Raise exceptions when Spice/VNC are unavailable

Bug 1192724

Both Spice and/or VNC may be enabled from the perspective of compute
configuration but their actual availability can vary based on
whether either was enabled/disabled at the time the instance was
launched. This patch raises a proper exception in this case, such
that clients (including Horizon) can either message the user or fall
back.

Change-Id: If06e726e606f4a27c8ec4617400b728ce7112e3b

nova/exception.py

@@ -839,6 +839,10 @@ class ConsoleTypeInvalid(Invalid):
     msg_fmt = _("Invalid console type %(console_type)s")
 
 
+class ConsoleTypeUnavailable(Invalid):
+    message = _("Unavailable console type %(console_type)s")
+
+
 class InstanceTypeNotFound(NotFound):
     msg_fmt = _("Instance type %(instance_type_id)s could not be found.")
 

nova/tests/virt/libvirt/test_libvirt.py

@@ -4204,6 +4204,86 @@ class LibvirtConnTestCase(test.TestCase):
                           power_on=False)
         self.assertTrue(self.log_error_called)
 
+    def test_get_vnc_console(self):
+        instance_ref = db.instance_create(self.context, self.test_instance)
+        dummyxml = ("<domain type='kvm'><name>instance-0000000a</name>"
+                    "<devices>"
+                    "<graphics type='vnc' port='5900'/>"
+                    "</devices></domain>")
+
+        vdmock = self.mox.CreateMock(libvirt.virDomain)
+        self.mox.StubOutWithMock(vdmock, "XMLDesc")
+        vdmock.XMLDesc(0).AndReturn(dummyxml)
+
+        def fake_lookup(instance_name):
+            if instance_name == instance_ref['name']:
+                return vdmock
+        self.create_fake_libvirt_mock(lookupByName=fake_lookup)
+
+        self.mox.ReplayAll()
+        conn = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
+        vnc_dict = conn.get_vnc_console(instance_ref)
+        self.assertEquals(vnc_dict['port'], '5900')
+
+    def test_get_vnc_console_unavailable(self):
+        instance_ref = db.instance_create(self.context, self.test_instance)
+        dummyxml = ("<domain type='kvm'><name>instance-0000000a</name>"
+                    "<devices></devices></domain>")
+
+        vdmock = self.mox.CreateMock(libvirt.virDomain)
+        self.mox.StubOutWithMock(vdmock, "XMLDesc")
+        vdmock.XMLDesc(0).AndReturn(dummyxml)
+
+        def fake_lookup(instance_name):
+            if instance_name == instance_ref['name']:
+                return vdmock
+        self.create_fake_libvirt_mock(lookupByName=fake_lookup)
+
+        self.mox.ReplayAll()
+        conn = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
+        self.assertRaises(exception.ConsoleTypeUnavailable,
+                          conn.get_vnc_console, instance_ref)
+
+    def test_get_spice_console(self):
+        instance_ref = db.instance_create(self.context, self.test_instance)
+        dummyxml = ("<domain type='kvm'><name>instance-0000000a</name>"
+                    "<devices>"
+                    "<graphics type='spice' port='5950'/>"
+                    "</devices></domain>")
+
+        vdmock = self.mox.CreateMock(libvirt.virDomain)
+        self.mox.StubOutWithMock(vdmock, "XMLDesc")
+        vdmock.XMLDesc(0).AndReturn(dummyxml)
+
+        def fake_lookup(instance_name):
+            if instance_name == instance_ref['name']:
+                return vdmock
+        self.create_fake_libvirt_mock(lookupByName=fake_lookup)
+
+        self.mox.ReplayAll()
+        conn = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
+        spice_dict = conn.get_spice_console(instance_ref)
+        self.assertEquals(spice_dict['port'], '5950')
+
+    def test_get_spice_console_unavailable(self):
+        instance_ref = db.instance_create(self.context, self.test_instance)
+        dummyxml = ("<domain type='kvm'><name>instance-0000000a</name>"
+                    "<devices></devices></domain>")
+
+        vdmock = self.mox.CreateMock(libvirt.virDomain)
+        self.mox.StubOutWithMock(vdmock, "XMLDesc")
+        vdmock.XMLDesc(0).AndReturn(dummyxml)
+
+        def fake_lookup(instance_name):
+            if instance_name == instance_ref['name']:
+                return vdmock
+        self.create_fake_libvirt_mock(lookupByName=fake_lookup)
+
+        self.mox.ReplayAll()
+        conn = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
+        self.assertRaises(exception.ConsoleTypeUnavailable,
+                          conn.get_spice_console, instance_ref)
+
 
 class HostStateTestCase(test.TestCase):
 

nova/virt/libvirt/driver.py

@@ -1701,6 +1701,9 @@ class LibvirtDriver(driver.ComputeDriver):
             for graphic in dom.getElementsByTagName('graphics'):
                 if graphic.getAttribute('type') == 'vnc':
                     return graphic.getAttribute('port')
+            # NOTE(rmk): We had VNC consoles enabled but the instance in
+            # question is not actually listening for connections.
+            raise exception.ConsoleTypeUnavailable(console_type='vnc')
 
         port = get_vnc_port_for_instance(instance['name'])
         host = CONF.vncserver_proxyclient_address
@@ -1719,8 +1722,9 @@ class LibvirtDriver(driver.ComputeDriver):
                 if graphic.getAttribute('type') == 'spice':
                     return (graphic.getAttribute('port'),
                             graphic.getAttribute('tlsPort'))
-
-            return (None, None)
+            # NOTE(rmk): We had Spice consoles enabled but the instance in
+            # question is not actually listening for connections.
+            raise exception.ConsoleTypeUnavailable(console_type='spice')
 
         ports = get_spice_ports_for_instance(instance['name'])
         host = CONF.spice.server_proxyclient_address