Don't always replace FAILED ServerGroup resources

ServerGroup resources work as scheduler hints for server
resources and replacement of it replaces the servers which
is undesirable in many circumstances.

- We don't allow update of ServerGroup resource properties
- If not created (CREATE_FAILED) without resource_id they will
  be replaced
- If does not exist in nova they would be created
- If exist in nova, FAILED resource status would be just
  changed to COMPLETE

Conflicts:
	heat/tests/openstack/nova/test_server_group.py

Fixed conflicts caused by 7416442401 ,
which is present in stable/xena and later.

Task: 45748

Change-Id: I096dff2b541a5aa8afbbbcea5161e7ca1c244039
(cherry picked from commit a0e072b320)
(cherry picked from commit f9f5d2cc36)
(cherry picked from commit ead7cd61bd)
(cherry picked from commit a4f2f6053c)
(cherry picked from commit 007ff4447b)
(cherry picked from commit 43c3d6ea30)

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

@@ -80,6 +80,16 @@ class ServerGroup(resource.Resource):
                                                    policies=policies)
         self.resource_id_set(server_group.id)
 
+    def needs_replace_failed(self):
+        if not self.resource_id:
+            return True
+
+        with self.client_plugin().ignore_not_found:
+            self._show_resource()
+            return False
+
+        return True
+
     def physical_resource_name(self):
         name = self.properties[self.NAME]
         if name:

heat/tests/openstack/nova/test_server_group.py

@@ -15,6 +15,9 @@ import json
 
 import mock
 
+from novaclient import exceptions
+from oslo_utils import excutils
+
 from heat.common import template_format
 from heat.engine.clients.os import nova
 from heat.engine import scheduler
@@ -54,6 +57,20 @@ class NovaServerGroupTest(common.HeatTestCase):
         # create mock clients and objects
         nova = mock.MagicMock()
         self.sg.client = mock.MagicMock(return_value=nova)
+
+        class FakeNovaPlugin(object):
+
+            @excutils.exception_filter
+            def ignore_not_found(self, ex):
+                if not isinstance(ex, exceptions.NotFound):
+                    raise ex
+
+            def is_conflict(self, ex):
+                return False
+
+        self.patchobject(excutils.exception_filter, '__exit__')
+        self.patchobject(self.sg, 'client_plugin',
+                         return_value=FakeNovaPlugin())
         self.sg_mgr = nova.server_groups
 
     def _create_sg(self, name):
@@ -103,3 +120,21 @@ class NovaServerGroupTest(common.HeatTestCase):
         self.sg.client().server_groups = s_groups
         self.assertEqual({'server_gr': 'info'}, self.sg.FnGetAtt('show'))
         s_groups.get.assert_called_once_with('test')
+
+    def test_needs_replace_failed(self):
+        self._create_sg('test')
+        self.sg.state_set(self.sg.CREATE, self.sg.FAILED)
+        mock_show_resource = self.patchobject(self.sg, '_show_resource')
+        mock_show_resource.side_effect = [exceptions.NotFound(404), None]
+
+        self.sg.resource_id = None
+        self.assertTrue(self.sg.needs_replace_failed())
+        self.assertEqual(0, mock_show_resource.call_count)
+
+        self.sg.resource_id = 'sg_id'
+        self.assertTrue(self.sg.needs_replace_failed())
+        self.assertEqual(1, mock_show_resource.call_count)
+
+        mock_show_resource.return_value = None
+        self.assertFalse(self.sg.needs_replace_failed())
+        self.assertEqual(2, mock_show_resource.call_count)