Switch IPDevice.exists() method to use pyroute2

Check if network device exists is now done by checking
interface index with pyroute2 interface instead of checking
if MAC address for device is set.

Change-Id: I2d5b95ec109fb19fc2a46c1017959f74011b9a22
Related-Bug: #1492714

neutron/agent/linux/ip_lib.py

@@ -294,15 +294,7 @@ class IPDevice(SubProcessBase):
 
     def exists(self):
         """Return True if the device exists in the namespace."""
-        # we must save and restore this before returning
+        return privileged.interface_exists(self.name, self.namespace)
-        orig_log_fail_as_error = self.get_log_fail_as_error()
-        self.set_log_fail_as_error(False)
-        try:
-            return bool(self.link.address)
-        except RuntimeError:
-            return False
-        finally:
-            self.set_log_fail_as_error(orig_log_fail_as_error)
 
     def delete_addr_and_conntrack_state(self, cidr):
         """Delete an address along with its conntrack state

neutron/cmd/linuxbridge_cleanup.py

@@ -16,7 +16,7 @@ from neutron_lib.utils import helpers
 from oslo_config import cfg
 from oslo_log import log as logging
 
-from neutron.common import config
+from neutron.conf.agent import common as config
 from neutron.plugins.ml2.drivers.linuxbridge.agent \
     import linuxbridge_neutron_agent
 
@@ -69,4 +69,5 @@ def main():
     """
     cfg.CONF(sys.argv[1:])
     config.setup_logging()
+    config.setup_privsep()
     remove_empty_bridges()

neutron/privileged/agent/linux/ip_lib.py

@@ -194,6 +194,19 @@ def delete_interface(ifname, namespace, **kwargs):
     _run_iproute_link("del", ifname, namespace, **kwargs)
 
 
+@privileged.default.entrypoint
+def interface_exists(ifname, namespace):
+    try:
+        idx = _get_link_id(ifname, namespace)
+        return bool(idx)
+    except NetworkInterfaceNotFound:
+        return False
+    except OSError as e:
+        if e.errno == errno.ENOENT:
+            return False
+        raise
+
+
 @privileged.default.entrypoint
 def add_neigh_entry(ip_version, ip_address, mac_address, device, namespace,
                     **kwargs):

neutron/tests/base.py

@@ -112,6 +112,14 @@ def unstable_test(reason):
     return decor
 
 
+def get_rootwrap_cmd():
+    return os.environ.get('OS_ROOTWRAP_CMD', SUDO_CMD)
+
+
+def get_rootwrap_daemon_cmd():
+    return os.environ.get('OS_ROOTWRAP_DAEMON_CMD')
+
+
 class AttributeDict(dict):
 
     """
@@ -424,10 +432,9 @@ class BaseTestCase(DietTestCase):
     def setup_rootwrap(self):
         agent_config.register_root_helper(cfg.CONF)
         self.config(group='AGENT',
-                    root_helper=os.environ.get('OS_ROOTWRAP_CMD', SUDO_CMD))
+                    root_helper=get_rootwrap_cmd())
         self.config(group='AGENT',
-                    root_helper_daemon=os.environ.get(
+                    root_helper_daemon=get_rootwrap_daemon_cmd())
-                        'OS_ROOTWRAP_DAEMON_CMD'))
 
 
 class PluginFixture(fixtures.Fixture):

neutron/tests/functional/cmd/test_linuxbridge_cleanup.py

@@ -20,6 +20,7 @@ from neutron_lib import constants
 from neutron.agent.linux import ip_lib
 from neutron.plugins.ml2.drivers.linuxbridge.agent import \
     linuxbridge_neutron_agent as lb_agent
+from neutron.tests import base as tests_base
 from neutron.tests.common import config_fixtures
 from neutron.tests.common import net_helpers
 from neutron.tests.functional import base
@@ -35,6 +36,16 @@ class LinuxbridgeCleanupTest(base.BaseSudoTestCase):
                     prefix=lb_agent.BRIDGE_NAME_PREFIX))).fixture
 
         config = callback(br_fixture)
+        # NOTE(slaweq): use of oslo.privsep inside neutron-linuxbridge-cleanup
+        # script requires rootwrap helper to be configured in this script's
+        # config
+        config.update({
+            'AGENT': {
+                'root_helper': tests_base.get_rootwrap_cmd(),
+                'root_helper_daemon': tests_base.get_rootwrap_daemon_cmd()
+            }
+        })
+
         config.update({'VXLAN': {'enable_vxlan': 'False'}})
 
         temp_dir = self.useFixture(fixtures.TempDir()).path

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

@@ -1383,28 +1383,6 @@ class TestIpNetnsCommand(TestIPCmdBase):
 
 
 class TestDeviceExists(base.BaseTestCase):
-    def test_device_exists(self):
-        with mock.patch('neutron.agent.common.utils.execute') as execute:
-            execute.return_value = LINK_SAMPLE[1]
-            self.assertTrue(ip_lib.device_exists('eth0'))
-            execute.assert_called_once_with(
-                ['ip', '-o', 'link', 'show', 'eth0'],
-                run_as_root=False, log_fail_as_error=False)
-
-    def test_device_exists_reset_fail(self):
-        device = ip_lib.IPDevice('eth0')
-        device.set_log_fail_as_error(True)
-        with mock.patch.object(ip_lib.IPDevice, '_execute') as _execute:
-            _execute.return_value = LINK_SAMPLE[1]
-            self.assertTrue(device.exists())
-            self.assertTrue(device.get_log_fail_as_error())
-
-    def test_device_does_not_exist(self):
-        with mock.patch.object(ip_lib.IPDevice, '_execute') as _execute:
-            _execute.return_value = ''
-            _execute.side_effect = RuntimeError
-            self.assertFalse(ip_lib.device_exists('eth0'))
-
     def test_ensure_device_is_ready(self):
         ip_lib_mock = mock.Mock()
         with mock.patch.object(ip_lib, 'IPDevice', return_value=ip_lib_mock):