Kubernetes Istio Gateway & VirtualService Config Flask Example - flask

Question

I try to get some hands on experience with K8s & istio. I am using minikube and I try to deploy a dummy flask web-app. However, for some reason I do not manage to get the istio routing working.
E.g.
curl -v -H 'Host: hello.com' 'http://127.0.0.1/' --> 503 Service Unavailable
Do you see any issue in my specs?
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
name: flask-gateway
spec:
selector:
istio: ingressgateway
servers:
- port:
number: 80
name: http
protocol: HTTP
hosts:
- "hello.com"
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
name: flaskvirtualservice
spec:
hosts:
- "hello.com"
gateways:
- flask-gateway
http:
- route:
- destination:
host: flask.default.svc.cluster.local
port:
number: 5000
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: flask
labels:
app: flask
spec:
replicas: 1
selector:
matchLabels:
app: flask
template:
metadata:
labels:
app: flask
spec:
containers:
- name: flask
image: digitalocean/flask-helloworld
ports:
- containerPort: 5000
---
apiVersion: v1
kind: Service
metadata:
name: flask-service
spec:
selector:
app.kubernetes.io/name: flask
ports:
- name: name-of-service-port
protocol: TCP
port: 80
targetPort: 5000
Thanks for your support here!
Cheers
EDIT:
here the updated service definition
apiVersion: v1
kind: Service
metadata:
name: flask
labels:
app: flask
service: flask
spec:
ports:
- port: 5000
name: http
selector:
app: flask

Answer 1

I would suggest you look at this sample from the istio repo:
https://github.com/istio/istio/tree/master/samples/helloworld
This helloworld app is a flask app and you can find the python source code in src
Syntax
In your yaml you do not have --- between your Gateway and VirtualService.
DNS
You also don't make mention of DNS IE you need to make sure that the box you are running curl on has the ability to resolve your domain hello.com to the istio service ip. Since you are using minikube you could add an entry to your OS hosts file.
Routability
It has the ability to send requests to it, IE if you are outside the cluster you need an external ip or do something with kubectl port-forward ...
I hope this helps you sort things out!