Prevent the migration of VM with 'optimize' False in VM metadata

This patch adds the functionality to filter out VMs which have metadata field 'optimize' set to False. This patch implements the functionality for basic_consolidation strategy. Change-Id: Iaf7b63e09534e4a67406e7f092242558b78c0bde Partially-Implements: BP audit-tag-vm-metadata
2017-03-27 08:05:18 +00:00
parent a644600a18
commit a2cb02a861
17 changed files with 131 additions and 91 deletions
--- a/watcher/decision_engine/model/element/instance.py
+++ b/watcher/decision_engine/model/element/instance.py
@@ -48,7 +48,7 @@ class Instance(compute_resource.ComputeResource):
        "disk": wfields.IntegerField(),
        "disk_capacity": wfields.NonNegativeIntegerField(),
        "vcpus": wfields.NonNegativeIntegerField(),
-        "metadata": wfields.DictField(),
+        "metadata": wfields.JsonField(),
    }

    def accept(self, visitor):
--- a/watcher/decision_engine/model/model_root.py
+++ b/watcher/decision_engine/model/model_root.py
@@ -235,3 +235,10 @@ class ModelRoot(nx.DiGraph, base.Model):
                model.add_instance(instance)

        return model
+
+    @classmethod
+    def is_isomorphic(cls, G1, G2):
+        def node_match(node1, node2):
+            return node1.as_dict() == node2.as_dict()
+        return nx.algorithms.isomorphism.isomorph.is_isomorphic(
+            G1, G2, node_match=node_match)
--- a/watcher/decision_engine/strategy/strategies/base.py
+++ b/watcher/decision_engine/strategy/strategies/base.py
@@ -39,6 +39,8 @@ which are dynamically loaded by Watcher at launch time.
 import abc
 import six

+from oslo_utils import strutils
+
 from watcher.common import clients
 from watcher.common import context
 from watcher.common import exception
@@ -264,6 +266,22 @@ class BaseStrategy(loadable.Loadable):
    def state_collector(self, s):
        self._cluster_state_collector = s

+    def filter_instances_by_audit_tag(self, instances):
+        if not self.config.check_optimize_metadata:
+            return instances
+        instances_to_migrate = []
+        for instance in instances:
+            optimize = True
+            if instance.metadata:
+                try:
+                    optimize = strutils.bool_from_string(
+                        instance.metadata.get('optimize'))
+                except ValueError:
+                    optimize = False
+            if optimize:
+                instances_to_migrate.append(instance)
+        return instances_to_migrate
+

@six.add_metaclass(abc.ABCMeta)
 class DummyBaseStrategy(BaseStrategy):
--- a/watcher/decision_engine/strategy/strategies/basic_consolidation.py
+++ b/watcher/decision_engine/strategy/strategies/basic_consolidation.py
@@ -159,7 +159,12 @@ class BasicConsolidation(base.ServerConsolidationBaseStrategy):
                "datasource",
                help="Data source to use in order to query the needed metrics",
                default="ceilometer",
-                choices=["ceilometer", "monasca", "gnocchi"])
+                choices=["ceilometer", "monasca", "gnocchi"]),
+            cfg.BoolOpt(
+                "check_optimize_metadata",
+                help="Check optimize metadata field in instance before "
+                     "migration",
+                default=False),
        ]

    @property
@@ -437,9 +442,10 @@ class BasicConsolidation(base.ServerConsolidationBaseStrategy):
    def node_and_instance_score(self, sorted_scores):
        """Get List of VMs from node"""
        node_to_release = sorted_scores[len(sorted_scores) - 1][0]
-        instances_to_migrate = self.compute_model.get_node_instances(
+        instances = self.compute_model.get_node_instances(
            self.compute_model.get_node_by_uuid(node_to_release))

+        instances_to_migrate = self.filter_instances_by_audit_tag(instances)
        instance_score = []
        for instance in instances_to_migrate:
            if instance.state == element.InstanceState.ACTIVE.value:
--- a/watcher/objects/fields.py
+++ b/watcher/objects/fields.py
@@ -17,6 +17,7 @@
 import ast
 import six

