Add methods to get an existing stack

* Add yardstick/orchestrator/heat.py:HeatStack.get
* Add yardstick/benchmark/contexts/heay.py:HeatContext.retrieve_existing_stack

JIRA: YARDSTICK-886
Change-Id: I6974b79a25f98066a49b1bc8ccd11383e7962091
Signed-off-by: Emma Foley <emma.l.foley@intel.com>

3 files changed, 118 insertions, 5 deletions

diff --git a/yardstick/benchmark/contexts/heat.py b/yardstick/benchmark/contexts/heat.py
index be8815060..ed301a998 100644
--- a/yardstick/benchmark/contexts/heat.py
+++ b/yardstick/benchmark/contexts/heat.py
@@ -26,6 +26,7 @@ from yardstick.benchmark.contexts.model import Server
 from yardstick.benchmark.contexts.model import update_scheduler_hints
 from yardstick.common import exceptions as y_exc
 from yardstick.common.openstack_utils import get_neutron_client
+from yardstick.orchestrator.heat import HeatStack
 from yardstick.orchestrator.heat import HeatTemplate
 from yardstick.common import constants as consts
 from yardstick.common.utils import source_env
@@ -312,6 +313,14 @@ class HeatContext(Context):
              # let the other failures happen, we want stack trace
              raise
 
+    def _retrieve_existing_stack(self, stack_name):
+        stack = HeatStack(stack_name)
+        if stack.get():
+            return stack
+        else:
+            LOG.warning("Stack %s does not exist", self.name)
+            return None
+
     def deploy(self):
         """deploys template into a stack using cloud"""
         LOG.info("Deploying context '%s' START", self.name)
diff --git a/yardstick/orchestrator/heat.py b/yardstick/orchestrator/heat.py
index 403c7e8d9..78e9c3df2 100644
--- a/yardstick/orchestrator/heat.py
+++ b/yardstick/orchestrator/heat.py
@@ -44,6 +44,13 @@ class HeatStack(object):
         self._cloud = shade.openstack_cloud()
         self._stack = None
 
+    def _update_stack_tracking(self):
+        outputs = self._stack.outputs
+        self.outputs = {output['output_key']: output['output_value'] for output
+                        in outputs}
+        if self.uuid:
+            _DEPLOYED_STACKS[self.uuid] = self._stack
+
     def create(self, template, heat_parameters, wait, timeout):
         """Creates an OpenStack stack from a template"""
         with tempfile.NamedTemporaryFile('wb', delete=False) as template_file:
@@ -52,11 +59,21 @@ class HeatStack(object):
             self._stack = self._cloud.create_stack(
                 self.name, template_file=template_file.name, wait=wait,
                 timeout=timeout, **heat_parameters)
-        outputs = self._stack.outputs
-        self.outputs = {output['output_key']: output['output_value'] for output
-                        in outputs}
-        if self.uuid:
-            _DEPLOYED_STACKS[self.uuid] = self._stack
+
+        self._update_stack_tracking()
+
+    def get(self):
+        """Retrieves an existing stack from the target cloud
+
+        Returns a bool indicating whether the stack exists in the target cloud
+        If the stack exists, it will be stored as self._stack
+        """
+        self._stack = self._cloud.get_stack(self.name)
+        if not self._stack:
+            return False
+
+        self._update_stack_tracking()
+        return True
 
     @staticmethod
     def stacks_exist():
diff --git a/yardstick/tests/unit/orchestrator/test_heat.py b/yardstick/tests/unit/orchestrator/test_heat.py
index bde6647ed..9ab8740e3 100644
--- a/yardstick/tests/unit/orchestrator/test_heat.py
+++ b/yardstick/tests/unit/orchestrator/test_heat.py
@@ -9,6 +9,7 @@
 
 import tempfile
 
+import munch
 import mock
 from oslo_serialization import jsonutils
 from oslo_utils import uuidutils
@@ -40,12 +41,16 @@ class HeatStackTestCase(unittest.TestCase):
         self._mock_stack_delete = mock.patch.object(self.heatstack._cloud,
                                                     'delete_stack')
         self.mock_stack_delete = self._mock_stack_delete.start()
+        self._mock_stack_get = mock.patch.object(self.heatstack._cloud,
+                                                 'get_stack')
+        self.mock_stack_get = self._mock_stack_get.start()
 
