From ae3bb03699a4e27b8aafe31837180ca168efab49 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=89douard=20Thuleau?= <edouard.thuleau@orange.com>
Date: Tue, 4 Dec 2012 17:06:23 +0100
Subject: [PATCH] Periodic update of DNS entries.

The new DNS mechanism to resolve instance names on private network with
multi hosted mode doesn't scale.
This patch add the possibility to update the DNS entries periodically on
each network host in addition to fanout cast each time the DNS entries
need to be updated.

DocImpact: new config options
Fixes LP bug #1086026

Change-Id: I59094a29c9f5010f5e55a6f11160263337b058b2
---
 etc/nova/nova.conf.sample |  9 +++++++++
 nova/network/manager.py   | 13 +++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/etc/nova/nova.conf.sample b/etc/nova/nova.conf.sample
index 2fdd612b46e9..c3c10239c6da 100644
--- a/etc/nova/nova.conf.sample
+++ b/etc/nova/nova.conf.sample
@@ -920,6 +920,15 @@
 # l3_lib=nova.network.l3.LinuxNetL3
 #### (StrOpt) Indicates underlying L3 management library
 
+# update_dns_entries=false
+#### (BoolOpt) If True, when a DNS entry must be updated, it sends a fanout
+####           cast to all network hosts to update their DNS entries in multi
+####           host mode
+
+# dns_update_periodic_interval=-1
+#### (IntOpt) Number of periodic scheduler ticks to wait between runs of
+####          updates to DNS entries
+
 
 ######## defined in nova.network.quantumv2.api ########
 
diff --git a/nova/network/manager.py b/nova/network/manager.py
index 97d4fa10d341..f4d45d8eecee 100644
--- a/nova/network/manager.py
+++ b/nova/network/manager.py
@@ -170,6 +170,10 @@ network_opts = [
                 help='If True, when a DNS entry must be updated, it sends a '
                      'fanout cast to all network hosts to update their DNS '
                      'entries in multi host mode'),
+    cfg.IntOpt("dns_update_periodic_interval",
+               default=-1,
+               help='Number of periodic scheduler ticks to wait between '
+                    'runs of updates to DNS entries.'),
     cfg.StrOpt('dhcp_domain',
                default='novalocal',
                help='domain to use for building the hostnames'),
@@ -1943,6 +1947,15 @@ class NetworkManager(manager.SchedulerDependentManager):
         return self.db.virtual_interface_get_by_address(context,
                                                         mac_address)
 
+    @manager.periodic_task(
+        ticks_between_runs=CONF.dns_update_periodic_interval)
+    def _periodic_update_dns(self, context):
+        """Update local DNS entries of all networks on this host"""
+        networks = self.db.network_get_all_by_host(context, self.host)
+        for network in networks:
+            dev = self.driver.get_dev(network)
+            self.driver.update_dns(context, dev, network)
+
     def update_dns(self, context, network_ids):
         """Called when fixed IP is allocated or deallocated"""
         if CONF.fake_network: