From d82fc3347da6106790b4b2bf24df667269188031 Mon Sep 17 00:00:00 2001
From: Alexander Kharkov <kharkovalexander@gmail.com>
Date: Thu, 3 Aug 2017 09:09:07 +0000
Subject: [PATCH] Implemented resume_state_on_host_boot driver callback

As result it is possible to use nova configuration option
'resume_guests_state_on_host_boot' option.
This option allow to keep instance RUNNING state across reboots
so if instance was in RUNNING state before reboot it will
started after reboot.

Change-Id: I884e0d1bf136488c1930673b25a560d0add12beb
Closes-Bug: 1708393
---
 nova/tests/unit/virt/lxd/test_driver.py | 17 +++++++++++++++++
 nova/virt/lxd/driver.py                 | 17 +++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/nova/tests/unit/virt/lxd/test_driver.py b/nova/tests/unit/virt/lxd/test_driver.py
index ed45e157..daaab781 100644
--- a/nova/tests/unit/virt/lxd/test_driver.py
+++ b/nova/tests/unit/virt/lxd/test_driver.py
@@ -922,6 +922,23 @@ class LXDDriverTest(test.NoDBTestCase):
         self.client.containers.get.assert_called_once_with(instance.name)
         container.unfreeze.assert_called_once_with(wait=True)
 
+    def test_resume_state_on_host_boot(self):
+        container = mock.Mock()
+        state = mock.Mock()
+        state.memory = dict({'usage': 0, 'usage_peak': 0})
+        state.status_code = 102
+        container.state.return_value = state
+        self.client.containers.get.return_value = container
+        ctx = context.get_admin_context()
+        instance = fake_instance.fake_instance_obj(
+            ctx, name='test', memory_mb=0)
+
+        lxd_driver = driver.LXDDriver(None)
+        lxd_driver.init_host(None)
+
+        lxd_driver.resume_state_on_host_boot(ctx, instance, None, None)
+        container.start.assert_called_once_with(wait=True)
+
     def test_rescue(self):
         profile = mock.Mock()
         profile.devices = {
diff --git a/nova/virt/lxd/driver.py b/nova/virt/lxd/driver.py
index d0b19e11..7e7473b3 100644
--- a/nova/virt/lxd/driver.py
+++ b/nova/virt/lxd/driver.py
@@ -797,6 +797,23 @@ class LXDDriver(driver.ComputeDriver):
         """
         self.unpause(instance)
 
+    def resume_state_on_host_boot(self, context, instance, network_info,
+                                  block_device_info=None):
+        """resume guest state when a host is booted."""
+        try:
+            state = self.get_info(instance).state
+            ignored_states = (power_state.RUNNING,
+                              power_state.SUSPENDED,
+                              power_state.NOSTATE,
+                              power_state.PAUSED)
+
+            if state in ignored_states:
+                return
+
+            self.power_on(context, instance, network_info, block_device_info)
+        except (exception.InternalError, exception.InstanceNotFound):
+            pass
+
     def rescue(self, context, instance, network_info, image_meta,
                rescue_password):
         """Rescue a LXD container.