i've build a simple flask app on my google cloud GCE instance, but i can't access it from another computer, here's the simple flask app that i've build :
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', port=5000)
and when i run the app
and access the external IP of my machine it only said this site can't be reached 
i have set up a new firewall rule 
but it still not working.
