How to bind gateway to a specific namespace? - kubernetes

Question

I have the following scenario:
When the user A enter the address foo.example1.example.com in the
browser, then it should call the service FOO in the namespace
example1.
When the user B enter the address foo.example1.example.com in the
browser, then it should call the service FOO in the namespace
example2.
I am using istio, the question is, how to configure the gateway, that is bind specific to a namespace:
Look at an example of istio gateway configuration:
$ kubectl apply -f - <<EOF
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
name: ns_example1
spec:
selector:
istio: ingressgateway # use Istio default gateway implementation
servers:
- port:
number: 80
name: http
protocol: HTTP
hosts:
- "example1.example.com"
EOF
When I would deploy the gateway, then it will apply to current namespace but I would like to specify a namespace.
How to assign a gateway to specific namespace?

Answer 1

I think this link should answer your question.
There is many things You won't need, but there is idea You want to apply to your istio cluster.
So You need 1 gateway and 2 virtual services.
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
name: foocorp-gateway
namespace: default
spec:
selector:
istio: ingressgateway # use istio default ingress gateway
servers:
- port:
number: 80
name: http-example1
protocol: HTTP
hosts:
- "example1.example.com"
- port:
number: 80
name: http-example2
protocol: HTTP
hosts:
- "example2.example.com"
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
name: example1
namespace: ex1
spec:
hosts:
- "example1.example.com"
gateways:
- foocorp-gateway
http:
- match:
- uri:
exact: /
route:
- destination:
host: example1.ex1.svc.cluster.local
port:
number: 80
---
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
name: example2
namespace: ex2
spec:
hosts:
- "example2.example.com"
gateways:
- foocorp-gateway
http:
- match:
- uri:
exact: /
route:
- destination:
host: example2.ex2.svc.cluster.local
port:
number: 80
EDIT
You can create gateway in namespace ex1 and ex2, then just change gateway field in virtual service and it should work.
Remember to add namespace/gateway, not only gateway name, like there.
gateways:
- some-config-namespace/gateway-name
Let me know if that help You.