Create iproute.IPRoute() inside a context

IPRoute() object must be closed once is no longer used. This is done
automatically calling it inside its own context. If IPRoute() object
is not closed, the following error is raised after many calls:
  OSError: [Errno 24] Too many open files

Change-Id: I37ee291c22c2c3933ee229bfc939a4481898626c
Closes-Bug: #1807949

os_vif/internal/command/ip/linux/impl_pyroute2.py

@@ -40,61 +40,61 @@ class PyRoute2(ip_command.IpCommand):
     def set(self, device, check_exit_code=None, state=None, mtu=None,
             address=None, promisc=None):
         check_exit_code = check_exit_code or []
-        ip = iproute.IPRoute()
-        idx = ip.link_lookup(ifname=device)
-        if not idx:
-            raise exception.NetworkInterfaceNotFound(interface=device)
-        idx = idx[0]
+        with iproute.IPRoute() as ip:
+            idx = ip.link_lookup(ifname=device)
+            if not idx:
+                raise exception.NetworkInterfaceNotFound(interface=device)
+            idx = idx[0]
 
-        args = {'index': idx}
-        if state:
-            args['state'] = state
-        if mtu:
-            args['mtu'] = mtu
-        if address:
-            args['address'] = address
-        if promisc is not None:
-            flags = ip.link('get', index=idx)[0]['flags']
-            args['flags'] = (utils.set_mask(flags, ifinfmsg.IFF_PROMISC)
-                             if promisc is True else
-                             utils.unset_mask(flags, ifinfmsg.IFF_PROMISC))
+            args = {'index': idx}
+            if state:
+                args['state'] = state
+            if mtu:
+                args['mtu'] = mtu
+            if address:
+                args['address'] = address
+            if promisc is not None:
+                flags = ip.link('get', index=idx)[0]['flags']
+                args['flags'] = (utils.set_mask(flags, ifinfmsg.IFF_PROMISC)
+                                 if promisc is True else
+                                 utils.unset_mask(flags, ifinfmsg.IFF_PROMISC))
 
-        if isinstance(check_exit_code, int):
-            check_exit_code = [check_exit_code]
+            if isinstance(check_exit_code, int):
+                check_exit_code = [check_exit_code]
 
-        return self._ip_link(ip, 'set', check_exit_code, **args)
+            return self._ip_link(ip, 'set', check_exit_code, **args)
 
     def add(self, device, dev_type, check_exit_code=None, peer=None, link=None,
             vlan_id=None):
         check_exit_code = check_exit_code or []
-        ip = iproute.IPRoute()
-        args = {'ifname': device,
-                '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]
-        elif self.TYPE_VETH == dev_type:
-            args['peer'] = peer
-        else:
-            raise exception.NetworkInterfaceTypeNotDefined(type=dev_type)
+        with iproute.IPRoute() as ip:
+            args = {'ifname': device,
+                    '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]
+            elif self.TYPE_VETH == dev_type:
+                args['peer'] = peer
+            else:
+                raise exception.NetworkInterfaceTypeNotDefined(type=dev_type)
 
-        return self._ip_link(ip, 'add', check_exit_code, **args)
+            return self._ip_link(ip, 'add', check_exit_code, **args)
 
     def delete(self, device, check_exit_code=None):
         check_exit_code = check_exit_code or []
-        ip = iproute.IPRoute()
-        idx = ip.link_lookup(ifname=device)
-        if len(idx) == 0:
-            raise exception.NetworkInterfaceNotFound(interface=device)
-        idx = idx[0]
+        with iproute.IPRoute() as ip:
+            idx = ip.link_lookup(ifname=device)
+            if len(idx) == 0:
+                raise exception.NetworkInterfaceNotFound(interface=device)
+            idx = idx[0]
 
-        return self._ip_link(ip, 'del', check_exit_code, **{'index': idx})
+            return self._ip_link(ip, 'del', check_exit_code, **{'index': idx})
 
     def exists(self, device):
         """Return True if the device exists."""
-        ip = iproute.IPRoute()
-        idx = ip.link_lookup(ifname=device)
-        return True if idx else False
+        with iproute.IPRoute() as ip:
+            idx = ip.link_lookup(ifname=device)
+            return True if idx else False

os_vif/tests/functional/internal/command/ip/test_impl_pyroute2.py

@@ -181,3 +181,13 @@ class TestIpCommand(ShellIpCommands, base.BaseFunctionalTestCase):
         self.assertTrue(self.exist_device(device))
         _ip_cmd_delete(device)
         self.assertFalse(self.exist_device(device))
+
+    def test_iproute_object_closes_correctly(self):
+        # NOTE(ralonsoh): check https://bugs.launchpad.net/os-vif/+bug/1807949
+        device = "test_dev_9"
+        link = "test_devlink_2"
+        self.add_device(link, 'dummy')
+        self.addCleanup(self.del_device, 'dummy')
+        for _ in range(300):
+            _ip_cmd_add(device, 'vlan', link=link, vlan_id=100)
+            _ip_cmd_delete(device)