Cancel Action Plan

This patch adds feature to cancel action plan in watcher.
A General flow from watcher-api to watcher-applier is implemented.

action plan cancel can cancel any [ongoing, pending, recommended]
action plan, it will update the action states also to "cancelled".
For ongoing actions in action plan, actions needs to be aborted.
Seperate patches will be added to support abort operation
in each action.

Notification part is addressed by a seperate blueprint.
https://blueprints.launchpad.net/watcher/+spec/notifications-actionplan-cancel

Change-Id: I895a5eaca5239d5657702c8d1875b9ece21682dc
Partially-Implements: blueprint cancel-action-plan

watcher/applier/actions/base.py

@@ -32,6 +32,9 @@ class BaseAction(loadable.Loadable):
     # watcher dashboard and will be nested in input_parameters
     RESOURCE_ID = 'resource_id'
 
+    # Add action class name to the list, if implementing abort.
+    ABORT_TRUE = ['Sleep', 'Nop']
+
     def __init__(self, config, osc=None):
         """Constructor
 
@@ -134,3 +137,6 @@ class BaseAction(loadable.Loadable):
     def get_description(self):
         """Description of the action"""
         raise NotImplementedError()
+
+    def check_abort(self):
+        return bool(self.__class__.__name__ in self.ABORT_TRUE)

watcher/applier/actions/migration.py

@@ -164,6 +164,10 @@ class Migrate(base.BaseAction):
     def revert(self):
         return self.migrate(destination=self.source_node)
 
+    def abort(self):
+        # TODO(adisky): implement abort for migration
+        LOG.warning("Abort for migration not implemented")
+
     def pre_condition(self):
         # TODO(jed): check if the instance exists / check if the instance is on
         # the source_node

watcher/applier/actions/nop.py

@@ -23,7 +23,6 @@ import voluptuous
 
 from watcher.applier.actions import base
 
-
 LOG = log.getLogger(__name__)
 
 
@@ -69,3 +68,6 @@ class Nop(base.BaseAction):
     def get_description(self):
         """Description of the action"""
         return "Logging a NOP message"
+
+    def abort(self):
+        LOG.debug("Abort action NOP")

watcher/applier/actions/sleep.py

@@ -70,3 +70,6 @@ class Sleep(base.BaseAction):
     def get_description(self):
         """Description of the action"""
         return "Wait for a given interval in seconds."
+
+    def abort(self):
+        LOG.debug("Abort action sleep")