[RDBMS] az postgres flexible-server update: Add --node-count argu…

…ment to scale up elastic clusters (#30572)

* init

* add update test

src/azure-cli/azure/cli/command_modules/rdbms/_helptext_pg.py

@@ -223,7 +223,7 @@
   - name: >
       Create elastic cluster with node count of 5. Default node count is 2 when --cluster-option is "ElasticCluster".
     text: >
-      az postgres flexible-server create -g testGroup -n testServer --location testLocation --cluster-option ElasticCluster --node-count 5
+      az postgres flexible-server create -g testGroup -n testCluster --location testLocation --cluster-option ElasticCluster --node-count 5
 """
 
 helps['postgres flexible-server show'] = """
@@ -282,6 +282,8 @@
     text: az postgres flexible-server update --resource-group testGroup --name testserver --iops 3000
   - name: Update a flexible server's storage to set Throughput (MB/sec). Server must be using Premium SSD v2 Disks.
     text: az postgres flexible-server update --resource-group testGroup --name testserver --throughput 125
+  - name: Update a flexible server's cluster size by scaling up node count. Must be an Elastic Cluster.
+    text: az postgres flexible-server update --resource-group testGroup --name testcluster --node-count 6
 """
 
 helps['postgres flexible-server restore'] = """

src/azure-cli/azure/cli/command_modules/rdbms/_params.py

@@ -346,6 +346,13 @@ def _flexible_server_params(command_group):
             validator=node_count_validator
         )
 
+        update_node_count_arg_type = CLIArgumentType(
+            type=int,
+            options_list=['--node-count'],
+            help='The number of nodes for elastic cluster. Range of 1 to 10.',
+            validator=node_count_validator
+        )
+
         auto_grow_arg_type = CLIArgumentType(
             arg_type=get_enum_type(['Enabled', 'Disabled']),
             options_list=['--storage-auto-grow'],
@@ -733,6 +740,7 @@ def _flexible_server_params(command_group):
                 c.argument('active_directory_auth', arg_type=active_directory_auth_arg_type)
                 c.argument('password_auth', arg_type=password_auth_arg_type)
                 c.argument('private_dns_zone_arguments', private_dns_zone_arguments_arg_type)
+                c.argument('cluster_size', default=None, arg_type=update_node_count_arg_type)
                 c.argument('yes', arg_type=yes_arg_type)
 
         with self.argument_context('{} flexible-server upgrade'.format(command_group)) as c:

src/azure-cli/azure/cli/command_modules/rdbms/flexible_server_custom_postgres.py

@@ -296,7 +296,7 @@ def flexible_server_update_custom_func(cmd, client, instance,
                                        auto_grow=None,
                                        performance_tier=None,
                                        iops=None, throughput=None,
-                                       yes=False):
+                                       cluster_size=None, yes=False):
 
     # validator
     location = ''.join(instance.location.lower().split())
@@ -322,7 +322,7 @@ def flexible_server_update_custom_func(cmd, client, instance,
                            backup_byok_identity=backup_byok_identity,
                            backup_byok_key=backup_byok_key,
                            performance_tier=performance_tier,
-                           instance=instance)
+                           cluster_size=cluster_size, instance=instance)
 
     server_module_path = instance.__module__
     module = import_module(server_module_path)
@@ -403,6 +403,9 @@ def flexible_server_update_custom_func(cmd, client, instance,
                                                                           password_auth, administrator_login, administrator_login_password)
         auth_config.password_auth = password_auth
 
+    if cluster_size:
+        instance.cluster.cluster_size = cluster_size
+
     params = ServerForUpdate(sku=instance.sku,
                              storage=instance.storage,
                              backup=instance.backup,
@@ -413,6 +416,7 @@ def flexible_server_update_custom_func(cmd, client, instance,
                              identity=identity,
                              data_encryption=data_encryption,
                              auth_config=auth_config,
+                             cluster=instance.cluster,
                              tags=tags)
 
     # High availability can't be updated with existing properties