I've setup Istio using the helm charts, and I'm trying to expose services to the istio-ingressgateway.

Here's the config I've decided to go with:

apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  name: grafana-gateway
  namespace: istio-system
spec:
  selector:
    istio: ingressgateway
  servers:
  - port:
      number: 31400
      name: http
      protocol: HTTP
    hosts:
    - "*"
---
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  name: kiali-gateway
  namespace: istio-system
spec:
  selector:
    istio: ingressgateway
  servers:
  - port:
      number: 15029
      name: http
      protocol: HTTP
    hosts:
    - "*"
---
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  name: prometheus-gateway
  namespace: istio-system
spec:
  selector:
    istio: ingressgateway
  servers:
  - port:
      number: 15030
      name: http
      protocol: HTTP
    hosts:
    - "*"
---
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: grafana-vts
  namespace: istio-system
spec:
  hosts:
  - "*"
  gateways:
  - grafana-gateway
  http:
  - match:
    - uri:
        prefix: /
    route:
    - destination:
        host: grafana.istio-system.svc.cluster.local
        port: 
          number: 3000
---
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: kiali-vts
  namespace: istio-system
spec:
  hosts:
  - "*"
  gateways:
  - kiali-gateway
  http:
  - match:
    - uri:
        prefix: /
    route:
    - destination:
        host: kiali.istio-system.svc.cluster.local
        port: 
          number: 20001
---
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: prometheus-vts
  namespace: istio-system
spec:
  hosts:
  - "*"
  gateways:
  - prometheus-gateway
  http:
  - match:
    - uri:
        prefix: /
    route:
    - destination:
        host: prometheus.istio-system.svc.cluster.local
        port: 
          number: 9090

However - this only routes grafana through ports 31400, 15029 and 15030, while it's supposed to do so just for 31400.

If I'm using just one Gateway and rewrite the uri, it throws up a 404 error/tells me the reverse-proxy isn't setup properly

apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  name: all-gateway
  namespace: istio-system
spec:
  selector:
    istio: ingressgateway
  servers:
  - port:
      number: 80
      name: http
      protocol: HTTP
    hosts:
    - "*"
---
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: grafana-vts
  namespace: istio-system
spec:
  hosts:
  - "*"
  gateways:
  - all-gateway
  http:
  - match:
    - uri:
        prefix: "/grafana"
      rewrite:
        uri: /
    route:
    - destination:
        host: grafana.istio-system.svc.cluster.local
        port: 
          number: 3000
and etc...

I'm a bit new to istio, and the examples I've browsed through don't exactly talk about these. If you've got an idea, it'd be swell - is it because of how I've wildcarded the hosts?