Merge "Allow to configure DHCP T1 and T2 timers in dnsmasq"

neutron/agent/linux/dhcp.py

@@ -403,6 +403,14 @@ class Dnsmasq(DhcpLocalProcess):
         cmd.append('--dhcp-lease-max=%d' %
                    min(possible_leases, self.conf.dnsmasq_lease_max))
 
+        if self.conf.dhcp_renewal_time > 0:
+            cmd.append('--dhcp-option-force=option:T1,%ds' %
+                       self.conf.dhcp_renewal_time)
+
+        if self.conf.dhcp_rebinding_time > 0:
+            cmd.append('--dhcp-option-force=option:T2,%ds' %
+                       self.conf.dhcp_rebinding_time)
+
         cmd.append('--conf-file=%s' % self.conf.dnsmasq_config_file)
         for server in self.conf.dnsmasq_dns_servers:
             cmd.append('--server=%s' % server)

neutron/conf/agent/dhcp.py

@@ -94,6 +94,12 @@ DNSMASQ_OPTS = [
         help=_('Limit number of leases to prevent a denial-of-service.')),
     cfg.BoolOpt('dhcp_broadcast_reply', default=False,
                 help=_("Use broadcast in DHCP replies.")),
+    cfg.IntOpt('dhcp_renewal_time', default=0,
+               help=_("DHCP renewal time T1 (in seconds). If set to 0, it "
+                      "will default to half of the lease time.")),
+    cfg.IntOpt('dhcp_rebinding_time', default=0,
+               help=_("DHCP rebinding time T2 (in seconds). If set to 0, it "
+                      "will default to 7/8 of the lease time.")),
 ]
 
 

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

@@ -1173,7 +1173,7 @@ class TestDnsmasq(TestBase):
     def _test_spawn(self, extra_options, network=FakeDualNetwork(),
                     max_leases=16777216, lease_duration=86400,
                     has_static=True, no_resolv='--no-resolv',
-                    has_stateless=True):
+                    has_stateless=True, dhcp_t1=0, dhcp_t2=0):
         def mock_get_conf_file_name(kind):
             return '/dhcp/%s/%s' % (network.id, kind)
 
@@ -1230,6 +1230,11 @@ class TestDnsmasq(TestBase):
 
         expected.append('--dhcp-lease-max=%d' % min(
             possible_leases, max_leases))
+
+        if dhcp_t1:
+            expected.append('--dhcp-option-force=option:T1,%ds' % dhcp_t1)
+        if dhcp_t2:
+            expected.append('--dhcp-option-force=option:T2,%ds' % dhcp_t2)
         expected.extend(extra_options)
 
         self.execute.return_value = ('', '')
@@ -1361,6 +1366,12 @@ class TestDnsmasq(TestBase):
         self._test_spawn(['--conf-file=', '--domain=openstacklocal'],
                          network)
 
+    def test_spawn_cfg_with_dhcp_timers(self):
+        self.conf.set_override('dhcp_renewal_time', 30)
+        self.conf.set_override('dhcp_rebinding_time', 100)
+        self._test_spawn(['--conf-file=', '--domain=openstacklocal'],
+                         dhcp_t1=30, dhcp_t2=100)
+
     def _test_output_init_lease_file(self, timestamp):
         expected = [
             '00:00:80:aa:bb:cc 192.168.0.2 * *',

releasenotes/notes/add_dhcp_dnsmasq_t1t2_options-3cef427d8109c165.yaml

@@ -0,0 +1,11 @@
+---
+features:
+  - |
+    Allow configuration of DHCP renewal (T1) and rebinding (T2) timers in
+    ``neutron-dhcp-agent``. By allowing these timers to be set (options 58
+    and 59 as per RFC2132) in ``dnsmasq`` it allows users to change
+    other parameters, like MTU, on instances without having to wait for
+    the lease time to expire. The advantage of changing T1 over the
+    lease time is that if the DHCP server becomes unreachable within
+    the lease time, instances will not drop their IP addresses and it
+    will not cause a dataplane disruption.