Unable to reach a python flask-enabled web server on gce

Question

I am running a very simple http server on a VM in GCE.

The code is very simple

from flask import Flask, render_template, request, json, abort

app = Flask(__name__)
@app.route('/', methods=['GET'])
def heartbeat():
  return 'hello'

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

I can reach the '/' on the server using lynx locally

I did not modify any firewall rules. Here is part of the rules:

Here is part of the VM information that is relevant to the networking

You can see http traffic is allowed.

However when I tried to connect to the server from my PC, the connection t

score 5 · Accepted Answer · answered Feb 08 '17 at 09:19

5

By default python flask is listening to port 5000. I need a firewall rule to allow the traffic to go through

answered Feb 08 '17 at 09:19

Anthony Kong

3,288
11
57
96

That's correct. I ran into same problem and found the firewall in my PC is blocking 5000 outgoing - another thing that worth to check! – Deqing Nov 28 '17 at 04:56

score 3 · Answer 2 · answered Apr 19 '18 at 22:50

3

You need to create a firewall rule that allows traffic to that port. In the google cloud console on your browser go to Menu -> VPC Network -> Firewall Rules. Here is a template of the rule you should create. This rule allows any traffic on any of your ports.

answered Apr 19 '18 at 22:50

Hemanth Kondapalli

131
1

This is exactly what I wanted. I deployed Flask App on GCP Virtual machine – Rohit Singh Aug 11 '20 at 00:36

score -1 · Answer 3 · answered Feb 09 '17 at 11:25

-1

You can also run your app on port 80 by slightly changing your last line to:

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

answered Feb 09 '17 at 11:25

Alex Palcuie

274
1
4

It's suggested that [not to use port 80 for flask app](https://stackoverflow.com/questions/33086555/why-shouldnt-flask-be-deployed-with-the-built-in-server) – Deqing Nov 28 '17 at 03:59

Unable to reach a python flask-enabled web server on gce

3 Answers3