+from oslo_serialization import jsonutils
 from oslo_versionedobjects import fields


@@ -96,8 +97,26 @@ class FlexibleListOfDictField(fields.AutoTypedField):
        super(FlexibleListOfDictField, self)._null(obj, attr)


+class Json(fields.FieldType):
+    def coerce(self, obj, attr, value):
+        if isinstance(value, six.string_types):
+            loaded = jsonutils.loads(value)
+            return loaded
+        return value
+
+    def from_primitive(self, obj, attr, value):
+        return self.coerce(obj, attr, value)
+
+    def to_primitive(self, obj, attr, value):
+        return jsonutils.dumps(value)
+
+
+class JsonField(fields.AutoTypedField):
+    AUTO_TYPE = Json()
+
 # ### Notification fields ### #

+
 class BaseWatcherEnum(Enum):

    ALL = ()
--- a/watcher/tests/decision_engine/model/data/scenario_1.xml
+++ b/watcher/tests/decision_engine/model/data/scenario_1.xml
@@ -1,47 +1,47 @@
 <ModelRoot>
  <ComputeNode human_id="" uuid="Node_0" status="enabled" state="up" id="0" hostname="hostname_0" vcpus="40" disk="250" disk_capacity="250" memory="132">
-    <Instance state="active" human_id="" uuid="INSTANCE_0" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-    <Instance state="active" human_id="" uuid="INSTANCE_1" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
+    <Instance state="active" human_id="" uuid="INSTANCE_0" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+    <Instance state="active" human_id="" uuid="INSTANCE_1" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
  <ComputeNode human_id="" uuid="Node_1" status="enabled" state="up" id="1" hostname="hostname_1" vcpus="40" disk="250" disk_capacity="250" memory="132">
-    <Instance state="active" human_id="" uuid="INSTANCE_2" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
+    <Instance state="active" human_id="" uuid="INSTANCE_2" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
  <ComputeNode human_id="" uuid="Node_2" status="enabled" state="up" id="2" hostname="hostname_2" vcpus="40" disk="250" disk_capacity="250" memory="132">
-    <Instance state="active" human_id="" uuid="INSTANCE_3" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-    <Instance state="active" human_id="" uuid="INSTANCE_4" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-    <Instance state="active" human_id="" uuid="INSTANCE_5" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
+    <Instance state="active" human_id="" uuid="INSTANCE_3" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+    <Instance state="active" human_id="" uuid="INSTANCE_4" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+    <Instance state="active" human_id="" uuid="INSTANCE_5" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
  <ComputeNode human_id="" uuid="Node_3" status="enabled" state="up" id="3" hostname="hostname_3" vcpus="40" disk="250" disk_capacity="250" memory="132">
-    <Instance state="active" human_id="" uuid="INSTANCE_6" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
+    <Instance state="active" human_id="" uuid="INSTANCE_6" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
  <ComputeNode human_id="" uuid="Node_4" status="enabled" state="up" id="4" hostname="hostname_4" vcpus="40" disk="250" disk_capacity="250" memory="132">
-    <Instance state="active" human_id="" uuid="INSTANCE_7" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
+    <Instance state="active" human_id="" uuid="INSTANCE_7" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
-  <Instance state="active" human_id="" uuid="INSTANCE_10" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_11" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_12" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_13" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_14" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_15" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_16" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_17" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_18" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_19" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_20" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_21" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_22" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_23" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_24" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_25" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_26" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_27" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_28" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_29" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_30" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_31" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_32" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_33" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_34" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_8" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-  <Instance state="active" human_id="" uuid="INSTANCE_9" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
