Failed connection when running flask app on Linux server

Question

I'm trying to deploy a flask app on a linux server. Currently, I'm testing it I'm try to run it with the following commands.

export FLASK_APP=main.py

flask run --host=0.0.0.0

When I run this and try to navigate to [SERVER IP]:5000, there is a failed connection to the server. I've tried to implement solutions I've found elsewhere such as here:Can't connect to Flask web service, connection refused

I've made these changes and it still does not work:

if __name__ == '__main__':
    app.run(host='0.0.0.0',port=5000)

sudo ufw allow 5000

Some information about the server - Through linode running Ubuntu 21.04

Any help would be greatly appreciated.

Can you connect to it locally telnet 127.0.0.1 5000 , (or curl) , if its working then try to find out why external connection not going through, may be firewall issue/ routing issue? — Tharanga Abeyseela
– Tharanga Abeyseela, Commented Sep 7, 2021 at 22:36
It does work locally. Again, I mentioned in the question that I enabled port 5000, so I assumed that that would resolve any firewall issues — leaf
– leaf, Commented Sep 7, 2021 at 23:09
Are you connect via a proxy ? can you telnet telnet serverip 5000 from another server ? ping from another server to your flask app server ip and check the connectivity. — Tharanga Abeyseela
– Tharanga Abeyseela, Commented Sep 8, 2021 at 22:29

user16855370 · Accepted Answer · 2021-09-07 23:28:28Z

2

You should execute main.py directly if you're using __name__ == "__main__"

if __name__ == '__main__':
    app.run(host='0.0.0.0',port=5000)

Your app.run() call isn't executed when using flask run

It should run on port 5000 by default so there shouldn't be any need for that configuration.

Try python3 main.py as suggest above and share the outcome.

answered Sep 7, 2021 at 23:28

user16855370

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Comments

Ali Gökkaya · Accepted Answer · 2021-09-07 22:33:07Z

1

Can you try to run it as python main.py from the terminal?

or

python3 main.py

answered Sep 7, 2021 at 22:33

Ali Gökkaya

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