Create OpenStackClients convenience class

The OpenStackClients class provides a convenient way to create and
cache client instances.  The idea behind this code comes from Magnum
[0].

The OpenStackClients class will act as the manager of other project's
clients, providing an easy way to fetch instances of said clients. This
will allow the clients to be cached.

An instance of OpenStackClients is created for every call that comes
into the decision engine and the applier, using the request context to
pass needed (domain id) parameters to get a Keystone session.  This
instance should be shared as much as possible to avoid additional
unneccessary connections to the other services.

This class will also allow for the version of each client to be
configurable via the watcher.conf file.

The method by which a Keystone session is also changed to use the
keystoneauth1.loading library.  In order to avoid DuplicateOptErrors
with the keystone_authtoken group used for the keystonemiddleware in the
API code, a new conf group named "watcher_clients_auth" is created.  A
typical configuration using a password authentication scheme will look
like:
  [watcher_clients_auth]
  auth_type = password
  auth_url = http://<server-ip>:<port>
  username = <username>
  password = <password>
  project_domain_id = default
  user_domain_id = default

[0]: https://github.com/openstack/magnum/blob/master/magnum/common/clients.py

DocImpact
Change-Id: Iab9d0b304099686da2e9e2b19e8b1de4332ff378
Implements: blueprint external-api-versioning
Closes-Bug: #1530790
Closes-Bug: #1539670
Closes-Bug: #1522774

watcher/decision_engine/strategy/context/default.py

@@ -15,6 +15,7 @@
 # limitations under the License.
 from oslo_log import log
 
+from watcher.common import clients
 from watcher.decision_engine.strategy.context.base import BaseStrategyContext
 from watcher.decision_engine.strategy.selection.default import \
     DefaultStrategySelector
@@ -47,15 +48,17 @@ class DefaultStrategyContext(BaseStrategyContext):
         audit_template = objects.\
             AuditTemplate.get_by_id(request_context, audit.audit_template_id)
 
+        osc = clients.OpenStackClients()
+
         # todo(jed) retrieve in audit_template parameters (threshold,...)
         # todo(jed) create ActionPlan
-        collector_manager = self.collector.get_cluster_model_collector()
+        collector_manager = self.collector.get_cluster_model_collector(osc=osc)
 
         # todo(jed) remove call to get_latest_cluster_data_model
         cluster_data_model = collector_manager.get_latest_cluster_data_model()
 
-        selected_strategy = self.strategy_selector. \
-            define_from_goal(audit_template.goal)
+        selected_strategy = self.strategy_selector.define_from_goal(
+            audit_template.goal, osc=osc)
 
         # todo(jed) add parameters and remove cluster_data_model
         return selected_strategy.execute(cluster_data_model)

watcher/decision_engine/strategy/selection/default.py

@@ -48,11 +48,12 @@ class DefaultStrategySelector(base.BaseSelector):
         super(DefaultStrategySelector, self).__init__()
         self.strategy_loader = default.DefaultStrategyLoader()
 
-    def define_from_goal(self, goal_name):
+    def define_from_goal(self, goal_name, osc=None):
+        """:param osc: an OpenStackClients instance"""
         strategy_to_load = None
         try:
             strategy_to_load = CONF.watcher_goals.goals[goal_name]
-            return self.strategy_loader.load(strategy_to_load)
+            return self.strategy_loader.load(strategy_to_load, osc=osc)
         except KeyError as exc:
             LOG.exception(exc)
             raise exception.WatcherException(

watcher/decision_engine/strategy/strategies/base.py

@@ -33,10 +33,11 @@ provided as well.
 """
 
 import abc
+
 from oslo_log import log
 import six
 
-
+from watcher.common import clients
 from watcher.decision_engine.solution.default import DefaultSolution
 from watcher.decision_engine.strategy.common.level import StrategyLevel
 
@@ -51,7 +52,8 @@ class BaseStrategy(object):
     Solution for a given Goal.
     """
 
