autoscaling : Fix issue when scaling to zero instances

As noted in https://review.openstack.org/#/c/34564, we lack
coverage of the scenario when MinSize is 0 and we scale down
to zero instances then try to do a delete.  We do the wrong
thing here, by creating a GroupedInstance object with name '',
and this would also result in an incorrect update to the
LoadBalancer.  Fix is to reset the resource_id to None.

Fixes bug #1195364
Change-Id: Ie3a52badf35f7e660de9a8f38635d2a09463123a

diff --git a/heat/engine/resources/autoscaling.py b/heat/engine/resources/autoscaling.py
index f19204dc90091aec79d8cccaa33850644c1e608d..1b04c753526358701c348b1df10e306426d1399e 100644 (file)
--- a/heat/engine/resources/autoscaling.py
+++ b/heat/engine/resources/autoscaling.py
@@ -199,7 +199,8 @@ class InstanceGroup(resource.Resource):
                 inst = self._make_instance(victim)
                 inst.destroy()
                 inst_list.remove(victim)
-                self.resource_id_set(','.join(inst_list))
+                # If we shrink to zero, set resource_id back to None
+                self.resource_id_set(','.join(inst_list) or None)
 
             self._lb_reload()
 

diff --git a/heat/tests/test_autoscaling.py b/heat/tests/test_autoscaling.py
index a959371f56a7b0b5e49039b6b1f3e70ba974b025..eb849cacdc5399a19a98854f8a4dd3462aa2b158 100644 (file)
--- a/heat/tests/test_autoscaling.py
+++ b/heat/tests/test_autoscaling.py
@@ -153,6 +153,52 @@ class AutoScalingTest(HeatTestCase):
         for x in range(nmeta):
             Metadata.__set__(mox.IgnoreArg(), expected).AndReturn(None)
 
+    def test_scaling_delete_empty(self):
+        t = template_format.parse(as_template)
+        properties = t['Resources']['WebServerGroup']['Properties']
+        properties['MinSize'] = '0'
+        properties['MaxSize'] = '0'
+        stack = parse_stack(t)
+
+        now = timeutils.utcnow()
+        self.m.ReplayAll()
+        rsrc = self.create_scaling_group(t, stack, 'WebServerGroup')
+        self.assertEqual(None, rsrc.resource_id)
+
+        rsrc.delete()
+        self.m.VerifyAll()
+
+    def test_scaling_adjust_down_empty(self):
+        t = template_format.parse(as_template)
+        properties = t['Resources']['WebServerGroup']['Properties']
+        properties['MinSize'] = '1'
+        properties['MaxSize'] = '1'
+        stack = parse_stack(t)
+
+        self._stub_lb_reload(['WebServerGroup-0'])
+        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('WebServerGroup-0', rsrc.resource_id)
+
+        # Reduce the min size to 0, should complete without adjusting
+        update_snippet = copy.deepcopy(rsrc.parsed_template())
+        update_snippet['Properties']['MinSize'] = '0'
+        self.assertEqual(None, rsrc.update(update_snippet))
+        self.assertEqual('WebServerGroup-0', rsrc.resource_id)
+
+        # trigger adjustment to reduce to 0, resource_id should be None
+        self._stub_lb_reload([])
+        self._stub_meta_expected(now, 'ChangeInCapacity : -1')
+        self.m.ReplayAll()
+        rsrc.adjust(-1)
+        self.assertEqual(None, rsrc.resource_id)
+
+        rsrc.delete()
+        self.m.VerifyAll()
+
     def test_scaling_group_update_replace(self):
         t = template_format.parse(as_template)
         stack = parse_stack(t)