Use mtu setting from table instead of flag

Adds mtu to argument lists of key methods and configuration of vlan
interface. Also adds deprecation notice to the "help" info for the file
based network_device_mtu configuration property.

Partially-implements blueprint better-support-for-multiple-networks

Change-Id: Ia401eb95ce8c81d104e59b0348e3474655b9a992

nova/network/linux_net.py

@@ -1269,12 +1269,14 @@ def _ip_bridge_cmd(action, params, device):
     return cmd
 
 
-def _set_device_mtu(dev):
+def _set_device_mtu(dev, mtu=None):
     """Set the device MTU."""
 
-    if CONF.network_device_mtu:
+    if not mtu:
+        mtu = CONF.network_device_mtu
+    if mtu:
         utils.execute('ip', 'link', 'set', dev, 'mtu',
-                      CONF.network_device_mtu, run_as_root=True,
+                      mtu, run_as_root=True,
                       check_exit_code=[0, 2, 254])
 
 
@@ -1418,7 +1420,8 @@ def plug(self, network, mac_address, gateway=True):
                            network['bridge'],
                            iface,
                            network,
-                           mac_address)
+                           mac_address,
+                           network.get('mtu'))
             iface = 'vlan%s' % vlan
         else:
             iface = CONF.flat_interface or network['bridge_interface']
@@ -1455,10 +1458,12 @@ def get_dev(self, network):
 
     @staticmethod
     def ensure_vlan_bridge(vlan_num, bridge, bridge_interface,
-                           net_attrs=None, mac_address=None):
+                           net_attrs=None, mac_address=None,
+                           mtu=None):
         """Create a vlan and bridge unless they already exist."""
         interface = LinuxBridgeInterfaceDriver.ensure_vlan(vlan_num,
-                                               bridge_interface, mac_address)
+                                               bridge_interface, mac_address,
+                                               mtu)
         LinuxBridgeInterfaceDriver.ensure_bridge(bridge, interface, net_attrs)
         return interface
 
@@ -1470,7 +1475,7 @@ def remove_vlan_bridge(vlan_num, bridge):
 
     @staticmethod
     @utils.synchronized('lock_vlan', external=True)
-    def ensure_vlan(vlan_num, bridge_interface, mac_address=None):
+    def ensure_vlan(vlan_num, bridge_interface, mac_address=None, mtu=None):
         """Create a vlan unless it already exists."""
         interface = 'vlan%s' % vlan_num
         if not device_exists(interface):
@@ -1487,7 +1492,9 @@ def ensure_vlan(vlan_num, bridge_interface, mac_address=None):
                          check_exit_code=[0, 2, 254])
             _execute('ip', 'link', 'set', interface, 'up', run_as_root=True,
                      check_exit_code=[0, 2, 254])
-            _set_device_mtu(interface)
+        # NOTE(vish): set mtu every time to ensure that changes to mtu get
+        #             propogated
+        _set_device_mtu(interface, mtu)
         return interface
 
     @staticmethod
@@ -1698,7 +1705,7 @@ def plug(self, network, mac_address, gateway=True):
                         'external-ids:attached-mac=%s' % mac_address])
             _execute('ip', 'link', 'set', dev, 'address', mac_address,
                      run_as_root=True)
-            _set_device_mtu(dev)
+            _set_device_mtu(dev, network.get('mtu'))
             _execute('ip', 'link', 'set', dev, 'up', run_as_root=True)
             if not gateway:
                 # If we weren't instructed to act as a gateway then add the

nova/objects/network.py

@@ -31,7 +31,8 @@
                      'for DHCP will be added on each nova-network node which '
                      'is only visible to the vms on the same host.'),
     cfg.IntOpt('network_device_mtu',
-               help='MTU setting for network interface'),
+               help='DEPRECATED: THIS VALUE SHOULD BE SET WHEN CREATING THE '
+                    'NETWORK. MTU setting for network interface.'),
 ]
 
 CONF = cfg.CONF

nova/tests/network/test_linux_net.py

@@ -520,7 +520,7 @@ def test_vlan_override(self):
         info = {}
 
         @staticmethod
-        def test_ensure(vlan, bridge, interface, network, mac_address):
+        def test_ensure(vlan, bridge, interface, network, mac_address, mtu):
             info['passed_interface'] = interface
 
         self.stubs.Set(linux_net.LinuxBridgeInterfaceDriver,