From a41442e8737b19b02f5c18cf004bd95e9bbde006 Mon Sep 17 00:00:00 2001
From: Zhang Yang <neil.zhangyang@huawei.com>
Date: Mon, 14 Apr 2014 00:25:46 -0700
Subject: [PATCH] Allow DesiredCapacity to be zero

When updating or validating a AutoScaleGroup,
'DesiredCapacity' is ignored if the value is 0.

- Add validation for 'DesiredCapacity' if the value is 0,
- Don't ignore zero when updating.

Change-Id: I830aaf97ebed6b2c77c72b18dc8d222ce23f9a28
Partial-Bug: #1304423
---
 heat/engine/resources/autoscaling.py |  4 +-
 heat/tests/test_autoscaling.py       | 59 ++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+), 2 deletions(-)

diff --git a/heat/engine/resources/autoscaling.py b/heat/engine/resources/autoscaling.py
index 84ccf363c6..3ecc7aff9c 100644
--- a/heat/engine/resources/autoscaling.py
+++ b/heat/engine/resources/autoscaling.py
@@ -607,7 +607,7 @@ class AutoScalingGroup(InstanceGroup, CooldownMixin):
                 if capacity > self.properties[self.MAX_SIZE]:
                     new_capacity = self.properties[self.MAX_SIZE]
             if self.DESIRED_CAPACITY in prop_diff:
-                if self.properties[self.DESIRED_CAPACITY]:
+                if self.properties[self.DESIRED_CAPACITY] is not None:
                     new_capacity = self.properties[self.DESIRED_CAPACITY]
 
             if new_capacity is not None:
@@ -724,7 +724,7 @@ class AutoScalingGroup(InstanceGroup, CooldownMixin):
             msg = _("The size of AutoScalingGroup can not be less than zero")
             raise exception.StackValidationFailed(message=msg)
 
-        if self.properties[self.DESIRED_CAPACITY]:
+        if self.properties[self.DESIRED_CAPACITY] is not None:
             desired_capacity = self.properties[self.DESIRED_CAPACITY]
             if desired_capacity < min_size or desired_capacity > max_size:
                 msg = _("DesiredCapacity must be between MinSize and MaxSize")
diff --git a/heat/tests/test_autoscaling.py b/heat/tests/test_autoscaling.py
index 700358d188..cde35e824e 100644
--- a/heat/tests/test_autoscaling.py
+++ b/heat/tests/test_autoscaling.py
@@ -172,6 +172,17 @@ class AutoScalingTest(HeatTestCase):
         instance.Instance.check_create_complete(
             cookie).MultipleTimes().AndReturn(True)
 
+    def _stub_delete(self, num):
+        self._stub_validate()
+        self.m.StubOutWithMock(instance.Instance, 'handle_delete')
+        self.m.StubOutWithMock(instance.Instance, 'check_delete_complete')
+        task = object()
+        for x in range(num):
+            instance.Instance.handle_delete().AndReturn(task)
+        instance.Instance.check_delete_complete(task).AndReturn(False)
+        instance.Instance.check_delete_complete(
+            task).MultipleTimes().AndReturn(True)
+
     def _stub_lb_reload(self, num, unset=True, nochange=False):
         expected_list = [self.dummy_instance_id] * num
         if unset:
@@ -246,6 +257,7 @@ class AutoScalingTest(HeatTestCase):
         properties = t['Resources']['WebServerGroup']['Properties']
         properties['MinSize'] = '0'
         properties['MaxSize'] = '0'
+        properties['DesiredCapacity'] = '0'
         stack = utils.parse_stack(t, params=self.params)
         self._stub_lb_reload(0)
         self.m.ReplayAll()
@@ -642,6 +654,37 @@ class AutoScalingTest(HeatTestCase):
         rsrc.delete()
         self.m.VerifyAll()
 
+    def test_scaling_group_update_ok_desired_zero(self):
+        t = template_format.parse(as_template)
+        properties = t['Resources']['WebServerGroup']['Properties']
+        properties['MinSize'] = '1'
+        properties['MaxSize'] = '3'
+        stack = utils.parse_stack(t, params=self.params)
+
+        self._stub_lb_reload(1)
+        now = timeutils.utcnow()
+        self._stub_meta_expected(now, 'ExactCapacity : 1')
+        self._stub_create(1)
+        self.m.ReplayAll()
+        rsrc = self.create_scaling_group(t, stack, 'WebServerGroup')
+        self.assertEqual(1, len(rsrc.get_instance_names()))
+
+        # Increase min size to 2 via DesiredCapacity, should adjust
+        self._stub_lb_reload(0)
+        self._stub_meta_expected(now, 'ExactCapacity : 0')
+        self._stub_delete(1)
+        self.m.ReplayAll()
+
+        update_snippet = copy.deepcopy(rsrc.parsed_template())
+        update_snippet['Properties']['MinSize'] = '0'
+        update_snippet['Properties']['DesiredCapacity'] = '0'
+        scheduler.TaskRunner(rsrc.update, update_snippet)()
+        self.assertEqual(0, len(rsrc.get_instance_names()))
+        self.assertEqual(0, rsrc.properties['DesiredCapacity'])
+
+        rsrc.delete()
+        self.m.VerifyAll()
+
     def test_scaling_group_update_ok_desired_remove(self):
         t = template_format.parse(as_template)
         properties = t['Resources']['WebServerGroup']['Properties']
@@ -1634,6 +1677,22 @@ class AutoScalingTest(HeatTestCase):
         expected_msg = "DesiredCapacity must be between MinSize and MaxSize"
         self.assertEqual(expected_msg, str(e))
 
+    def test_invalid_desiredcapacity_zero(self):
+        t = template_format.parse(as_template)
+        properties = t['Resources']['WebServerGroup']['Properties']
+        properties['MinSize'] = '1'
+        properties['MaxSize'] = '3'
+        properties['DesiredCapacity'] = '0'
+
+        stack = utils.parse_stack(t, params=self.params)
+
+        e = self.assertRaises(exception.StackValidationFailed,
+                              self.create_scaling_group, t,
+                              stack, 'WebServerGroup')
+
+        expected_msg = "DesiredCapacity must be between MinSize and MaxSize"
+        self.assertEqual(expected_msg, str(e))
+
 
 class TestInstanceGroup(HeatTestCase):
     params = {'KeyName': 'test', 'ImageId': 'foo'}