Nginx ingress controller passes ingress route to the service endpoint.

ingress_proxy_route.txt

$ kubectl get ing
NAME            RULE          BACKEND   ADDRESS
nginx-ingress   -                       
                foo.bar.com   
                /dash         kubernetes-dashboard:9090

$ kubectl describe svc kubernetes-dashboard
Name:			kubernetes-dashboard
Namespace:		default
Labels:			app=kubernetes-dashboard
Selector:		app=kubernetes-dashboard
Type:			ClusterIP
IP:			10.254.5.210
Port:			<unnamed>	9090/TCP
Endpoints:		172.16.63.46:9090
Session Affinity:	None
No events.

$ curl <ingress-host-ip>/dash -H 'Host: foo.bar.com'
404 page not found

$ kubectl edit ing
$ kubectl get ing
NAME            RULE          BACKEND   ADDRESS
nginx-ingress   -                       
                foo.bar.com   
                /             kubernetes-dashboard:9090

$ curl <ingress-host-ip> -H 'Host: foo.bar.com'
<returns kuberentes-dashboard html as expected>