stack-update -x tolerate no template

Replacement for the approach outlined in
https://review.openstack.org/#/c/154692/

This works with the following heat changes to enable
full PATCH update functionality, including omitting
the template or environment:

https://review.openstack.org/#/c/205754/
https://review.openstack.org/#/c/154619/

Closes-Bug: #1224828
Change-Id: I2a82936743badb69f0de5a6ca64f95ae63a35358

4 files changed, 61 insertions, 4 deletions

diff --git a/heatclient/common/template_utils.py b/heatclient/common/template_utils.py
index ca0885d..e71a3b1 100644
--- a/heatclient/common/template_utils.py
+++ b/heatclient/common/template_utils.py
@@ -28,7 +28,7 @@ from heatclient.openstack.common._i18n import _
 
 def get_template_contents(template_file=None, template_url=None,
                           template_object=None, object_request=None,
-                          files=None):
+                          files=None, existing=False):
 
     # Transform a bare file path to a file:// URL.
     if template_file:
@@ -41,6 +41,8 @@ def get_template_contents(template_file=None, template_url=None,
         template_url = template_object
         tpl = object_request and object_request('GET',
                                                 template_object)
+    elif existing:
+        return {}, None
     else:
         raise exc.CommandError(_('Need to specify exactly one of '
                                '%(arg1)s, %(arg2)s or %(arg3)s') %
diff --git a/heatclient/tests/unit/test_shell.py b/heatclient/tests/unit/test_shell.py
index 2495303..133b0e9 100644
--- a/heatclient/tests/unit/test_shell.py
+++ b/heatclient/tests/unit/test_shell.py
@@ -2223,6 +2223,51 @@ class ShellTestUserPass(ShellBase):
         for r in required:
             self.assertRegexpMatches(update_text, r)
 
+    def test_stack_update_with_existing_template(self):
+        self.register_keystone_auth_fixture()
+        resp = fakes.FakeHTTPResponse(
+            202,
+            'Accepted',
+            {},
+            'The request is accepted for processing.')
+        expected_data = {
+            'files': {},
+            'environment': {},
+            'template': None,
+            'parameters': {}}
+        if self.client is http.HTTPClient:
+            headers = {'X-Auth-Key': 'password', 'X-Auth-User': 'username'}
+        else:
+            headers = {}
+        if self.client == http.SessionClient:
+            self.client.request(
+                '/stacks/teststack2/2', 'PATCH',
+                data=expected_data,
+                headers=headers
+            ).AndReturn(resp)
+        else:
+            self.client.json_request(
+                'PATCH', '/stacks/teststack2/2',
+                data=expected_data,
+                headers=headers
+            ).AndReturn((resp, None))
+        fakes.script_heat_list(client=self.client)
+
+        self.m.ReplayAll()
+
+        update_text = self.shell(
+            'stack-update teststack2/2 '
+            '--existing')
+
+        required = [
+            'stack_name',
+            'id',
+            'teststack2',
+            '1'
+        ]
+        for r in required:
+            self.assertRegexpMatches(update_text, r)
+
     def test_stack_update_with_tags(self):
         self.register_keystone_auth_fixture()
         template_file = os.path.join(TEST_VAR_DIR, 'minimal.template')
diff --git a/heatclient/tests/unit/test_template_utils.py b/heatclient/tests/unit/test_template_utils.py
index 9f917b3..7b584cc 100644
--- a/heatclient/tests/unit/test_template_utils.py
+++ b/heatclient/tests/unit/test_template_utils.py
@@ -436,6 +436,12 @@ class TestGetTemplateContents(testtools.TestCase):
              '--template-url or --template-object'),
             str(ex))
 
+    def test_get_template_contents_file_none_existing(self):
+        files, tmpl_parsed = template_utils.get_template_contents(
+            existing=True)
+        self.assertEqual(None, tmpl_parsed)
+        self.assertEqual({}, files)
+
     def test_get_template_contents_parse_error(self):
         with tempfile.NamedTemporaryFile() as tmpl_file:
 
diff --git a/heatclient/v1/shell.py b/heatclient/v1/shell.py
index 386a045..59c3607 100644
--- a/heatclient/v1/shell.py
+++ b/heatclient/v1/shell.py
@@ -442,11 +442,14 @@ def do_stack_show(hc, args):
            'would be the content of the file'),
            action='append')
 @utils.arg('-x', '--existing', default=False, action="store_true",
-           help=_('Re-use the set of parameters of the current stack. '
+           help=_('Re-use the template, parameters and environment of the '
+           'current stack. If the template argument is omitted then the '
+           'existing template is used. If no %(env_arg)s is specified then '
+           'the existing environment is used. '
            'Parameters specified in %(arg)s will patch over the existing '
            'values in the current stack. Parameters omitted will keep '
            'the existing values.')
-           % {'arg': '--parameters'})
+           % {'arg': '--parameters', 'env_arg': '--environment-file'})
 @utils.arg('-c', '--clear-parameter', metavar='<PARAMETER>',
            help=_('Remove the parameters from the set of parameters of '
            'current stack for the %(cmd)s. The default value in the '
@@ -464,7 +467,8 @@ def do_stack_update(hc, args):
         args.template_file,
         args.template_url,
         args.template_object,
-        _authenticated_fetcher(hc))
+        _authenticated_fetcher(hc),
+        existing=args.existing)
 
     env_files, env = template_utils.process_multiple_environments_and_files(
         env_paths=args.environment_file)