+  <Instance state="active" human_id="" uuid="INSTANCE_10" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_11" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_12" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_13" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_14" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_15" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_16" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_17" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_18" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_19" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_20" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_21" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_22" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_23" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_24" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_25" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_26" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_27" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_28" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_29" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_30" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_31" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_32" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_33" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_34" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_8" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+  <Instance state="active" human_id="" uuid="INSTANCE_9" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
 </ModelRoot>
--- a/watcher/tests/decision_engine/model/data/scenario_1_with_metrics.xml
+++ b/watcher/tests/decision_engine/model/data/scenario_1_with_metrics.xml
@@ -1,8 +1,8 @@
 <ModelRoot>
  <ComputeNode hostname="hostname_0" uuid="Node_0" id="0" state="enabled" human_id="" status="enabled" vcpus="40" disk="250" disk_capacity="250" memory="64">
-    <Instance human_id="" state="active" uuid="INSTANCE_0" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
+    <Instance human_id="" state="active" uuid="INSTANCE_0" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
  <ComputeNode hostname="hostname_1" uuid="Node_1" id="1" state="enabled" human_id="" status="enabled" vcpus="40" disk="250" disk_capacity="250" memory="64">
-    <Instance human_id="" state="active" uuid="INSTANCE_1" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
+    <Instance human_id="" state="active" uuid="INSTANCE_1" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
 </ModelRoot>
--- a/watcher/tests/decision_engine/model/data/scenario_2_with_metrics.xml
+++ b/watcher/tests/decision_engine/model/data/scenario_2_with_metrics.xml
@@ -1,11 +1,11 @@
 <ModelRoot>
  <ComputeNode hostname="hostname_0" uuid="Node_0" id="0" state="up" human_id="" status="enabled" vcpus="16" disk="250" disk_capacity="250" memory="64">
-    <Instance human_id="" state="active" uuid="INSTANCE_0" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-    <Instance human_id="" state="active" uuid="INSTANCE_1" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-    <Instance human_id="" state="active" uuid="INSTANCE_2" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-    <Instance human_id="" state="active" uuid="INSTANCE_3" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-    <Instance human_id="" state="active" uuid="INSTANCE_4" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-    <Instance human_id="" state="active" uuid="INSTANCE_5" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
+    <Instance human_id="" state="active" uuid="INSTANCE_0" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+    <Instance human_id="" state="active" uuid="INSTANCE_1" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+    <Instance human_id="" state="active" uuid="INSTANCE_2" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+    <Instance human_id="" state="active" uuid="INSTANCE_3" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+    <Instance human_id="" state="active" uuid="INSTANCE_4" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+    <Instance human_id="" state="active" uuid="INSTANCE_5" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
  <ComputeNode hostname="hostname_1" uuid="Node_1" id="1" state="up" human_id="" status="enabled" vcpus="16" disk="250" disk_capacity="250" memory="64"/>
  <ComputeNode hostname="hostname_2" uuid="Node_2" id="2" state="up" human_id="" status="enabled" vcpus="16" disk="250" disk_capacity="250" memory="64"/>
--- a/watcher/tests/decision_engine/model/data/scenario_3_with_2_nodes.xml
+++ b/watcher/tests/decision_engine/model/data/scenario_3_with_2_nodes.xml
@@ -1,8 +1,8 @@
 <ModelRoot>
  <ComputeNode human_id="" uuid="Node_0" status="enabled" state="up" id="0" hostname="hostname_0" vcpus="40" disk="250" disk_capacity="250" memory="132">
-    <Instance state="active" human_id="" uuid="73b09e16-35b7-4922-804e-e8f5d9b740fc" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
+    <Instance state="active" human_id="" uuid="73b09e16-35b7-4922-804e-e8f5d9b740fc" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
