How to use an FQDN in a host of Istio VirtualService Destination field

[ysk24ok]

When we go through the tutorial, the following VirtualService object will be created.
Is there a way to use a fully qualified domain name (FQDN) in host of the Destination field?
I'm asking this because our k8s has a rule that an FQDN must be specified to the field as Istio recommends.

apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  name: iris-model
  namespace: seldon
spec:
  gateways:
  - istio-system/seldon-gateway
  hosts:
  - '*'
  http:
  - match:
    - uri:
        prefix: /seldon/seldon/iris-model/
    rewrite:
      uri: /
    route:
    - destination:
        host: iris-model-default
        port:
          number: 8000
        subset: default
  - match:
    - headers:
        namespace:
          exact: seldon
        seldon:
          exact: iris-model
      uri:
        regex: .*tensorflow.*|.*seldon.protos.*|.*inference.*
    route:
    - destination:
        host: iris-model-default
        port:
          number: 5001
        subset: default

https://github.com/SeldonIO/seldon-core/blob/v1.14.1/operator/controllers/seldondeployment_controller.go#L353
It doesn't seem possible to me because pSvcName is expected to be a service name. It can be customized by passing seldon.io/svc-name, but it's still just a service name.

If it's not possible, as I really need this feature, I may be going to contribute to this project.
I have the following ideas to implement the feature. Let me know which you think is better or if you have a better idea than mine.

1. Use an FQDN by default
   • I think it's OK to use an FQDN by default because SeldonDeploument creates a VS and a service in the same namespace, so IIUC using the short name or FQDN doesn't matter.
2. Add a new option as a helm value such as istio.use_fqdn or as an annotation such as seldon.io/istio-use-fqdn to the SeldonDeployment

[ukclivecox]

Are you saying that the seldon.io/istio-host as discussed here is not what you need?

[ysk24ok]

No, seldon.io/istio-host is not what I want IIUC. It's meant to be used for spec.hosts.
I'd like to use a FQDN in the host of Destination field.