-    def __init__(self, name=None, description=None):
+    def __init__(self, name=None, description=None, osc=None):
+        """:param osc: an OpenStackClients instance"""
         self._name = name
         self.description = description
         # default strategy level
@@ -59,6 +61,7 @@ class BaseStrategy(object):
         self._cluster_state_collector = None
         # the solution given by the strategy
         self._solution = DefaultSolution()
+        self._osc = osc
 
     @abc.abstractmethod
     def execute(self, model):
@@ -70,6 +73,12 @@ class BaseStrategy(object):
         :rtype: :class:`watcher.decision_engine.solution.base.BaseSolution`
         """
 
+    @property
+    def osc(self):
+        if not self._osc:
+            self._osc = clients.OpenStackClients()
+        return self._osc
+
     @property
     def solution(self):
         return self._solution

watcher/decision_engine/strategy/strategies/basic_consolidation.py

@@ -41,7 +41,8 @@ class BasicConsolidation(BaseStrategy):
     MIGRATION = "migrate"
     CHANGE_NOVA_SERVICE_STATE = "change_nova_service_state"
 
-    def __init__(self, name=DEFAULT_NAME, description=DEFAULT_DESCRIPTION):
+    def __init__(self, name=DEFAULT_NAME, description=DEFAULT_DESCRIPTION,
+                 osc=None):
         """Basic offline Consolidation using live migration
 
     The basic consolidation algorithm has several limitations.
@@ -68,8 +69,9 @@ class BasicConsolidation(BaseStrategy):
 
         :param name: the name of the strategy
         :param description: a description of the strategy
+        :param osc: an OpenStackClients object
         """
-        super(BasicConsolidation, self).__init__(name, description)
+        super(BasicConsolidation, self).__init__(name, description, osc)
 
         # set default value for the number of released nodes
         self.number_of_released_nodes = 0
@@ -102,7 +104,7 @@ class BasicConsolidation(BaseStrategy):
     @property
     def ceilometer(self):
         if self._ceilometer is None:
-            self._ceilometer = CeilometerClusterHistory()
+            self._ceilometer = CeilometerClusterHistory(osc=self.osc)
         return self._ceilometer
 
     @ceilometer.setter

watcher/decision_engine/strategy/strategies/dummy_strategy.py

@@ -30,8 +30,9 @@ class DummyStrategy(BaseStrategy):
     NOP = "nop"
     SLEEP = "sleep"
 
-    def __init__(self, name=DEFAULT_NAME, description=DEFAULT_DESCRIPTION):
-        super(DummyStrategy, self).__init__(name, description)
+    def __init__(self, name=DEFAULT_NAME, description=DEFAULT_DESCRIPTION,
+                 osc=None):
+        super(DummyStrategy, self).__init__(name, description, osc)
 
     def execute(self, model):
         parameters = {'message': 'hello World'}

watcher/decision_engine/strategy/strategies/outlet_temp_control.py

@@ -40,7 +40,8 @@ class OutletTempControl(BaseStrategy):
 
     MIGRATION = "migrate"
 
-    def __init__(self, name=DEFAULT_NAME, description=DEFAULT_DESCRIPTION):
+    def __init__(self, name=DEFAULT_NAME, description=DEFAULT_DESCRIPTION,
+                 osc=None):
         """[PoC]Outlet temperature control using live migration
 
         It is a migration strategy based on the Outlet Temperature of physical
@@ -67,8 +68,9 @@ class OutletTempControl(BaseStrategy):
 
         :param name: the name of the strategy
         :param description: a description of the strategy
+        :param osc: an OpenStackClients object
         """
-        super(OutletTempControl, self).__init__(name, description)
+        super(OutletTempControl, self).__init__(name, description, osc)
         # the migration plan will be triggered when the outlet temperature
         # reaches threshold
         # TODO(zhenzanz): Threshold should be configurable for each audit
@@ -79,7 +81,7 @@ class OutletTempControl(BaseStrategy):
     @property
     def ceilometer(self):
         if self._ceilometer is None:
-            self._ceilometer = CeilometerClusterHistory()
+            self._ceilometer = CeilometerClusterHistory(osc=self.osc)
         return self._ceilometer
 
     @ceilometer.setter