Merge "Gracefully restart dnsmasq to not break tcp DNS"

neutron/agent/linux/dhcp.py

@@ -21,6 +21,7 @@ import itertools
 import os
 import re
 import shutil
+import signal
 import time
 
 import netaddr
@@ -45,6 +46,7 @@ from neutron.ipam import utils as ipam_utils
 from neutron.privileged.agent.linux import dhcp as priv_dhcp
 
 LOG = logging.getLogger(__name__)
+SIGTERM_TIMEOUT = 5
 
 DNS_PORT = 53
 WIN2k3_STATIC_DNS = 249
@@ -349,9 +351,18 @@ class DhcpLocalProcess(DhcpBase, metaclass=abc.ABCMeta):
     def disable(self, retain_port=False, block=False):
         """Disable DHCP for this network by killing the local process."""
         self.process_monitor.unregister(self.network.id, DNSMASQ_SERVICE_NAME)
-        self._get_process_manager().disable()
+        pm = self._get_process_manager()
+        pm.disable(sig=str(int(signal.SIGTERM)))
         if block:
-            common_utils.wait_until_true(lambda: not self.active)
+            try:
+                common_utils.wait_until_true(lambda: not self.active,
+                                             timeout=SIGTERM_TIMEOUT)
+            except common_utils.WaitTimeout:
+                LOG.warning('dnsmasq process %s did not finish after SIGTERM '
+                            'signal in %s seconds, sending SIGKILL signal',
+                            pm.pid, SIGTERM_TIMEOUT)
+                pm.disable(sig=str(int(signal.SIGKILL)))
+                common_utils.wait_until_true(lambda: not self.active)
         self._del_running_interface(self.interface_name)
         if not retain_port:
             self._destroy_namespace_and_port()

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

@@ -15,6 +15,7 @@
 
 import copy
 import os
+import signal
 from unittest import mock
 
 import netaddr
@@ -32,6 +33,7 @@ import testtools
 from neutron.agent.linux import dhcp
 from neutron.agent.linux import ip_lib
 from neutron.cmd import runtime_checks as checks
+from neutron.common import utils as common_utils
 from neutron.conf.agent import common as config
 from neutron.conf.agent import dhcp as dhcp_config
 from neutron.conf import common as base_config
@@ -1272,6 +1274,36 @@ class TestDhcpLocalProcess(TestBase):
         parent.assert_has_calls(expected)
         delete_ns.assert_called_with('qdhcp-ns')
 
+    @mock.patch.object(common_utils, 'wait_until_true')
+    def test_disable_blocking(self, mock_wait_until):
+        lp = LocalChild(self.conf, FakeDualNetwork())
+        mock_pm = mock.Mock()
+        with mock.patch('neutron.agent.linux.ip_lib.'
+                        'delete_network_namespace'), \
+                mock.patch.object(dhcp.DhcpLocalProcess,
+                                  '_get_process_manager',
+                                  return_value=mock_pm):
+            lp.disable(block=True)
+        self.assertEqual(1, mock_wait_until.call_count)
+        mock_pm.disable.assert_called_once_with(sig=str(int(signal.SIGTERM)))
+
+    @mock.patch.object(common_utils, 'wait_until_true')
+    def test_disable_blocking_sigterm_sigkill(self, mock_wait_until):
+        mock_wait_until.side_effect = [common_utils.WaitTimeout, None]
+
+        lp = LocalChild(self.conf, FakeDualNetwork())
+        mock_pm = mock.Mock()
+        with mock.patch('neutron.agent.linux.ip_lib.'
+                        'delete_network_namespace'), \
+                mock.patch.object(dhcp.DhcpLocalProcess,
+                                  '_get_process_manager',
+                                  return_value=mock_pm):
+            lp.disable(block=True)
+        self.assertEqual(2, mock_wait_until.call_count)
+        mock_pm.disable.assert_has_calls([
+            mock.call(sig=str(int(signal.SIGTERM))),
+            mock.call(sig=str(int(signal.SIGKILL)))])
+
     def test_get_interface_name(self):
         net = FakeDualNetwork()
         path = '/dhcp/%s/interface' % net.id