This is needed to support the new test framework (with local testing). Consider backing it with [ServiceEntry config](https://github.com/istio/api/blob/master/networking/v1alpha3/service_entry.proto). Along those lines, we may be able to make use of the [external discovery service](https://github.com/istio/istio/blob/master/pilot/pkg/serviceregistry/external/servicediscovery.go).