From 6548c509f1780a7168f26de6f2045ec7d5768520 Mon Sep 17 00:00:00 2001
From: Dan Prince <dprince@redhat.com>
Date: Fri, 1 Jun 2012 10:34:11 -0400
Subject: Implements resume_state_on_host_boot for libvirt.

Adds a new virt driver function to help resume guest states
on host boot. This fixes a couple issue with using a reboot
(like we did previously):

 * Using reboot would clear some task states (VERIFY_RESIZE for example)
 * Provides a mechanism for hypervisor specific guest restarts.
   Reboot would not have worked for XenServer for example...
 * Updates libvirt to use a hard reboot (instead of soft)

Fixes LP Bug #985162.

Change-Id: Iaf5aad75ec9b91f44710a18ddaf3a93378573a62
---
 nova/compute/manager.py         | 10 ++++++++--
 nova/tests/test_virt_drivers.py |  6 ++++++
 nova/virt/driver.py             |  4 ++++
 nova/virt/fake.py               |  3 +++
 nova/virt/libvirt/connection.py |  7 +++++++
 5 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/nova/compute/manager.py b/nova/compute/manager.py
index fde9e0e4c..6cbfdd846 100644
--- a/nova/compute/manager.py
+++ b/nova/compute/manager.py
@@ -287,15 +287,21 @@ class ComputeManager(manager.SchedulerDependentManager):
             LOG.debug(_('Current state is %(drv_state)s, state in DB is '
                         '%(db_state)s.'), locals(), instance=instance)
 
+            net_info = self._get_instance_nw_info(context, instance)
             if ((expect_running and FLAGS.resume_guests_state_on_host_boot) or
                 FLAGS.start_guests_on_host_boot):
                 LOG.info(_('Rebooting instance after nova-compute restart.'),
                          locals(), instance=instance)
-                self.reboot_instance(context, instance['uuid'])
+                try:
+                    self.driver.resume_state_on_host_boot(context, instance,
+                                self._legacy_nw_info(net_info))
+                except NotImplementedError:
+                    LOG.warning(_('Hypervisor driver does not support '
+                                  'resume guests'), instance=instance)
+
             elif drv_state == power_state.RUNNING:
                 # VMWareAPI drivers will raise an exception
                 try:
-                    net_info = self._get_instance_nw_info(context, instance)
                     self.driver.ensure_filtering_rules_for_instance(instance,
                                                 self._legacy_nw_info(net_info))
                 except NotImplementedError:
diff --git a/nova/tests/test_virt_drivers.py b/nova/tests/test_virt_drivers.py
index 95990cee5..917adc0dd 100644
--- a/nova/tests/test_virt_drivers.py
+++ b/nova/tests/test_virt_drivers.py
@@ -137,6 +137,12 @@ class _VirtDriverTestCase(test.TestCase):
         self.connection.agent_update(instance_ref, 'http://www.openstack.org/',
                                      'd41d8cd98f00b204e9800998ecf8427e')
 
+    @catch_notimplementederror
+    def test_resume_state_on_host_boot(self):
+        instance_ref, network_info = self._get_running_instance()
+        self.connection.resume_state_on_host_boot(self.ctxt, instance_ref,
+                                                  network_info)
+
     @catch_notimplementederror
     def test_rescue(self):
         instance_ref, network_info = self._get_running_instance()
diff --git a/nova/virt/driver.py b/nova/virt/driver.py
index 895a32ed3..f7dfbf7cd 100644
--- a/nova/virt/driver.py
+++ b/nova/virt/driver.py
@@ -326,6 +326,10 @@ class ComputeDriver(object):
         # TODO(Vek): Need to pass context in for access to auth_token
         raise NotImplementedError()
 
+    def resume_state_on_host_boot(self, context, instance, network_info):
+        """resume guest state when a host is booted"""
+        raise NotImplementedError()
+
     def rescue(self, context, instance, network_info, image_meta):
         """Rescue the specified instance"""
         raise NotImplementedError()
diff --git a/nova/virt/fake.py b/nova/virt/fake.py
index 57c358521..36d37e0cd 100644
--- a/nova/virt/fake.py
+++ b/nova/virt/fake.py
@@ -128,6 +128,9 @@ class FakeConnection(driver.ComputeDriver):
     def agent_update(self, instance, url, md5hash):
         pass
 
+    def resume_state_on_host_boot(self, context, instance, network_info):
+        pass
+
     def rescue(self, context, instance, network_info, image_meta):
         pass
 
diff --git a/nova/virt/libvirt/connection.py b/nova/virt/libvirt/connection.py
index ab32ff927..dedc86ca4 100644
--- a/nova/virt/libvirt/connection.py
+++ b/nova/virt/libvirt/connection.py
@@ -811,6 +811,13 @@ class LibvirtConnection(driver.ComputeDriver):
         dom = self._lookup_by_name(instance.name)
         dom.create()
 
+    @exception.wrap_exception()
+    def resume_state_on_host_boot(self, context, instance, network_info):
+        """resume guest state when a host is booted"""
+        # NOTE(dprince): use hard reboot to ensure network and firewall
+        # rules are configured
+        self._hard_reboot(instance, network_info)
+
     @exception.wrap_exception()
     def rescue(self, context, instance, network_info, image_meta):
         """Loads a VM using rescue images.
-- 
cgit