Correct way to specify the EnvoyFilter.RouteConfigurationMatch.gateway for the BookInfo sample application

1

The doc Istio / Envoy Filter states that:

The Istio gateway config’s namespace/name for which this route configuration was generated. Applies only if the context is GATEWAY. Should be in the namespace/name format.

In the Getting Started doc Istio / Getting Started, the BookInfo was associated with the Gateway via:

kubectl apply -f samples/bookinfo/networking/bookinfo-gateway.yaml

I try to specify EnvoyFilter.RouteConfigurationMatch.gateway to istio-system/bookinfo-gateway or default/book-gateway or other combinations that I could think of, none of these works.

My patch:

apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: sample-metadata
  namespace: istio-system
spec:
  configPatches:
  - applyTo: HTTP_ROUTE
    match:
      context: GATEWAY
      routeConfiguration:
        gateway: istio-system/bookinfo-gateway
    patch:
      operation: MERGE
      value:
        metadata:
          filter_metadata:
            envoy.filters.http.lua:
              foo: bar

I am not sure if I missing something here.