Map libvirt error to InstanceNotFound in get_instance_disk_info

When getting instance disk info, the instance may be destroyed/deleted, and a
libvirtError will be raised in XMLDesc method, so catching and mapping it to
InstanceNotFound and the caller can handle it correctly.

Fixes bug #1064581

Change-Id: I07fed3e82e10dad4cb84ae5c8650ada351c24e78

2 files changed, 28 insertions, 1 deletions

diff --git a/nova/tests/test_libvirt.py b/nova/tests/test_libvirt.py
index cce220b20..ed7f2b509 100644
--- a/nova/tests/test_libvirt.py
+++ b/nova/tests/test_libvirt.py
@@ -4589,6 +4589,25 @@ class LibvirtDriverTestCase(test.TestCase):
         self.libvirtconnection._cleanup_resize(ins_ref,
                                             _fake_network_info(self.stubs, 1))
 
+    def test_get_instance_disk_info_exception(self):
+        instance_name = "fake-instance-name"
+
+        class FakeExceptionDomain(FakeVirtDomain):
+            def __init__(self):
+                super(FakeExceptionDomain, self).__init__()
+
+            def XMLDesc(self, *args):
+                raise libvirt.libvirtError("Libvirt error")
+
+        def fake_lookup_by_name(instance_name):
+            return FakeExceptionDomain()
+
+        self.stubs.Set(self.libvirtconnection, '_lookup_by_name',
+                       fake_lookup_by_name)
+        self.assertRaises(exception.InstanceNotFound,
+            self.libvirtconnection.get_instance_disk_info,
+            instance_name)
+
 
 class LibvirtVolumeUsageTestCase(test.TestCase):
     """Test for nova.virt.libvirt.libvirt_driver.LibvirtDriver
diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index 1f75c7ee2..32a7cc1ef 100644
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -2763,7 +2763,15 @@ class LibvirtDriver(driver.ComputeDriver):
         disk_info = []
 
         virt_dom = self._lookup_by_name(instance_name)
-        xml = virt_dom.XMLDesc(0)
+        try:
+            xml = virt_dom.XMLDesc(0)
+        except libvirt.libvirtError as ex:
+            error_code = ex.get_error_code()
+            msg = _("Error from libvirt while getting description of "
+                    "%(instance_name)s: [Error Code %(error_code)s] "
+                    "%(ex)s") % locals()
+            LOG.warn(msg)
+            raise exception.InstanceNotFound(instance_id=instance_name)
         doc = etree.fromstring(xml)
         disk_nodes = doc.findall('.//devices/disk')
         path_nodes = doc.findall('.//devices/disk/source')