Add user_data_update_policy property to OS::Nova::Server

This may be set to either 'REPLACE' (default) or 'IGNORE'.
This allows template authors to choose the desired behaviour when the
user_data property is changed.

Co-Authored-By: Steve Hardy <shardy@redhat.com>

Change-Id: I3239c7252a2c329330283b86181abd52aee9e967
Closes-Bug: #1539541

heat/engine/resources/openstack/nova/server.py

@@ -56,14 +56,14 @@ class Server(stack_user.StackUser, sh.SchedulerHintsMixin,
         ADMIN_USER, AVAILABILITY_ZONE, SECURITY_GROUPS, NETWORKS,
         SCHEDULER_HINTS, METADATA, USER_DATA_FORMAT, USER_DATA,
         RESERVATION_ID, CONFIG_DRIVE, DISK_CONFIG, PERSONALITY,
-        ADMIN_PASS, SOFTWARE_CONFIG_TRANSPORT
+        ADMIN_PASS, SOFTWARE_CONFIG_TRANSPORT, USER_DATA_UPDATE_POLICY
     ) = (
         'name', 'image', 'block_device_mapping', 'block_device_mapping_v2',
         'flavor', 'flavor_update_policy', 'image_update_policy', 'key_name',
         'admin_user', 'availability_zone', 'security_groups', 'networks',
         'scheduler_hints', 'metadata', 'user_data_format', 'user_data',
         'reservation_id', 'config_drive', 'diskConfig', 'personality',
-        'admin_pass', 'software_config_transport'
+        'admin_pass', 'software_config_transport', 'user_data_update_policy'
     )
 
     _BLOCK_DEVICE_MAPPING_KEYS = (
@@ -446,10 +446,22 @@ class Server(stack_user.StackUser, sh.SchedulerHintsMixin,
                 constraints.AllowedValues(_SOFTWARE_CONFIG_TRANSPORTS),
             ]
         ),
+        USER_DATA_UPDATE_POLICY: properties.Schema(
+            properties.Schema.STRING,
+            _('Policy on how to apply a user_data update; either by '
+              'ignorning it or by replacing the entire server.'),
+            default='REPLACE',
+            constraints=[
+                constraints.AllowedValues(['REPLACE', 'IGNORE']),
+            ],
+            support_status=support.SupportStatus(version='6.0.0'),
+            update_allowed=True
+        ),
         USER_DATA: properties.Schema(
             properties.Schema.STRING,
             _('User data script to be executed by cloud-init.'),
-            default=''
+            default='',
+            update_allowed=True
         ),
         RESERVATION_ID: properties.Schema(
             properties.Schema.STRING,
@@ -1093,6 +1105,12 @@ class Server(stack_user.StackUser, sh.SchedulerHintsMixin,
             if image_update_policy == 'REPLACE':
                 return True
 
+        if self.USER_DATA in changed_properties_set:
+            ud_update_policy = (
+                after_props.get(self.USER_DATA_UPDATE_POLICY) or
+                before_props.get(self.USER_DATA_UPDATE_POLICY))
+            return ud_update_policy == 'REPLACE'
+
     def handle_update(self, json_snippet, tmpl_diff, prop_diff):
         if 'Metadata' in tmpl_diff:
             # If SOFTWARE_CONFIG user_data_format is enabled we require

heat/tests/openstack/nova/test_server.py

@@ -2129,6 +2129,46 @@ class ServersTest(common.HeatTestCase):
         updater = scheduler.TaskRunner(server.update, update_template)
         self.assertRaises(exception.UpdateReplace, updater)
 
+    def test_server_update_server_userdata_replace(self):
+        stack_name = 'update_udatrep'
+        (tmpl, stack) = self._setup_test_stack(stack_name)
+        self.m.StubOutWithMock(nova.NovaClientPlugin, '_create')
+        nova.NovaClientPlugin._create().AndReturn(self.fc)
+        self._mock_get_image_id_success('F17-x86_64-gold', 'image_id')
+        self.m.ReplayAll()
+        resource_defns = tmpl.resource_definitions(stack)
+        server = servers.Server('server_update_userdata_replace',
+                                resource_defns['WebServer'], stack)
+
+        update_template = copy.deepcopy(server.t)
+        update_template['Properties']['user_data'] = 'changed'
+        server.action = server.CREATE
+        updater = scheduler.TaskRunner(server.update, update_template)
+        self.assertRaises(exception.UpdateReplace, updater)
+
+    def test_server_update_server_userdata_ignore(self):
+        stack_name = 'update_udatignore'
+        (tmpl, stack) = self._setup_test_stack(stack_name)
+        self.m.StubOutWithMock(nova.NovaClientPlugin, '_create')
+        nova.NovaClientPlugin._create().AndReturn(self.fc)
+        self._mock_get_image_id_success('F17-x86_64-gold', 'image_id')
+        self.m.ReplayAll()
+        self.patchobject(servers.Server, 'prepare_for_replace')
+        self.patchobject(servers.Server, 'check_update_complete',
+                         return_value=True)
+
+        resource_defns = tmpl.resource_definitions(stack)
+        server = servers.Server('server_update_userdata_ignore',
+                                resource_defns['WebServer'], stack)
+
+        update_template = copy.deepcopy(server.t)
+        update_template['Properties']['user_data'] = 'changed'
+        update_template['Properties']['user_data_update_policy'] = 'IGNORE'
+        server.action = server.CREATE
+        scheduler.TaskRunner(server.update, update_template)()
+        self.assertEqual((server.UPDATE, server.COMPLETE), server.state)
+        self.m.VerifyAll()
+
     def test_server_update_image_replace(self):
         stack_name = 'update_imgrep'
         (tmpl, stack) = self._setup_test_stack(stack_name)

releasenotes/notes/server-add-user-data-update-policy-c34646acfaada4d4.yaml

@@ -0,0 +1,7 @@
+---
+features:
+  - The OS::Nova::Server now supports a new property user_data_update_policy,
+    which may be set to either 'REPLACE' (default) or 'IGNORE' if you wish to
+    allow user_data updates to be ignored on stack update. This is useful when
+    managing a group of servers where changed user_data should apply to new
+    servers without replacing existing servers.