         self.addCleanup(self._cleanup)
 
     def _cleanup(self):
         self._mock_stack_create.stop()
         self._mock_stack_delete.stop()
+        self._mock_stack_get.stop()
         heat._DEPLOYED_STACKS = {}
 
     def test_create(self):
@@ -101,6 +106,88 @@ class HeatStackTestCase(unittest.TestCase):
         self.assertFalse(heat._DEPLOYED_STACKS)
         self.mock_stack_delete.assert_called_once_with(id, wait=True)
 
+    def test_get(self):
+        # make sure shade/get_stack is called with the appropriate vars
+        self.mock_stack_get.return_value = munch.Munch(
+            id="my-existing-stack-id",
+            outputs=[
+                {
+                 u'output_value': u'b734d06a-dec7-...',
+                 u'output_key': u'ares.demo-test-port-network_id',
+                 u'description': u''
+                },
+                {u'output_value': u'b08da78c-2218-...',
+                 u'output_key': u'ares.demo-test-port-subnet_id',
+                 u'description': u''
+                },
+                {u'output_value': u'10.0.1.0/24',
+                 u'output_key': u'demo-test-subnet-cidr',
+                 u'description': u''
+                },
+                {u'output_value': u'b08da78c-2218-...',
+                 u'output_key': u'demo-test-subnet',
+                 u'description': u''
+                },
+                {u'output_value': u'b1a03624-aefc-...',
+                 u'output_key': u'ares.demo',
+                 u'description': u''
+                },
+                {u'output_value': u'266a8088-c630-...',
+                 u'output_key': u'demo-secgroup',
+                 u'description': u''
+                },
+                {u'output_value': u'10.0.1.5',
+                 u'output_key': u'ares.demo-test-port',
+                 u'description': u''
+                },
+                {u'output_value': u'10.0.1.1',
+                 u'output_key': u'demo-test-subnet-gateway_ip',
+                 u'description': u''
+                },
+                {u'output_value': u'',
+                 u'output_key': u'ares.demo-test-port-device_id',
+                 u'description': u''
+                },
+                {u'output_value': u'172.24.4.7',
+                 u'output_key': u'ares.demo-fip',
+                 u'description': u''
+                },
+                {u'output_value': u'fa:16:3e:6c:c3:0f',
+                 u'output_key': u'ares.demo-test-port-mac_address',
+                 u'description': u''}
+            ]
+        )
+        expected_outputs = {
+            'ares.demo-test-port-network_id': 'b734d06a-dec7-...',
+            'ares.demo-test-port-subnet_id': 'b08da78c-2218-...',
+            'demo-test-subnet-cidr': '10.0.1.0/24',
+            'demo-test-subnet': 'b08da78c-2218-...',
+            'ares.demo': 'b1a03624-aefc-...',
+            'demo-secgroup': '266a8088-c630-...',
+            'ares.demo-test-port': '10.0.1.5',
+            'demo-test-subnet-gateway_ip': '10.0.1.1',
+            'ares.demo-test-port-device_id': '',
+            'ares.demo-fip': '172.24.4.7',
+            'ares.demo-test-port-mac_address': 'fa:16:3e:6c:c3:0f',
+        }
+
+        stack_id = "my-existing-stack-id"
+        self.heatstack.name = "my-existing-stack"
+        self.heatstack.get()
+
+        self.mock_stack_get.assert_called_once_with(self.heatstack.name)
+        self.assertEqual(expected_outputs, self.heatstack.outputs)
+        self.assertEqual(1, len(heat._DEPLOYED_STACKS))
+        self.assertEqual(self.heatstack._stack,
+                         heat._DEPLOYED_STACKS[stack_id])
+
+    def test_get_invalid_name(self):
+        # No context matching this name exists
+        self.mock_stack_get.return_value = []
+        self.heatstack.name = 'not-a-stack'
+        self.heatstack.get()
+        self.assertEqual(0, len(heat._DEPLOYED_STACKS))
+
 
 class HeatTemplateTestCase(unittest.TestCase):