Merge "Set a default IP route metric in ip_lib.list_ip_routes"

neutron/agent/linux/ip_lib.py

@@ -76,6 +76,13 @@ DEFAULT_GW_PATTERN = re.compile(r"via (\S+)")
 METRIC_PATTERN = re.compile(r"metric (\S+)")
 DEVICE_NAME_PATTERN = re.compile(r"(\d+?): (\S+?):.*")
 
+# NOTE: no metric is interpreted by the kernel as having the highest priority
+# (value 0). "ip route" uses the netlink API to communicate with the kernel. In
+# IPv6, when the metric value is not set is translated as 1024 as default:
+# https://access.redhat.com/solutions/3659171
+IP_ROUTE_METRIC_DEFAULT = {constants.IP_VERSION_4: 0,
+                           constants.IP_VERSION_6: 1024}
+
 
 def remove_interface_suffix(interface):
     """Remove a possible "<if>@<endpoint>" suffix from an interface' name.
@@ -1501,6 +1508,8 @@ def list_ip_routes(namespace, ip_version, scope=None, via=None, table=None,
         else:
             cidr = constants.IP_ANY[ip_version]
         table = int(get_attr(route, 'RTA_TABLE'))
+        metric = (get_attr(route, 'RTA_PRIORITY') or
+                  IP_ROUTE_METRIC_DEFAULT[ip_version])
         value = {
             'table': IP_RULE_TABLES_NAMES.get(table, table),
             'source_prefix': get_attr(route, 'RTA_PREFSRC'),
@@ -1508,7 +1517,7 @@ def list_ip_routes(namespace, ip_version, scope=None, via=None, table=None,
             'scope': IP_ADDRESS_SCOPE[int(route['scope'])],
             'device': get_device(int(get_attr(route, 'RTA_OIF')), devices),
             'via': get_attr(route, 'RTA_GATEWAY'),
-            'metric': get_attr(route, 'RTA_PRIORITY'),
+            'metric': metric,
         }
 
         ret.append(value)

neutron/plugins/ml2/drivers/linuxbridge/agent/linuxbridge_neutron_agent.py

@@ -397,7 +397,8 @@ class LinuxBridgeManager(amb.CommonAgentManagerBase):
         if gateway:
             # Ensure that the gateway can be updated by changing the metric
             metric = 100
-            if 'metric' in gateway:
+            ip_version = utils.get_ip_version(gateway['cidr'])
+            if gateway['metric'] != ip_lib.IP_ROUTE_METRIC_DEFAULT[ip_version]:
                 metric = gateway['metric'] - 1
             dst_device.route.add_gateway(gateway=gateway['via'],
                                          metric=metric)

neutron/tests/functional/agent/linux/test_ip_lib.py

@@ -866,8 +866,8 @@ class IpRouteCommandTestCase(functional_base.BaseSudoTestCase):
             scope = ip_lib.IP_ADDRESS_SCOPE[0]
         elif not scope:
             scope = 'global' if via else 'link'
-        if ip_version == constants.IP_VERSION_6 and not metric:
-            metric = 1024
+        if not metric:
+            metric = ip_lib.IP_ROUTE_METRIC_DEFAULT[ip_version]
         table = table or iproute_linux.DEFAULT_TABLE
         table = ip_lib.IP_RULE_TABLES_NAMES.get(table, table)
         cmp = {'table': table,

neutron/tests/unit/plugins/ml2/drivers/linuxbridge/agent/test_linuxbridge_neutron_agent.py

@@ -471,7 +471,8 @@ class TestLinuxBridgeManager(base.BaseTestCase):
                 dv6_fn.assert_not_called()
 
     def test__update_interface_ip_details(self):
-        gwdict = dict(via='1.1.1.1',
+        gwdict = dict(cidr='1.1.1.1/24',
+                      via='1.1.1.1',
                       metric=50)
         ipdict = dict(cidr='1.1.1.1/24',
                       broadcast='1.1.1.255',