  <ComputeNode human_id="" uuid="Node_1" status="enabled" state="up" id="1" hostname="hostname_1" vcpus="40" disk="250" disk_capacity="250" memory="132">
-    <Instance state="active" human_id="" uuid="a4cab39b-9828-413a-bf88-f76921bf1517" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
+    <Instance state="active" human_id="" uuid="a4cab39b-9828-413a-bf88-f76921bf1517" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
 </ModelRoot>
--- a/watcher/tests/decision_engine/model/data/scenario_3_with_metrics.xml
+++ b/watcher/tests/decision_engine/model/data/scenario_3_with_metrics.xml
@@ -1,9 +1,9 @@
 <ModelRoot>
  <ComputeNode hostname="hostname_0" uuid="Node_0" id="0" state="up" human_id="" status="enabled" vcpus="10" disk="250" disk_capacity="250" memory="64">
-    <Instance human_id="" state="active" uuid="INSTANCE_6" vcpus="1" disk="20" disk_capacity="20" memory="2"/>
-    <Instance human_id="" state="active" uuid="INSTANCE_7" vcpus="2" disk="20" disk_capacity="20" memory="2"/>
-    <Instance human_id="" state="active" uuid="INSTANCE_8" vcpus="4" disk="20" disk_capacity="20" memory="2"/>
-    <Instance human_id="" state="active" uuid="INSTANCE_9" vcpus="8" disk="20" disk_capacity="20" memory="2"/>
+    <Instance human_id="" state="active" uuid="INSTANCE_6" vcpus="1" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+    <Instance human_id="" state="active" uuid="INSTANCE_7" vcpus="2" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+    <Instance human_id="" state="active" uuid="INSTANCE_8" vcpus="4" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+    <Instance human_id="" state="active" uuid="INSTANCE_9" vcpus="8" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
  <ComputeNode hostname="hostname_1" uuid="Node_1" id="1" state="up" human_id="" status="enabled" vcpus="10" disk="250" disk_capacity="250" memory="64"/>
 </ModelRoot>
--- a/watcher/tests/decision_engine/model/data/scenario_5_with_instance_disk_0.xml
+++ b/watcher/tests/decision_engine/model/data/scenario_5_with_instance_disk_0.xml
@@ -1,5 +1,5 @@
 <ModelRoot>
  <ComputeNode human_id="" uuid="Node_0" status="enabled" state="up" id="0" hostname="hostname_0" vcpus="4" disk="4" disk_capacity="4" memory="4">
-    <Instance state="active" human_id="" uuid="INSTANCE_0" vcpus="4" disk="0" disk_capacity="0" memory="2"/>
+    <Instance state="active" human_id="" uuid="INSTANCE_0" vcpus="4" disk="0" disk_capacity="0" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
 </ModelRoot>
--- a/watcher/tests/decision_engine/model/data/scenario_6_with_2_nodes.xml
+++ b/watcher/tests/decision_engine/model/data/scenario_6_with_2_nodes.xml
@@ -1,10 +1,10 @@
 <ModelRoot>
  <ComputeNode human_id="" uuid="Node_0" status="enabled" state="up" id="0" hostname="hostname_0" vcpus="40" disk="250" disk_capacity="250" memory="132">
-    <Instance state="active" human_id="" uuid="73b09e16-35b7-4922-804e-e8f5d9b740fc" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-    <Instance state="active" human_id="" uuid="INSTANCE_1" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
+    <Instance state="active" human_id="" uuid="73b09e16-35b7-4922-804e-e8f5d9b740fc" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+    <Instance state="active" human_id="" uuid="INSTANCE_1" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
  <ComputeNode human_id="" uuid="Node_1" status="enabled" state="up" id="1" hostname="hostname_1" vcpus="40" disk="250" disk_capacity="250" memory="132">
-    <Instance state="active" human_id="" uuid="INSTANCE_3" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-    <Instance state="active" human_id="" uuid="INSTANCE_4" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
+    <Instance state="active" human_id="" uuid="INSTANCE_3" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+    <Instance state="active" human_id="" uuid="INSTANCE_4" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
 </ModelRoot>
--- a/watcher/tests/decision_engine/model/data/scenario_7_with_2_nodes.xml
+++ b/watcher/tests/decision_engine/model/data/scenario_7_with_2_nodes.xml
@@ -1,10 +1,10 @@
 <ModelRoot>
  <ComputeNode human_id="" uuid="Node_0" status="enabled" state="up" id="0" hostname="hostname_0" vcpus="50" disk="250" disk_capacity="250" memory="132">
-    <Instance state="active" human_id="" uuid="73b09e16-35b7-4922-804e-e8f5d9b740fc" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-    <Instance state="active" human_id="" uuid="cae81432-1631-4d4e-b29c-6f3acdcde906" vcpus="15" disk="20" disk_capacity="20" memory="2"/>
+    <Instance state="active" human_id="" uuid="73b09e16-35b7-4922-804e-e8f5d9b740fc" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+    <Instance state="active" human_id="" uuid="cae81432-1631-4d4e-b29c-6f3acdcde906" vcpus="15" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
  <ComputeNode human_id="" uuid="Node_1" status="enabled" state="up" id="1" hostname="hostname_1" vcpus="50" disk="250" disk_capacity="250" memory="132">
-    <Instance state="active" human_id="" uuid="INSTANCE_3" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
-    <Instance state="active" human_id="" uuid="INSTANCE_4" vcpus="10" disk="20" disk_capacity="20" memory="2"/>
