using Istio 0.6 on a K8S 1.9.3 cluster installed with ACS engine that is RBAC enabled to AAD the following error occurs when performing manual sidecar injection:

kubectl apply -f <(istioctl kube-inject --debug -f samples/bookinfo/kube/bookinfo.yaml)
Error: No Auth Provider found for name "azure"

custom auth like GCP is already imported/supported:

requesting AAD support be likewise imported/supported:
https://github.com/kubernetes/client-go/tree/master/plugin/pkg/client/auth/azure

original report https://groups.google.com/forum/#!topic/istio-users/DozqNm9edIE