Add doc for vm_workload_consolidation strategy

This patch adds documentation on requirements for
vm_workload_consolidation strategy.

Change-Id: I304644138b34658b09f7cd8f29eb089757807b61
Closes-bug: #1640820

doc/source/strategies/vm_workload_consolidation.rst

@@ -0,0 +1,100 @@
+==================================
+VM Workload Consolidation Strategy
+==================================
+
+Synopsis
+--------
+
+**display name**: ``vm_workload_consolidation``
+
+**goal**: ``vm_consolidation``
+
+    .. watcher-term:: watcher.decision_engine.strategy.strategies.vm_workload_consolidation
+
+Requirements
+------------
+
+Metrics
+*******
+
+The *vm_workload_consolidation* strategy requires the following metrics:
+
+============================ ============ ======= =======
+metric                       service name plugins comment
+============================ ============ ======= =======
+``memory``             	     ceilometer_  none
+``disk.root.size``           ceilometer_  none
+============================ ============ ======= =======
+
+The following metrics are not required but increase the accuracy of
+the strategy if available:
+
+============================ ============ ======= =======
+metric                       service name plugins comment
+============================ ============ ======= =======
+``memory.usage``             ceilometer_  none
+``cpu_util``                 ceilometer_  none
+============================ ============ ======= =======
+
+.. _ceilometer: http://docs.openstack.org/admin-guide/telemetry-measurements.html#openstack-compute
+
+Cluster data model
+******************
+
+Default Watcher's Compute cluster data model:
+
+    .. watcher-term:: watcher.decision_engine.model.collector.nova.NovaClusterDataModelCollector
+
+Actions
+*******
+
+Default Watcher's actions:
+
+
+    .. list-table::
+       :widths: 30 30
+       :header-rows: 1
+
+       * - action
+         - description
+       * - ``migration``
+         - .. watcher-term:: watcher.applier.actions.migration.Migrate
+       * - ``change_nova_service_state``
+         - .. watcher-term:: watcher.applier.actions.change_nova_service_state.ChangeNovaServiceState
+
+Planner
+*******
+
+Default Watcher's planner:
+
+    .. watcher-term:: watcher.decision_engine.planner.default.DefaultPlanner
+
+
+Efficacy Indicator
+------------------
+
+.. watcher-func::
+  :format: literal_block
+
+  watcher.decision_engine.goal.efficacy.specs.ServerConsolidation.get_global_efficacy_indicator
+
+Algorithm
+---------
+
+For more information on the VM Workload consolidation strategy please refer to: https://specs.openstack.org/openstack/watcher-specs/specs/mitaka/implemented/zhaw-load-consolidation.html
+
+How to use it ?
+---------------
+
+.. code-block:: shell
+
+    $ openstack optimize audittemplate create \
+      at1 vm_consolidation --strategy vm_workload_consolidation
+
+    $ openstack optimize audit create -a at1
+
+External Links
+--------------
+
+*Spec URL*
+https://specs.openstack.org/openstack/watcher-specs/specs/mitaka/implemented/zhaw-load-consolidation.html

watcher/decision_engine/strategy/strategies/vm_workload_consolidation.py

@@ -16,24 +16,9 @@
 # implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
-from oslo_log import log
-import six
-
-from watcher._i18n import _, _LE, _LI
-from watcher.common import exception
-from watcher.decision_engine.cluster.history import ceilometer \
-    as ceilometer_cluster_history
-from watcher.decision_engine.model import element
-from watcher.decision_engine.strategy.strategies import base
-
-LOG = log.getLogger(__name__)
-
-
-class VMWorkloadConsolidation(base.ServerConsolidationBaseStrategy):
-    """VM Workload Consolidation Strategy.
-
-    *Description*
+#
+"""
+*VM Workload Consolidation Strategy*
 
 A load consolidation strategy based on heuristic first-fit
 algorithm which focuses on measured CPU utilization and tries to
@@ -61,24 +46,28 @@ class VMWorkloadConsolidation(base.ServerConsolidationBaseStrategy):
 the cluster will appear more released (distributed) for the
 following consolidation phase.
 
-    As this strategy laverages VM live migration to move the load
+As this strategy leverages VM live migration to move the load
 from one compute node to another, this feature needs to be set up
 correctly on all compute nodes within the cluster.
 This strategy assumes it is possible to live migrate any VM from
 an active compute node to any other active compute node.
+"""
 
-    *Requirements*
+from oslo_log import log
+import six
 
-    * You must have at least 2 physical compute nodes to run this strategy.
+from watcher._i18n import _, _LE, _LI
+from watcher.common import exception
+from watcher.decision_engine.cluster.history import ceilometer \
+    as ceilometer_cluster_history
+from watcher.decision_engine.model import element
+from watcher.decision_engine.strategy.strategies import base
 
-    *Limitations*
+LOG = log.getLogger(__name__)
 
-    <None>
 
-    *Spec URL*
-
-    https://github.com/openstack/watcher-specs/blob/master/specs/mitaka/implemented/zhaw-load-consolidation.rst
-    """  # noqa
+class VMWorkloadConsolidation(base.ServerConsolidationBaseStrategy):
+    """VM Workload Consolidation Strategy"""
 
     def __init__(self, config, osc=None):
         super(VMWorkloadConsolidation, self).__init__(config, osc)