+    <Instance state="active" human_id="" uuid="INSTANCE_3" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+    <Instance state="active" human_id="" uuid="INSTANCE_4" vcpus="10" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
 </ModelRoot>
--- a/watcher/tests/decision_engine/model/data/scenario_8_with_4_nodes.xml
+++ b/watcher/tests/decision_engine/model/data/scenario_8_with_4_nodes.xml
@@ -1,16 +1,16 @@
 <ModelRoot>
  <ComputeNode hostname="hostname_0" uuid="Node_0" id="0" state="up" human_id="" status="enabled" vcpus="16" disk="250" disk_capacity="250" memory="64">
-    <Instance human_id="" state="active" uuid="INSTANCE_0" vcpus="2" disk="20" disk_capacity="20" memory="2"/>
-    <Instance human_id="" state="active" uuid="INSTANCE_1" vcpus="2" disk="20" disk_capacity="20" memory="2"/>
-    <Instance human_id="" state="active" uuid="INSTANCE_2" vcpus="2" disk="20" disk_capacity="20" memory="2"/>
+    <Instance human_id="" state="active" uuid="INSTANCE_0" vcpus="2" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+    <Instance human_id="" state="active" uuid="INSTANCE_1" vcpus="2" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+    <Instance human_id="" state="active" uuid="INSTANCE_2" vcpus="2" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
  <ComputeNode hostname="hostname_1" uuid="Node_1" id="1" state="up" human_id="" status="enabled" vcpus="16" disk="250" disk_capacity="250" memory="64">
-    <Instance human_id="" state="active" uuid="INSTANCE_3" vcpus="2" disk="20" disk_capacity="20" memory="2"/>
+    <Instance human_id="" state="active" uuid="INSTANCE_3" vcpus="2" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
  <ComputeNode hostname="hostname_2" uuid="Node_2" id="2" state="up" human_id="" status="enabled" vcpus="16" disk="250" disk_capacity="250" memory="64">
-    <Instance human_id="" state="active" uuid="INSTANCE_4" vcpus="2" disk="20" disk_capacity="20" memory="2"/>
+    <Instance human_id="" state="active" uuid="INSTANCE_4" vcpus="2" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
  <ComputeNode hostname="hostname_3" uuid="Node_3" id="3" state="up" human_id="" status="enabled" vcpus="16" disk="250" disk_capacity="250" memory="64">
-    <Instance human_id="" state="active" uuid="INSTANCE_5" vcpus="2" disk="20" disk_capacity="20" memory="2"/>
+    <Instance human_id="" state="active" uuid="INSTANCE_5" vcpus="2" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
 </ModelRoot>
--- a/watcher/tests/decision_engine/model/data/scenario_9_with_3_active_plus_1_disabled_nodes.xml
+++ b/watcher/tests/decision_engine/model/data/scenario_9_with_3_active_plus_1_disabled_nodes.xml
@@ -1,16 +1,16 @@
 <ModelRoot>
  <ComputeNode hostname="hostname_0" uuid="Node_0" id="0" state="up" human_id="" status="enabled" vcpus="16" disk="250" disk_capacity="250" memory="64">
-    <Instance human_id="" state="active" uuid="INSTANCE_0" vcpus="2" disk="20" disk_capacity="20" memory="2"/>
-    <Instance human_id="" state="active" uuid="INSTANCE_1" vcpus="2" disk="20" disk_capacity="20" memory="2"/>
-    <Instance human_id="" state="active" uuid="INSTANCE_2" vcpus="2" disk="20" disk_capacity="20" memory="2"/>
+    <Instance human_id="" state="active" uuid="INSTANCE_0" vcpus="2" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+    <Instance human_id="" state="active" uuid="INSTANCE_1" vcpus="2" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
+    <Instance human_id="" state="active" uuid="INSTANCE_2" vcpus="2" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
  <ComputeNode hostname="hostname_1" uuid="Node_1" id="1" state="up" human_id="" status="enabled" vcpus="16" disk="250" disk_capacity="250" memory="64">
-    <Instance human_id="" state="active" uuid="INSTANCE_3" vcpus="2" disk="20" disk_capacity="20" memory="2"/>
+    <Instance human_id="" state="active" uuid="INSTANCE_3" vcpus="2" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
  <ComputeNode hostname="hostname_2" uuid="Node_2" id="2" state="up" human_id="" status="enabled" vcpus="16" disk="250" disk_capacity="250" memory="64">
-    <Instance human_id="" state="active" uuid="INSTANCE_4" vcpus="2" disk="20" disk_capacity="20" memory="2"/>
+    <Instance human_id="" state="active" uuid="INSTANCE_4" vcpus="2" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
  <ComputeNode hostname="hostname_3" uuid="Node_3" id="3" state="up" human_id="" status="disabled" vcpus="16" disk="250" disk_capacity="250" memory="64">
-    <Instance human_id="" state="active" uuid="INSTANCE_5" vcpus="2" disk="20" disk_capacity="20" memory="2"/>
+    <Instance human_id="" state="active" uuid="INSTANCE_5" vcpus="2" disk="20" disk_capacity="20" memory="2" metadata='{"optimize": true,"top": "floor", "nested": {"x": "y"}}'/>
  </ComputeNode>
 </ModelRoot>
--- a/watcher/tests/decision_engine/model/faker_cluster_state.py
+++ b/watcher/tests/decision_engine/model/faker_cluster_state.py
@@ -85,6 +85,8 @@ class FakerModelCollector(base.BaseClusterDataModelCollector):
                "disk": 20,
                "disk_capacity": 20,
                "vcpus": 10,
+                "metadata":
+                    '{"optimize": true,"top": "floor","nested": {"x": "y"}}'
            }

