Fixed bug 912701

Add an check to the list_instances method so that the domains whose ID
is 0 are not listed, since this is reserved in libvirt for hypervisors.

Refers to https://lists.launchpad.net/openstack/msg06699.html

Change-Id: I55f6f370cbaf8bd2254e08afad8b36d833726817

3 files changed, 17 insertions, 2 deletions

diff --git a/nova/tests/fakelibvirt.py b/nova/tests/fakelibvirt.py
index e47830e5c..309a6f10f 100644
--- a/nova/tests/fakelibvirt.py
+++ b/nova/tests/fakelibvirt.py
@@ -433,7 +433,7 @@ class Connection(object):
         self._uri = uri
         self._vms = {}
         self._running_vms = {}
-        self._id_counter = 0
+        self._id_counter = 1  # libvirt reserves 0 for the hypervisor.
         self._nwfilters = {}
 
     def _add_filter(self, nwfilter):
diff --git a/nova/tests/test_libvirt.py b/nova/tests/test_libvirt.py
index 1490f9173..894ac583e 100644
--- a/nova/tests/test_libvirt.py
+++ b/nova/tests/test_libvirt.py
@@ -91,6 +91,9 @@ class FakeVirtDomain(object):
                 </domain>
             """
 
+    def name(self):
+        return "fake-domain %s" % self
+
     def snapshotCreateXML(self, *args):
         return FakeVirDomainSnapshot(self)
 
@@ -401,6 +404,17 @@ class LibvirtConnTestCase(test.TestCase):
         self._check_xml_and_disk_bus({"disk_format": "iso"},
                                      "cdrom", "ide")
 
+    def test_list_instances(self):
+        self.mox.StubOutWithMock(connection.LibvirtConnection, '_conn')
+        connection.LibvirtConnection._conn.lookupByID = self.fake_lookup
+        connection.LibvirtConnection._conn.listDomainsID = lambda: [0, 1]
+
+        self.mox.ReplayAll()
+        conn = connection.LibvirtConnection(False)
+        instances = conn.list_instances()
+        # Only one should be listed, since domain with ID 0 must be skiped
+        self.assertEquals(len(instances), 1)
+
     @test.skip_if(missing_libvirt(), "Test requires libvirt")
     def test_snapshot_in_ami_format(self):
         self.flags(image_service='nova.image.fake.FakeImageService')
diff --git a/nova/virt/libvirt/connection.py b/nova/virt/libvirt/connection.py
index 4e5c86ea4..1a179b16b 100644
--- a/nova/virt/libvirt/connection.py
+++ b/nova/virt/libvirt/connection.py
@@ -268,7 +268,8 @@ class LibvirtConnection(driver.ComputeDriver):
 
     def list_instances(self):
         return [self._conn.lookupByID(x).name()
-                for x in self._conn.listDomainsID()]
+                for x in self._conn.listDomainsID()
+                if x != 0]  # We skip domains with ID 0 (hypervisors).
 
     @staticmethod
     def _map_to_instance_info(domain):