support pyroute2 0.5.13

This change modifes os-vif add interface to account
for the new behavior of link_lookup.
In 0.5.13 if a link is not found link_lookup returns an
empty list. In previous releases it raised ipexc.NetlinkError.

Closes-bug: #1890353

Change-Id: I567afb544425c1b91d98968a0b597be718869089

os_vif/internal/ip/linux/impl_pyroute2.py

@@ -41,11 +41,7 @@ class PyRoute2(ip_command.IpCommand):
             address=None, promisc=None, master=None):
         check_exit_code = check_exit_code or []
         with iproute.IPRoute() as ip:
-            idx = ip.link_lookup(ifname=device)
-            if not idx:
-                raise exception.NetworkInterfaceNotFound(interface=device)
-            idx = idx[0]
-
+            idx = self.lookup_interface(ip, device)
             args = {'index': idx}
             if state:
                 args['state'] = state
@@ -59,13 +55,24 @@ class PyRoute2(ip_command.IpCommand):
                                  if promisc is True else
                                  utils.unset_mask(flags, ifinfmsg.IFF_PROMISC))
             if master:
-                args['master'] = ip.link_lookup(ifname=master)
+                args['master'] = self.lookup_interface(ip, master)
 
             if isinstance(check_exit_code, int):
                 check_exit_code = [check_exit_code]
 
             return self._ip_link(ip, 'set', check_exit_code, **args)
 
+    def lookup_interface(self, ip, link):
+        # TODO(sean-k-mooney): remove try block after we raise
+        # the min pyroute2 version above 0.5.12
+        try:
+            idx = ip.link_lookup(ifname=link)
+        except ipexc.NetlinkError:
+            raise exception.NetworkInterfaceNotFound(interface=link)
+        if not len(idx):
+            raise exception.NetworkInterfaceNotFound(interface=link)
+        return idx[0]
+
     def add(self, device, dev_type, check_exit_code=None, peer=None, link=None,
             vlan_id=None, ageing=None):
         check_exit_code = check_exit_code or []
@@ -74,10 +81,7 @@ class PyRoute2(ip_command.IpCommand):
                     'kind': dev_type}
             if self.TYPE_VLAN == dev_type:
                 args['vlan_id'] = vlan_id
-                idx = ip.link_lookup(ifname=link)
-                if 0 == len(idx):
-                    raise exception.NetworkInterfaceNotFound(interface=link)
-                args['link'] = idx[0]
+                args['link'] = self.lookup_interface(ip, link)
             elif self.TYPE_VETH == dev_type:
                 args['peer'] = peer
             elif self.TYPE_BRIDGE == dev_type:
@@ -106,15 +110,14 @@ class PyRoute2(ip_command.IpCommand):
     def delete(self, device, check_exit_code=None):
         check_exit_code = check_exit_code or []
         with iproute.IPRoute() as ip:
-            idx = ip.link_lookup(ifname=device)
-            if len(idx) == 0:
-                raise exception.NetworkInterfaceNotFound(interface=device)
-            idx = idx[0]
-
+            idx = self.lookup_interface(ip, device)
             return self._ip_link(ip, 'del', check_exit_code, **{'index': idx})
 
     def exists(self, device):
         """Return True if the device exists."""
         with iproute.IPRoute() as ip:
-            idx = ip.link_lookup(ifname=device)
-            return True if idx else False
+            try:
+                self.lookup_interface(ip, device)
+                return True
+            except Exception:
+                return False

os_vif/tests/unit/internal/ip/linux/test_impl_pyroute2.py

@@ -134,9 +134,11 @@ class TestIpCommand(base.TestCase):
         self.ip_link.assert_called_once_with(
             'add', ifname=self.DEVICE, kind=self.TYPE_VETH, peer='peer')
 
-        self.assertRaises(ipexc.NetlinkError, self.ip.add, self.DEVICE,
-                          self.TYPE_VLAN, peer='peer',
-                          check_exit_code=[self.OTHER_ERROR_CODE])
+        self.assertRaises(
+            exception.NetworkInterfaceNotFound,
+            self.ip.add, self.DEVICE,
+            self.TYPE_VLAN, peer='peer',
+            check_exit_code=[self.OTHER_ERROR_CODE])
 
     def test_delete(self):
         with mock.patch.object(iproute.IPRoute, 'link_lookup',