There is some discussion going on now around exposing the request.host in the telemetry. But it’s not yet available in the default requestcount metric. I’ve got some branches in kiali that can expose the info if you add request.host to the telemetry, but you could also look at prometheus directly. To add it you can do the following if you’re installing via helm charts (note - this will not limit it to one workload, i don’t think that’s possible):
add request.host/request_host in the requestcount instance and also in the prometheus handler
then re-run the helm template.
oc project istio-system helm template _output/istio-1.3.0-rc.3/install/kubernetes/helm/istio | oc apply -f-
it may take a few minutes to propagate the change, but then I think you should be able to see request_host in istio_requests_total and hopefully it will provide the info you are looking for.