In a dual control plane scenario, the istioctl troubleshooting commands should be able to identify the control plane without a new --revision <rev> argument.

The Istio sidecar injector, istio-sidecar-injector<-revision>, SHOULD record the revision of the injector within the pod metadata. (Currently it sets MESH_CONFIG to contain the name of the Istiod service, but does set the owning control plane revision). I recommend it add a "istio.io/rev" label.

Currently istioctl uses kubectl exec to find ALL Pilot pods. istioctl COULD use metadata added by the injector to distinguish between Pilot pods in the same revision as the sidecar. If we go this route, the Pilot deployment should include "istio.io/rev" (it currently doesn't).

Alternately, istioctl COULD make an additional API call to get services, to find the istiod<-revision> service with "istio.io/rev" label, and then use its selector to find the Istiod pods.

My preference is for the former, which has one less API call, but I could support either approach.

cc @howardjohn @ostromart