If rescue fails don't error the instance

If a rescue attempt fails, the VM's state should return to what it was
before the rescue attempt started, and the user should be notified of
the failure.

Fixes bug: 1170328

Change-Id: If5e97d06a3617adad83a4bba2ac6320616bbe83b

1 files changed, 28 insertions, 0 deletions

diff --git a/nova/tests/compute/test_compute.py b/nova/tests/compute/test_compute.py
index 6bf612eee..e3db2cdba 100644
--- a/nova/tests/compute/test_compute.py
+++ b/nova/tests/compute/test_compute.py
@@ -22,6 +22,7 @@ import base64
 import copy
 import datetime
 import sys
+import testtools
 import time
 import traceback
 import uuid
@@ -1265,6 +1266,33 @@ class ComputeTestCase(BaseTestCase):
 
         self.compute.terminate_instance(self.context, instance=instance)
 
+    def test_rescue_handle_err(self):
+        # If the driver fails to rescue, instance state should remain the same
+        # and the exception should be converted to InstanceNotRescuable
+        instance = jsonutils.to_primitive(self._create_fake_instance())
+        self.mox.StubOutWithMock(self.compute, '_get_rescue_image_ref')
+        self.mox.StubOutWithMock(nova.virt.fake.FakeDriver, 'rescue')
+
+        self.compute._get_rescue_image_ref(
+            mox.IgnoreArg(), instance).AndReturn('resc_image_ref')
+        nova.virt.fake.FakeDriver.rescue(
+            mox.IgnoreArg(), instance, [], mox.IgnoreArg(), 'password'
+            ).AndRaise(RuntimeError("Try again later"))
+
+        self.mox.ReplayAll()
+
+        expected_message = ('Instance %s cannot be rescued: '
+                            'Driver Error: Try again later' % instance['uuid'])
+        instance['vm_state'] = 'some_random_state'
+
+        with testtools.ExpectedException(
+            exception.InstanceNotRescuable, expected_message):
+                self.compute.rescue_instance(
+                    self.context, instance=instance,
+                    rescue_password='password')
+
+        self.assertEqual('some_random_state', instance['vm_state'])
+
     def test_power_on(self):
         # Ensure instance can be powered on.