Boot a VM in a subnet without gateway

1. What is the problem
We can create a subnet without gateway in the central Neutron, but when
we boot a VM in that subnet, the request fails since local Neutron is
trying to calculate the IP allocation pool based on the central subnet
gateway IP, which is None.

2. What is the solution for the problem
If a central subnet doesn't have gateway, do not re-calculate local IP
allocation pool when creating local subnet.

3. What features need to be implemented to the Tricircle to
realize the solution
Support booting a VM in a subnet that has not gateway

Change-Id: I04f7f9f9926f22bca3490ee46e2163b9c17bb8fe
Closes-Bug: #1693446

tricircle/network/helper.py

@@ -364,6 +364,9 @@ class NetworkHelper(object):
         """
         pools = t_subnet['allocation_pools']
         t_gateway_ip = t_subnet['gateway_ip']
+        if not t_gateway_ip:
+            # gateway is None, so we don't need to split allocation pools
+            return pools
         new_pools = NetworkHelper._split_pools_by_bottom_gateway_ip(
             pools, b_gateway_ip)
         if t_gateway_ip == b_gateway_ip:

tricircle/network/local_plugin.py

@@ -342,10 +342,14 @@ class TricirclePlugin(plugin.Ml2Plugin):
         return b_subnet
 
     def _create_bottom_subnet(self, t_ctx, q_ctx, t_subnet):
-        gateway_port = self._ensure_gateway_port(t_ctx, t_subnet)
+        if t_subnet['gateway_ip']:
+            gateway_port = self._ensure_gateway_port(t_ctx, t_subnet)
+            b_gateway_ip = gateway_port['fixed_ips'][0]['ip_address']
+        else:
+            b_gateway_ip = None
         subnet_body = helper.NetworkHelper.get_create_subnet_body(
-            gateway_port['tenant_id'], t_subnet, t_subnet['network_id'],
-            gateway_port['fixed_ips'][0]['ip_address'])['subnet']
+            t_subnet['tenant_id'], t_subnet, t_subnet['network_id'],
+            b_gateway_ip)['subnet']
         t_subnet['gateway_ip'] = subnet_body['gateway_ip']
         t_subnet['allocation_pools'] = subnet_body['allocation_pools']
 

tricircle/tempestplugin/smoke_test.sh

@@ -73,6 +73,16 @@ $openstackpod2 server create --flavor 1 --image $image2_id --nic net-id=$net2_id
 echo attach subnet2 to router
 $openstacktop router add subnet router subnet2
 
+echo create network4
+net4_id=$($openstacktop network create net4 -c id -f value)
+
+echo create subnet4 that has no gateway
+$openstacktop subnet create --subnet-range 10.0.4.0/24 --network net4 \
+    --gateway None subnet4
+
+echo create server3
+$openstackpod1 server create --flavor 1 --image $image1_id --nic net-id=$net4_id vm3
+
 sleep 20
 
 TOP_DIR=$DEVSTACK_DIR

tricircle/tempestplugin/smoke_test_validation.py

@@ -30,8 +30,10 @@ class ContainedString(object):
 
 
 CONDITIONS = {
-    '1': {'server': [{'Name': 'vm1', 'Status': 'ACTIVE'}],
-          'subnet': [{'Subnet': '100.0.0.0/24'}, {'Subnet': '10.0.1.0/24'}],
+    '1': {'server': [{'Name': 'vm1', 'Status': 'ACTIVE'},
+                     {'Name': 'vm3', 'Status': 'ACTIVE'}],
+          'subnet': [{'Subnet': '100.0.0.0/24'}, {'Subnet': '10.0.1.0/24'},
+                     {'Subnet': '10.0.4.0/24'}],
           'router_port': [{'Fixed IP Addresses': ContainedString('10.0.1')},
                           {'Fixed IP Addresses': ContainedString('100.0.0')}],
           'router': [

tricircle/tests/unit/network/test_local_plugin.py

@@ -337,15 +337,23 @@ class PluginTest(unittest.TestCase):
         def ip_to_digit(ip):
             return int(ip[ip.rindex('.') + 1:])
 
-        pool_range = list(range(ip_to_digit(t_gateway_ip),
-                                ip_to_digit(pool['end']) + 1))
-        # we include the top gateway ip in the bottom ip allocation pool
-        b_pool_range1 = list(range(ip_to_digit(b_pools[0]['start']),
-                                   ip_to_digit(b_pools[0]['end']) + 1))
-        b_pool_range2 = list(range(ip_to_digit(b_pools[1]['start']),
-                                   ip_to_digit(b_pools[1]['end']) + 1))
-        b_pool_range = b_pool_range1 + [
-            ip_to_digit(b_gateway_ip)] + b_pool_range2
+        if t_gateway_ip:
+            pool_range = list(range(ip_to_digit(t_gateway_ip),
+                                    ip_to_digit(pool['end']) + 1))
+            # we include the top gateway ip in the bottom ip allocation pool
+            b_pool_range1 = list(range(ip_to_digit(b_pools[0]['start']),
+                                       ip_to_digit(b_pools[0]['end']) + 1))
+            b_pool_range2 = list(range(ip_to_digit(b_pools[1]['start']),
+                                       ip_to_digit(b_pools[1]['end']) + 1))
+            b_pool_range = b_pool_range1 + [
+                ip_to_digit(b_gateway_ip)] + b_pool_range2
+        else:
+            self.assertIsNone(t_gateway_ip)
+            self.assertIsNone(b_gateway_ip)
+            pool_range = list(range(ip_to_digit(pool['start']),
+                                    ip_to_digit(pool['end'])))
+            b_pool_range = list(range(ip_to_digit(b_pools[0]['start']),
+                                      ip_to_digit(b_pools[0]['end'])))
         port.pop('name')
         b_port.pop('name')
         self.assertDictEqual(net, b_net)
@@ -376,6 +384,12 @@ class PluginTest(unittest.TestCase):
         t_net, t_subnet, t_port, _ = self._prepare_resource()
         self._validate(t_net, t_subnet, t_port)
 
+    @patch.object(t_context, 'get_context_from_neutron_context', new=mock.Mock)
+    def test_get_network_no_gateway(self):
+        t_net, t_subnet, t_port, _ = self._prepare_resource()
+        update_resource('subnet', True, t_subnet['id'], {'gateway_ip': None})
+        self._validate(t_net, t_subnet, t_port)
+
     @patch.object(t_context, 'get_context_from_neutron_context', new=mock.Mock)
     @patch.object(client.Client, 'get_admin_token', new=mock.Mock)
     def test_get_networks(self):