Add hypervisor inspector sanity check

Based on existed self-disabled pollster, this sanity check would
prevent pollsters on mis-configured inspector from being loaded.

Change-Id: Ic4a7ce010e17b2f0f356687cc61a59276d59283d
Closes-Bug: #1485560

ceilometer/compute/pollsters/__init__.py

@@ -24,6 +24,11 @@ from ceilometer.compute.virt import inspector as virt_inspector
 @six.add_metaclass(abc.ABCMeta)
 class BaseComputePollster(plugin_base.PollsterBase):
 
+    def setup_environment(self):
+        super(BaseComputePollster, self).setup_environment()
+        # propagate exception from check_sanity
+        self.inspector.check_sanity()
+
     @property
     def inspector(self):
         try:

ceilometer/compute/virt/inspector.py

@@ -184,10 +184,22 @@ class NoDataException(InspectorException):
     pass
 
 
+class NoSanityException(InspectorException):
+    pass
+
+
 # Main virt inspector abstraction layering over the hypervisor API.
 #
 class Inspector(object):
 
+    def check_sanity(self):
+        """Check the sanity of hypervisor inspector.
+
+        Each subclass could overwrite it to throw any exception
+        when detecting mis-configured inspector
+        """
+        pass
+
     def inspect_cpus(self, instance):
         """Inspect the CPU statistics for an instance.
 

ceilometer/compute/virt/libvirt/inspector.py

@@ -81,6 +81,10 @@ class LibvirtInspector(virt_inspector.Inspector):
 
         return self.connection
 
+    def check_sanity(self):
+        if not self._get_connection():
+            raise virt_inspector.NoSanityException()
+
     @retry_on_disconnect
     def _lookup_by_uuid(self, instance):
         instance_name = util.instance_name(instance)

ceilometer/tests/unit/agent/test_manager.py

@@ -39,6 +39,9 @@ class PollingException(Exception):
     pass
 
 
+@mock.patch('ceilometer.compute.pollsters.'
+            'BaseComputePollster.setup_environment',
+            mock.Mock(return_value=None))
 class TestManager(base.BaseTestCase):
 
     @mock.patch('ceilometer.pipeline.setup_polling', mock.MagicMock())
@@ -181,6 +184,9 @@ class TestRunTasks(agentbase.BaseAgentManagerTestCase):
             resource_metadata=agentbase.default_test_data.resource_metadata)
 
     @staticmethod
+    @mock.patch('ceilometer.compute.pollsters.'
+                'BaseComputePollster.setup_environment',
+                mock.Mock(return_value=None))
     def create_manager():
         return manager.AgentManager()
 

ceilometer/tests/unit/compute/virt/libvirt/test_inspector.py

@@ -341,3 +341,25 @@ class TestLibvirtInspectionWithError(base.BaseTestCase):
     def test_inspect_unknown_error(self):
         self.assertRaises(virt_inspector.InspectorException,
                           self.inspector.inspect_cpus, 'foo')
+
+
+class TestLibvirtInitWithError(base.BaseTestCase):
+
+    def setUp(self):
+        super(TestLibvirtInitWithError, self).setUp()
+        self.inspector = libvirt_inspector.LibvirtInspector()
+        libvirt_inspector.libvirt = mock.Mock()
+
+    @mock.patch('ceilometer.compute.virt.libvirt.inspector.'
+                'LibvirtInspector._get_connection',
+                mock.Mock(return_value=None))
+    def test_init_error(self):
+        self.assertRaises(virt_inspector.NoSanityException,
+                          self.inspector.check_sanity)
+
+    @mock.patch('ceilometer.compute.virt.libvirt.inspector.'
+                'LibvirtInspector._get_connection',
+                mock.Mock(side_effect=virt_inspector.NoDataException))
+    def test_init_exception(self):
+        self.assertRaises(virt_inspector.NoDataException,
+                          self.inspector.check_sanity)