update the logic for calculating network sizes

2 files changed, 31 insertions, 5 deletions

diff --git a/nova/compute/network.py b/nova/compute/network.py
index bdb8a22f9..43011f696 100644
--- a/nova/compute/network.py
+++ b/nova/compute/network.py
@@ -162,6 +162,7 @@ class Vlan(datastore.BasicModel):
 
 class BaseNetwork(datastore.BasicModel):
     override_type = 'network'
+    NUM_STATIC_IPS = 3 # Network, Gateway, and CloudPipe
 
     @property
     def identifier(self):
@@ -237,11 +238,15 @@ class BaseNetwork(datastore.BasicModel):
     def available(self):
         # the .2 address is always CloudPipe
         # and the top <n> are for vpn clients
-        for idx in range(3, len(self.network)-(1 + FLAGS.cnt_vpn_clients)):
+        for idx in range(self.num_static_ips, len(self.network)-(1 + FLAGS.cnt_vpn_clients)):
             address = str(self.network[idx])
             if not address in self.hosts.keys():
                 yield str(address)
 
+    @property
+    def num_static_ips(self):
+        return BaseNetwork.NUM_STATIC_IPS
+
     def allocate_ip(self, user_id, project_id, mac):
         for address in self.available:
             logging.debug("Allocating IP %s to %s" % (address, project_id))
diff --git a/nova/tests/network_unittest.py b/nova/tests/network_unittest.py
index 444063d0f..f3a5868d1 100644
--- a/nova/tests/network_unittest.py
+++ b/nova/tests/network_unittest.py
@@ -147,21 +147,42 @@ class NetworkTestCase(test.TrialTestCase):
 
     def test_too_many_addresses(self):
         """
-        Network size is 32, there are 5 addresses reserved for VPN.
-        So we should get 23 usable addresses
+        Here, we test that a proper NoMoreAddresses exception is raised.
+
+        However, the number of available IP addresses depends on the test
+        environment's setup.
+
+        Network size is set in test fixture's setUp method.
+            
+        There are FLAGS.cnt_vpn_clients addresses reserved for VPN (NUM_RESERVED_VPN_IPS)
+
+        And there are NUM_STATIC_IPS that are always reserved by Nova for the necessary
+        services (gateway, CloudPipe, etc)
+
+        So we should get flags.network_size - (NUM_STATIC_IPS + 
+                                               NUM_PREALLOCATED_IPS + 
+                                               NUM_RESERVED_VPN_IPS)
+        usable addresses
         """
         net = network.get_project_network("project0", "default")
+
+        # Determine expected number of available IP addresses
+        num_static_ips = net.num_static_ips
+        num_preallocated_ips = len(net.hosts.keys())
+        num_reserved_vpn_ips = flags.FLAGS.cnt_vpn_clients
+        num_available_ips = flags.FLAGS.network_size - (num_static_ips + num_preallocated_ips + num_reserved_vpn_ips)
+
         hostname = "toomany-hosts"
         macs = {}
         addresses = {}
-        for i in range(0, 22):
+        for i in range(0, (num_available_ips - 1)):
             macs[i] = utils.generate_mac()
             addresses[i] = network.allocate_ip("netuser", "project0", macs[i])
             self.dnsmasq.issue_ip(macs[i], addresses[i], hostname, net.bridge_name)
 
         self.assertRaises(NoMoreAddresses, network.allocate_ip, "netuser", "project0", utils.generate_mac())
 
-        for i in range(0, 22):
+        for i in range(0, (num_available_ips - 1)):
             rv = network.deallocate_ip(addresses[i])
             self.dnsmasq.release_ip(macs[i], addresses[i], hostname, net.bridge_name)