning.py

"""
  Flask will display a warning everytime you startup your application if you are not using it in behind a separate WSGI server.
  
   * Environment: production
   WARNING: Do not use the development server in a production environment.
   Use a production WSGI server instead.
  
  This was not relevant for my scenario and I wanted the message gone, 
   so using this method will remove their ability to print that message
   
   This method replaces the function they use to write the banner with a no-op. 
   Be aware that this prevents the rest of the Flask startup banner from displaying as well.
   The only output you will see from the method below is:
    * Running on http://0.0.0.0:80/ (Press CTRL+C to quit)

"""

from flask import Flask
import sys
cli = sys.modules['flask.cli']
cli.show_server_banner = lambda *x: None

app = Flask(__name__)
app.run(host='0.0.0.0', port='80')

from flask import cli
cli.show_server_banner = lambda *_: None

Another way:

import os
os.environ["WERKZEUG_RUN_MAIN"] = "true"
app.run(...)

@bw2's solution worked for me. Cheers!

Yet another way (work for versions >2.1.x):

def _ansi_style_supressor(func: Callable[..., Any]) -> Callable[..., Any]:
    @functools.wraps(func)
    def wrapper(*args: Tuple[Any, ...], **kwargs: Dict[str, Any]) -> Any:
        if args and isinstance(args[0], str) and args[0].startswith('WARNING: This is a development server.'):
            return ''
        return func(*args, **kwargs)

    return wrapper

...

werkzeug.serving._ansi_style = _ansi_style_supressor(werkzeug.serving._ansi_style)

cli.show_server_banner = lambda *_: None

that works for me