Decorator for required variables

Added decorator to check that required class variables are present.

Change-Id: I6b90a7fccd4dca5675322ea2b9457c0fd0dcc658

os_faults/drivers/devstack.py

@@ -21,7 +21,7 @@ from os_faults.ansible import executor
 from os_faults.api import cloud_management
 from os_faults.api import node_collection
 from os_faults.api import service
-
+from os_faults import utils
 
 HostClass = namedtuple('HostClass', ['ip', 'mac'])
 
@@ -80,13 +80,15 @@ class DevStackService(service.Service):
     def get_nodes(self):
         return self.cloud_management.get_nodes()
 
+    @utils.require_variables('RESTART_CMD', 'SERVICE_NAME')
     def restart(self, nodes=None):
         task = {'command': self.RESTART_CMD}
         exec_res = self.cloud_management.execute(task)
-        logging.info('Restart the service, result: %s', exec_res)
+        logging.info('Restart %s result: %s', self.SERVICE_NAME, exec_res)
 
 
 class KeystoneService(DevStackService):
+    SERVICE_NAME = 'keystone'
     RESTART_CMD = 'service apache2 restart'
 
 

os_faults/drivers/fuel.py

@@ -24,6 +24,7 @@ from os_faults.api import cloud_management
 from os_faults.api import error
 from os_faults.api import node_collection
 from os_faults.api import service
+from os_faults import utils
 
 
 class FuelNodeCollection(node_collection.NodeCollection):
@@ -136,14 +137,14 @@ class FuelService(service.Service):
                                   power_management=self.power_management,
                                   hosts=hosts)
 
+    @utils.require_variables('RESTART_CMD', 'SERVICE_NAME')
     def restart(self, nodes=None):
-        if not getattr(self, 'RESTART_CMD'):
-            raise NotImplementedError('RESTART_CMD is undefined')
         nodes = nodes if nodes is not None else self.get_nodes()
         logging.info("Restart '%s' service on nodes: %s", self.SERVICE_NAME,
                      nodes.get_ips())
         self._run_task({'command': self.RESTART_CMD}, nodes)
 
+    @utils.require_variables('GREP', 'SERVICE_NAME')
     def kill(self, nodes=None):
         nodes = nodes if nodes is not None else self.get_nodes()
         logging.info("Kill '%s' service on nodes: %s", self.SERVICE_NAME,
@@ -151,6 +152,7 @@ class FuelService(service.Service):
         cmd = {'kill': {'grep': self.GREP, 'sig': signal.SIGKILL}}
         self._run_task(cmd, nodes)
 
+    @utils.require_variables('GREP', 'SERVICE_NAME')
     def freeze(self, nodes=None, sec=None):
         nodes = nodes if nodes is not None else self.get_nodes()
         if sec:
@@ -161,6 +163,7 @@ class FuelService(service.Service):
                      ('for %s sec ' % sec) if sec else '', nodes.get_ips())
         self._run_task(cmd, nodes)
 
+    @utils.require_variables('GREP', 'SERVICE_NAME')
     def unfreeze(self, nodes=None):
         nodes = nodes if nodes is not None else self.get_nodes()
         logging.info("Unfreeze '%s' service on nodes: %s", self.SERVICE_NAME,
@@ -168,6 +171,7 @@ class FuelService(service.Service):
         cmd = {'kill': {'grep': self.GREP, 'sig': signal.SIGCONT}}
         self._run_task(cmd, nodes)
 
+    @utils.require_variables('PORT', 'SERVICE_NAME')
     def plug(self, nodes=None):
         nodes = nodes if nodes is not None else self.get_nodes()
         logging.info("Open port %d for '%s' service on nodes: %s",
@@ -177,6 +181,7 @@ class FuelService(service.Service):
                                      'action': 'unblock',
                                      'service': self.SERVICE_NAME}}, nodes)
 
+    @utils.require_variables('PORT', 'SERVICE_NAME')
     def unplug(self, nodes=None):
         nodes = nodes if nodes is not None else self.get_nodes()
         logging.info("Close port %d for '%s' service on nodes: %s",

os_faults/tests/unit/test_utils.py

@@ -70,3 +70,29 @@ class UtilsTestCase(test.TestCase):
 
         thread_1.join.assert_called_once()
         thread_2.join.assert_called_once()
+
+
+class MyClass(object):
+    FOO = 10
+
+    @utils.require_variables('FOO')
+    def method(self, a, b):
+        return self.FOO + a + b
+
+    @utils.require_variables('BAR', 'BAZ')
+    def method_that_miss_variables(self):
+        return self.BAR, self.BAZ
+
+
+class RequiredVariablesTestCase(test.TestCase):
+
+    def test_require_variables(self):
+        inst = MyClass()
+        self.assertEqual(inst.method(1, b=2), 13)
+
+    def test_require_variables_not_implemented(self):
+        inst = MyClass()
+        err = self.assertRaises(NotImplementedError,
+                                inst.method_that_miss_variables)
+        msg = 'BAR, BAZ required for MyClass.method_that_miss_variables'
+        self.assertEqual(str(err), msg)

os_faults/utils.py

@@ -11,6 +11,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import functools
 import logging
 import threading
 import traceback
@@ -51,3 +52,22 @@ class ThreadsWrapper(object):
     def join_threads(self):
         for thread in self.threads:
             thread.join()
+
+
+def require_variables(*variables):
+    """Class method decorator to check that required variables are present"""
+    def decorator(fn):
+        @functools.wraps(fn)
+        def wrapper(self, *args, **kawrgs):
+            missing_vars = []
+            for var in variables:
+                if not hasattr(self, var):
+                    missing_vars.append(var)
+            if missing_vars:
+                missing_vars = ', '.join(missing_vars)
+                msg = '{} required for {}.{}'.format(
+                    missing_vars, self.__class__.__name__, fn.__name__)
+                raise NotImplementedError(msg)
+            return fn(self, *args, **kawrgs)
+        return wrapper
+    return decorator