Enhance Watcher Applier Engine

Add a new config option 'action_execution_rule' which is a dict type.
Its key field is strategy name and the value is 'ALWAYS' or 'ANY'.
'ALWAYS' means the callback function returns True as usual.
'ANY' means the return depends on the result of previous action
execution. The callback returns True if previous action gets failed,
and the engine continues to run the next action. If previous action
executes success, the callback returns False then the next action
will be ignored.
For strategies that aren't in 'action_execution_rule', the callback
always returns True.

If exception is throwing out during the action execution, reverting will
be triggered by taskflow. To continue executing the next action,
we return False instead of throwing an exception.

Change-Id: Ib5afa214d8d097d739aad35d18b3fe5c8e4de8fc
Implements: blueprint enhance-watcher-applier-engine

watcher/applier/workflow_engine/base.py

@@ -58,6 +58,7 @@ class BaseWorkFlowEngine(loadable.Loadable):
         self._action_factory = factory.ActionFactory()
         self._osc = None
         self._is_notified = False
+        self.execution_rule = None
 
     @classmethod
     def get_config_opts(cls):
@@ -206,11 +207,14 @@ class BaseTaskFlowActionContainer(flow_task.Task):
         et = eventlet.spawn(_do_execute_action, *args, **kwargs)
         # NOTE: check for the state of action plan periodically,so that if
         # action is finished or action plan is cancelled we can exit from here.
+        result = False
         while True:
             action_object = objects.Action.get_by_uuid(
                 self.engine.context, self._db_action.uuid, eager=True)
             action_plan_object = objects.ActionPlan.get_by_id(
                 self.engine.context, action_object.action_plan_id)
+            if action_object.state == objects.action.State.SUCCEEDED:
+                result = True
             if (action_object.state in [objects.action.State.SUCCEEDED,
                objects.action.State.FAILED] or
                action_plan_object.state in CANCEL_STATE):
@@ -226,6 +230,7 @@ class BaseTaskFlowActionContainer(flow_task.Task):
             if (action_plan_object.state in CANCEL_STATE and abort):
                 et.kill()
             et.wait()
+            return result
 
             # NOTE: catch the greenlet exit exception due to thread kill,
             # taskflow will call revert for the action,
@@ -236,7 +241,8 @@ class BaseTaskFlowActionContainer(flow_task.Task):
 
         except Exception as e:
             LOG.exception(e)
-            raise
+            # return False instead of raising an exception
+            return False
 
     def post_execute(self):
         try: