Add `--converge` argument for osc stack update

This patch add `--converge` argument for osc stack update. This
flag will be used as the trigger for observe on reality.
implements bp get-reality-for-resources

depends-on: I151b575b714dcc9a5971a1573c126152ecd7ea93
Change-Id: If35e1b9234cab173b3c46601bbd331aceebcbcb3

heatclient/osc/v1/stack.py

@@ -278,6 +278,11 @@ class UpdateStack(command.ShowOne):
             help=_('Wait until stack goes to UPDATE_COMPLETE or '
                    'UPDATE_FAILED')
         )
+        parser.add_argument(
+            '--converge',
+            action='store_true',
+            help=_('Stack update with observe on reality.')
+        )
 
         return parser
 
@@ -354,6 +359,9 @@ class UpdateStack(command.ShowOne):
                                             limit=1)
             marker = events[0].id if events else None
 
+        if parsed_args.converge:
+            fields['converge'] = True
+
         client.stacks.update(**fields)
 
         if parsed_args.wait:

heatclient/tests/unit/osc/v1/test_stack.py

@@ -304,6 +304,16 @@ class TestStackUpdate(TestStack):
 
         self.stack_client.update.assert_called_with(**kwargs)
 
+    def test_stack_update_converge(self):
+        arglist = ['my_stack', '-t', self.template_path, '--converge']
+        kwargs = copy.deepcopy(self.defaults)
+        kwargs['converge'] = True
+        parsed_args = self.check_parser(self.cmd, arglist, [])
+
+        self.cmd.take_action(parsed_args)
+
+        self.stack_client.update.assert_called_with(**kwargs)
+
     def test_stack_update_pre_update(self):
         arglist = ['my_stack', '-t', self.template_path, '--pre-update', 'a']
         kwargs = copy.deepcopy(self.defaults)

releasenotes/notes/add-converge-in-osc-stack-update-10f256589f628d13.yaml

@@ -0,0 +1,8 @@
+---
+features:
+  - Adds '--converge' option for stack update with openstackclient. If
+    specified, existing resource attributes (which may have diverged) are
+    compared with the resource properties in the template used for update.
+
+    Usage:
+        # openstack stack update --converge ... <stack_name>