Fix string comparisons (#1600)

azurelinuxagent/common/cgroup.py

@@ -32,10 +32,11 @@ def create(cgroup_path, controller, extension_name):
         """
         Factory method to create the correct CGroup.
         """
-        if controller is "cpu":
+        if controller == "cpu":
             return CpuCgroup(extension_name, cgroup_path)
-        elif controller is "memory":
+        if controller == "memory":
             return MemoryCgroup(extension_name, cgroup_path)
+        raise CGroupsException('CGroup controller {0} is not supported'.format(controller))
 
     def __init__(self, name, cgroup_path, controller_type):
         """

azurelinuxagent/common/cgroupstelemetry.py

@@ -19,6 +19,7 @@
 
 from azurelinuxagent.common import logger
 from azurelinuxagent.common.future import ustr
+from azurelinuxagent.common.exception import CGroupsException
 
 
 class CGroupsTelemetry(object):
@@ -165,10 +166,12 @@ def _add_cpu_usage(self, metric):
 
     def add_new_data(self, controller, metric):
         if metric:
-            if controller is "cpu":
+            if controller == "cpu":
                 self._add_cpu_usage(metric)
-            elif controller is "memory":
+            elif controller == "memory":
                 self._add_memory_usage(metric)
+            else:
+                raise CGroupsException('CGroup controller {0} is not supported'.format(controller))
 
     def get_metrics(self):
         return self._current_memory_usage, self._max_memory_levels, self._current_cpu_usage