Use taskflow library for building and executing action plans

The aim of this patchset is to integrate taskflow in
the Watcher Applier. Taskflow will help us a lot to make
Action Plan execution easy, consistent, scalable and reliable.

DocImpact

Partially implements: blueprint use-taskflow

Change-Id: I903d6509d74a61ad64e1506b8a7156e6e91abcfb
Closes-Bug: #1535326
Closes-Bug: #1531912

watcher/applier/actions/migration.py

@@ -0,0 +1,76 @@
+# -*- encoding: utf-8 -*-
+# Copyright (c) 2015 b<>com
+#
+# Authors: Jean-Emile DARTOIS <jean-emile.dartois@b-com.com>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+from oslo_log import log
+
+from watcher.applier.actions import base
+from watcher.common import exception
+from watcher.common import keystone as kclient
+from watcher.common import nova as nclient
+
+LOG = log.getLogger(__name__)
+
+
+class Migrate(base.BaseAction):
+    @property
+    def instance_uuid(self):
+        return self.applies_to
+
+    @property
+    def migration_type(self):
+        return self.input_parameters.get('migration_type')
+
+    @property
+    def dst_hypervisor(self):
+        return self.input_parameters.get('dst_hypervisor')
+
+    @property
+    def src_hypervisor(self):
+        return self.input_parameters.get('src_hypervisor')
+
+    def migrate(self, destination):
+        keystone = kclient.KeystoneClient()
+        wrapper = nclient.NovaClient(keystone.get_credentials(),
+                                     session=keystone.get_session())
+        LOG.debug("Migrate instance %s to %s  ", self.instance_uuid,
+                  destination)
+        instance = wrapper.find_instance(self.instance_uuid)
+        if instance:
+            if self.migration_type == 'live':
+                return wrapper.live_migrate_instance(
+                    instance_id=self.instance_uuid, dest_hostname=destination)
+            else:
+                raise exception.InvalidParameterValue(err=self.migration_type)
+        else:
+            raise exception.InstanceNotFound(name=self.instance_uuid)
+
+    def execute(self):
+        return self.migrate(destination=self.dst_hypervisor)
+
+    def revert(self):
+        return self.migrate(destination=self.src_hypervisor)
+
+    def precondition(self):
+        # todo(jed) check if the instance exist/ check if the instance is on
+        # the src_hypervisor
+        pass
+
+    def postcondition(self):
+        # todo(jed) we can image to check extra parameters (nework reponse,ect)
+        pass