Merge "Optimize NovaHelper.get_compute_node_by_hostname"

watcher/common/nova_helper.py

@@ -61,23 +61,23 @@ class NovaHelper(object):
                                             detailed=detailed)
 
     def get_compute_node_by_hostname(self, node_hostname):
-        """Get compute node by hostname"""
-        # TODO(mriedem): This method could be optimized if
-        # GET /os-hypervisors/detail had a host filter parameter.
-        try:
-            hypervisors = [hv for hv in self.get_compute_node_list()
-                           if hv.service['host'] == node_hostname]
-            if len(hypervisors) != 1:
-                # TODO(hidekazu)
-                # this may occur if ironic driver is used
-                raise exception.ComputeNodeNotFound(name=node_hostname)
-            else:
-                compute_nodes = self.get_compute_node_by_name(
-                    hypervisors[0].hypervisor_hostname, detailed=True)
-                if len(compute_nodes) != 1:
-                    raise exception.ComputeNodeNotFound(name=node_hostname)
+        """Get compute node by hostname
 
-                return compute_nodes[0]
+        :param node_hostname: Compute service hostname
+        :returns: novaclient.v2.hypervisors.Hypervisor object if found
+        :raises: ComputeNodeNotFound if no hypervisor is found for the compute
+            service hostname or there was an error communicating with nova
+        """
+        try:
+            # This is a fuzzy match on hypervisor_hostname so we could get back
+            # more than one compute node. If so, match on the compute service
+            # hostname.
+            compute_nodes = self.get_compute_node_by_name(
+                node_hostname, detailed=True)
+            for cn in compute_nodes:
+                if cn.service['host'] == node_hostname:
+                    return cn
+            raise exception.ComputeNodeNotFound(name=node_hostname)
         except Exception as exc:
             LOG.exception(exc)
             raise exception.ComputeNodeNotFound(name=node_hostname)

watcher/tests/common/test_nova_helper.py

@@ -121,9 +121,6 @@ class TestNovaHelper(base.TestCase):
         hypervisor_id = utils.generate_uuid()
         hypervisor_name = "fake_hypervisor_1"
         hypervisor = self.fake_hypervisor(hypervisor_id, hypervisor_name)
-        self.fake_nova_hypervisor_list(
-            nova_util,
-            fake_list=[hypervisor])
         nova_util.nova.hypervisors.search.return_value = [hypervisor]
         # verify that the compute node can be obtained normally by name
         self.assertEqual(
@@ -145,6 +142,25 @@ class TestNovaHelper(base.TestCase):
             nova_util.get_compute_node_by_hostname,
             hypervisor_name)
 
+    def test_get_compute_node_by_hostname_multiple_matches(self, *mocks):
+        # Tests a scenario where get_compute_node_by_name returns multiple
+        # hypervisors and we have to pick the exact match based on the given
+        # compute service hostname.
+        nova_util = nova_helper.NovaHelper()
+        nodes = []
+        # compute1 is a substring of compute10 to trigger the fuzzy match.
+        for hostname in ('compute1', 'compute10'):
+            node = mock.MagicMock()
+            node.id = utils.generate_uuid()
+            node.hypervisor_hostname = hostname
+            node.service = {'host': hostname}
+            nodes.append(node)
+        # We should get back exact matches based on the service host.
+        nova_util.nova.hypervisors.search.return_value = nodes
+        for index, name in enumerate(['compute1', 'compute10']):
+            result = nova_util.get_compute_node_by_hostname(name)
+            self.assertIs(nodes[index], result)
+
     def test_get_instance_list(self, *args):
         nova_util = nova_helper.NovaHelper()
         # Call it once with no filters.