无法使用Flask托管Web服务器

Question

When I run this sample code :

from flask import Flask

app = Flask(__name__)

def main () :
    return "Welcome to Flask "

if __name__ ==  "__main__":
    app.run(debug=True, host="0.0.0.0", port=80)

Entering following on the terminal: python3 app.py , the output is:

 * Serving Flask app "app" (lazy loading)
 * Environment: production
   WARNING: Do not use the development server in a production 
   environment.
   Use a production WSGI server instead.
 * Debug mode: on
 * Running on http://0.0.0.0:80/ (Press CTRL+C to quit)
 * Restarting with stat
 * Debugger is active!
 * Debugger PIN: 144-032-769
 127.0.0.1 - - [13/Jun/2018 00:11:59] "GET / HTTP/1.1" 404 -
 127.0.0.1 - - [13/Jun/2018 00:11:59] "GET /favicon.ico HTTP/1.1" 404 
 -
 127.0.0.1 - - [13/Jun/2018 00:12:15] "GET / HTTP/1.1" 404 -
 127.0.0.1 - - [13/Jun/2018 00:12:16] "GET /favicon.ico HTTP/1.1" 404 -
 127.0.0.1 - - [13/Jun/2018 00:12:22] "GET / HTTP/1.1" 404 -
 127.0.0.1 - - [13/Jun/2018 00:12:22] "GET /favicon.ico HTTP/1.1" 404 -

It does not stop

And when I open 127.0.0.1 in my browser it says that Not Found

Answer 1

you have not given main() a route decorator. your function should look like this:

@app.route('/')
def main():
    return "Welcome to Flask "