[AKS] won't create default systempool

Author: wenxuan0923

src/aks-preview/HISTORY.rst

@@ -11,6 +11,10 @@ To release a new version, please select a new version number (usually plus 1 to
 
 Pending
 +++++++
+
+19.0.0b9
++++++++
+* `az aks create --enable-hosted-system`: no longer provision default system node pool when creating an automatic cluster with hosted system enabled.
 * `az aks machine update`: Add support for updating machine tags, node taints and node labels.
 * Fix `az aks bastion` subshell defaulting to cmd on Windows when invoked from PowerShell by implementing grandparent process detection to identify the actual user shell. 
 

src/aks-preview/azext_aks_preview/managed_cluster_decorator.py

@@ -4710,6 +4710,10 @@ def set_up_enable_hosted_components(self, mc: ManagedCluster) -> ManagedCluster:
                 mc.hosted_system_profile = self.models.ManagedClusterHostedSystemProfile()  # pylint: disable=no-member
             mc.hosted_system_profile.enabled = True
 
+            # Remove default agent pool profiles when hosted system profile is enabled
+            if mc.agent_pool_profiles is not None:
+                mc.agent_pool_profiles = None
+
         return mc
 
     # pylint: disable=unused-argument
@@ -4779,6 +4783,7 @@ def construct_mc_profile_preview(self, bypass_restore_defaults: bool = False) ->
         # set up user-defined scheduler configuration for kube-scheduler upstream
         mc = self.set_up_upstream_kubescheduler_user_configuration(mc)
         # set up enable hosted components
+        # enabling hosted components will remove the default agent pool profiles from the mc object
         mc = self.set_up_enable_hosted_components(mc)
 
         # validate the azure cli core version