Access from other than localhost

[lukeer]

Hi forum,

there's a python-flask-socket.io program which runs a web server I can access from localhost by opening Firefox at the page http://localhost:5000
While that is great, it's not enought for the problem at hand. The server needs to be accessible from the whole LAN. But trying to access it from the very computer it runs on via the address http://192.168.1.42:5000 (that's the IP address of my development machine running the server) results in Firefox telling me that the connection failed. Maybe the site is down, I shall try it later. And I should check my internet settings. And I should check the firewall.

I created a Windows Defender Firewall inbound rule and I also tried to completely switch off the firewall.
I tried running the program with added host and cors_allowed_origins parameters:

    socketio.run(app, host='0.0.0.0:5000', cors_allowed_origins='*')

But the error remains the same.

What do I need to do in order to reach the web server from other clients than localhost?

[Edit]
We can be sure now that the surrounding system works. I startet
$ winpty python -m http.server 5000
and got a working web server that is reachable both from the development machine itself and from android phones sharing the same LAN. So now I definitely need to know what could possibly go wrong with socketio.run() to check with my problem at hand.
[/Edit]

[lukeer]

Working on this on windows in Visual Studio Code. Nearly a year after above question, I finally found the solution to it:
Make sure that the socketio.run() call actually gets executed.

For reasons I don't remember now, I was used to start the application this way:

winpty python -m app.py

And since the socketio.run() call is enclosed in python's

if __name__ == "__main__":
   ...

It is not executed. The web server still worked since Flask does some magic on its own. Changing the call to

winpty python app.py

did the trick.

2nd problem: Get this to work in a debugging environment.
Here, the name check fails again because Visual Studio Code calls something called "launcher" with a bunch of arguments and then our application starts and we can use all the beautiful debugging capabilities of VSC.
Want to be able to debug and have connections from remote machines at the same time? That's possible by editing a file $ProjectFolder$/.vscode/launch.json which contains a json-formatted configuration. There's a list in it configurations[0].args[] which contains some arguments that the application under debug is started with:

{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Python: Flask",
            "type": "python",
            "request": "launch",
            "module": "flask",
            "env": {
                "FLASK_APP": "app.py",
                "FLASK_ENV": "development",
                "FLASK_DEBUG": "0"
            },
            "args": [
                "run",
//                "--no-debugger"
                "--host=0.0.0.0",
                "--port=80"
            ],
            "justMyCode": false,
            "jinja": true
        }
    ]
}

This one worked for me (I added the two lines after the single commented-out one).