Add quickstart sample for private AKS cluster with custom DNS

quickstart/301-aks-private-cluster/dns-zone-link.sh

@@ -0,0 +1,35 @@
+#!/bin/bash
+# Query AKS private DNS zone and then link it to custom DNS VNet.
+set -e
+
+wait-for-node-resource-group() {
+    NODE_RESOURCE_GROUP=$(az aks show -g ${AKS_RESOURCE_GROUP} -n ${AKS_CLUSTER_NAME} -o json 2>/dev/null | jq -r '.nodeResourceGroup')
+    while [ "${NODE_RESOURCE_GROUP}" == "" ]; do
+        echo "Waiting for node resource group..."
+        sleep 5
+        NODE_RESOURCE_GROUP=$(az aks show -g ${AKS_RESOURCE_GROUP} -n ${AKS_CLUSTER_NAME} -o json 2>/dev/null | jq -r '.nodeResourceGroup')
+    done
+}
+
+wait-for-private-dns-zone() {
+    length=$(az network private-dns zone list -g ${NODE_RESOURCE_GROUP} -o json 2>/dev/null | jq '. | length')
+    while [[ $length -eq 0 ]]; do
+        echo "Waiting for private DNS zone..."
+        sleep 5
+        length=$(az network private-dns zone list -g ${NODE_RESOURCE_GROUP} -o json 2>/dev/null | jq '. | length')
+    done
+}
+
+wait-for-node-resource-group
+NODE_RESOURCE_GROUP=$(az aks show -g ${AKS_RESOURCE_GROUP} -n ${AKS_CLUSTER_NAME} -o json 2>/dev/null | jq -r '.nodeResourceGroup')
+wait-for-private-dns-zone
+ZONE_NAME=$(az network private-dns zone list -g ${NODE_RESOURCE_GROUP} -o json | jq -r '.[0].name')
+echo "Get the private DNS Zone ${ZONE_NAME}"
+az network private-dns link vnet create -o json \
+    -g ${NODE_RESOURCE_GROUP} \
+    -n private-dns-link \
+    --registration-enabled false \
+    --zone-name ${ZONE_NAME} \
+    --virtual-network ${DNS_VNET}
+
+echo "Private DNS Zone ${ZONE_NAME} has been linked to VNet ${DNS_VNET}."