Improve gateway_ip updation for subnet

Allow update 'gateway_ip' to null or empty for
neutron subnet, and keep the same behavior as
creation.
Also, this change adds some related functional
tests for neutron subnet resource.

Closes-Bug: #1510800
Change-Id: Ib5511402e1d118457356a8add0042be2b157eb24

heat/engine/resources/openstack/neutron/subnet.py

@@ -137,9 +137,12 @@ class Subnet(neutron.NeutronResource):
         ),
         GATEWAY_IP: properties.Schema(
             properties.Schema.STRING,
-            _('The gateway IP address. Set to any of [ null | ~ | "" ] to '
+            _('The gateway IP address. Set to any of [ null | ~ | "" ] '
-              'create the subnet without a gateway. If omitted, the first IP '
+              'to create/update a subnet without a gateway. '
-              'address within the subnet is assigned to the gateway.'),
+              'If omitted when creation, neutron will assign the first '
+              'free IP address within the subnet to the gateway '
+              'automatically. If remove this from template when update, '
+              'the old gateway IP address will be detached.'),
             update_allowed=True
         ),
         ENABLE_DHCP: properties.Schema(
@@ -354,6 +357,10 @@ class Subnet(neutron.NeutronResource):
             if (self.NAME in prop_diff and
                     prop_diff[self.NAME] is None):
                 prop_diff[self.NAME] = self.physical_resource_name()
+
+            # If the new value is '', set to None
+            self._null_gateway_ip(prop_diff)
+
             self.client().update_subnet(
                 self.resource_id, {'subnet': prop_diff})
 

heat/tests/openstack/neutron/test_neutron_subnet.py

@@ -121,9 +121,10 @@ class NeutronSubnetTest(common.HeatTestCase):
             'enable_dhcp': True,
             'host_routes': [{'destination': '192.168.1.0/24',
                              'nexthop': '194.168.1.2'}],
-            "allocation_pools": [
+            'gateway_ip': '10.0.3.105',
-                {"start": "10.0.3.20", "end": "10.0.3.100"},
+            'allocation_pools': [
-                {"start": "10.0.3.110", "end": "10.0.3.200"}]}}
+                {'start': '10.0.3.20', 'end': '10.0.3.100'},
+                {'start': '10.0.3.110', 'end': '10.0.3.200'}]}}
 
         t = self._test_subnet(u_props=update_props)
         neutronV20.find_resourceid_by_name_or_id(

heat_integrationtests/functional/test_create_update_neutron_subnet.py

@@ -24,10 +24,13 @@ resources:
     properties:
       network: { get_resource: net }
       cidr: 11.11.11.0/24
+      gateway_ip: 11.11.11.5
       allocation_pools: [{start: 11.11.11.10, end: 11.11.11.250}]
 outputs:
   alloc_pools:
     value: {get_attr: [subnet, allocation_pools]}
+  gateway_ip:
+    value: {get_attr: [subnet, gateway_ip]}
 '''
 
 
@@ -36,14 +39,14 @@ class UpdateSubnetTest(functional_base.FunctionalTestsBase):
     def setUp(self):
         super(UpdateSubnetTest, self).setUp()
 
-    def get_alloc_pools(self, stack_identifier):
+    def get_outputs(self, stack_identifier, output_key):
         stack = self.client.stacks.get(stack_identifier)
-        alloc_pools = self._stack_output(stack, 'alloc_pools')
+        output = self._stack_output(stack, output_key)
-        return alloc_pools
+        return output
 
     def test_update_allocation_pools(self):
         stack_identifier = self.stack_create(template=test_template)
-        alloc_pools = self.get_alloc_pools(stack_identifier)
+        alloc_pools = self.get_outputs(stack_identifier, 'alloc_pools')
         self.assertEqual([{'start': '11.11.11.10', 'end': '11.11.11.250'}],
                          alloc_pools)
 
