in istio, how a virtualservice defined in a namespace can use a gateway defined in another namespace
If it´s not in the same namespace as virtual service, you have to specify that in virtual service
Check the spec.gateways section
apiVersion: networking.istio.io/v1alpha3kind: VirtualServicemetadata: name: bookinfo-Mongo namespace: bookinfo-namespacespec: gateways: - some-config-namespace/my-gateway # can omit the namespace if gateway is in same namespace as virtual service.apiVersion: networking.istio.io/v1alpha3kind: Gatewaymetadata: name: my-gateway namespace: some-config-namespaceThere is related istio documentation about that.