@@ -52,14 +55,14 @@ class UpdateSubnetTest(functional_base.FunctionalTestsBase):
             'allocation_pools: [{start: 11.11.11.10, end: 11.11.11.250}]',
             'allocation_pools: [{start: 11.11.11.10, end: 11.11.11.100}]')
         self.update_stack(stack_identifier, templ_other_pool)
-        new_alloc_pools = self.get_alloc_pools(stack_identifier)
+        new_alloc_pools = self.get_outputs(stack_identifier, 'alloc_pools')
         # the new pools should be the new range
         self.assertEqual([{'start': '11.11.11.10', 'end': '11.11.11.100'}],
                          new_alloc_pools)
 
     def test_update_allocation_pools_to_empty(self):
         stack_identifier = self.stack_create(template=test_template)
-        alloc_pools = self.get_alloc_pools(stack_identifier)
+        alloc_pools = self.get_outputs(stack_identifier, 'alloc_pools')
         self.assertEqual([{'start': '11.11.11.10', 'end': '11.11.11.250'}],
                          alloc_pools)
 
@@ -68,13 +71,13 @@ class UpdateSubnetTest(functional_base.FunctionalTestsBase):
             'allocation_pools: [{start: 11.11.11.10, end: 11.11.11.250}]',
             'allocation_pools: []')
         self.update_stack(stack_identifier, templ_empty_pools)
-        new_alloc_pools = self.get_alloc_pools(stack_identifier)
+        new_alloc_pools = self.get_outputs(stack_identifier, 'alloc_pools')
         # new_alloc_pools should be []
         self.assertEqual([], new_alloc_pools)
 
     def test_update_to_no_allocation_pools(self):
         stack_identifier = self.stack_create(template=test_template)
-        alloc_pools = self.get_alloc_pools(stack_identifier)
+        alloc_pools = self.get_outputs(stack_identifier, 'alloc_pools')
         self.assertEqual([{'start': '11.11.11.10', 'end': '11.11.11.250'}],
                          alloc_pools)
 
@@ -83,6 +86,45 @@ class UpdateSubnetTest(functional_base.FunctionalTestsBase):
             'allocation_pools: [{start: 11.11.11.10, end: 11.11.11.250}]',
             '')
         self.update_stack(stack_identifier, templ_no_pools)
-        last_alloc_pools = self.get_alloc_pools(stack_identifier)
+        last_alloc_pools = self.get_outputs(stack_identifier, 'alloc_pools')
         # last_alloc_pools should be []
         self.assertEqual([], last_alloc_pools)
+
+    def test_update_gateway_ip(self):
+        stack_identifier = self.stack_create(template=test_template)
+        gw_ip = self.get_outputs(stack_identifier, 'gateway_ip')
+        self.assertEqual('11.11.11.5', gw_ip)
+
+        # Update gateway_ip
+        templ_other_gw_ip = test_template.replace(
+            'gateway_ip: 11.11.11.5', 'gateway_ip: 11.11.11.9')
+        self.update_stack(stack_identifier, templ_other_gw_ip)
+        new_gw_ip = self.get_outputs(stack_identifier, 'gateway_ip')
+        # the gateway_ip should be the new one
+        self.assertEqual('11.11.11.9', new_gw_ip)
+
+    def test_update_gateway_ip_to_empty(self):
+        stack_identifier = self.stack_create(template=test_template)
+        gw_ip = self.get_outputs(stack_identifier, 'gateway_ip')
+        self.assertEqual('11.11.11.5', gw_ip)
+
+        # Update gateway_ip to null(resolve to '')
+        templ_empty_gw_ip = test_template.replace(
+            'gateway_ip: 11.11.11.5', 'gateway_ip: null')
+        self.update_stack(stack_identifier, templ_empty_gw_ip)
+        new_gw_ip = self.get_outputs(stack_identifier, 'gateway_ip')
+        # new gateway_ip should be None
+        self.assertIsNone(new_gw_ip)
+
+    def test_update_to_no_gateway_ip(self):
+        stack_identifier = self.stack_create(template=test_template)
+        gw_ip = self.get_outputs(stack_identifier, 'gateway_ip')
+        self.assertEqual('11.11.11.5', gw_ip)
+
+        # Remove the gateway from template
+        templ_no_gw_ip = test_template.replace(
+            'gateway_ip: 11.11.11.5', '')
+        self.update_stack(stack_identifier, templ_no_gw_ip)
+        new_gw_ip = self.get_outputs(stack_identifier, 'gateway_ip')
+        # new gateway_ip should be None
+        self.assertIsNone(new_gw_ip)