            instance = element.Instance(**instance_attributes)
--- a/watcher/tests/decision_engine/model/test_model.py
+++ b/watcher/tests/decision_engine/model/test_model.py
@@ -18,9 +18,7 @@

 import os

-from lxml import etree
 from oslo_utils import uuidutils
-import six

 from watcher.common import exception
 from watcher.decision_engine.model import element
@@ -45,26 +43,16 @@ class TestModel(base.TestCase):

    def test_model_structure(self):
        fake_cluster = faker_cluster_state.FakerModelCollector()
-        model = fake_cluster.build_scenario_1()
+        model1 = fake_cluster.build_scenario_1()

-        self.assertEqual(5, len(model.get_all_compute_nodes()))
-        self.assertEqual(35, len(model.get_all_instances()))
-        self.assertEqual(8, len(model.edges()))
+        self.assertEqual(5, len(model1.get_all_compute_nodes()))
+        self.assertEqual(35, len(model1.get_all_instances()))
+        self.assertEqual(8, len(model1.edges()))

        expected_struct_str = self.load_data('scenario_1.xml')
-        parser = etree.XMLParser(remove_blank_text=True)
-        expected_struct = etree.fromstring(expected_struct_str, parser)
-        model_structure = etree.fromstring(model.to_string(), parser)
+        model2 = model_root.ModelRoot.from_xml(expected_struct_str)

-        normalized_expected_output = six.BytesIO()
-        normalized_model_output = six.BytesIO()
-        expected_struct.getroottree().write_c14n(normalized_expected_output)
-        model_structure.getroottree().write_c14n(normalized_model_output)
-
-        normalized_expected_struct = normalized_expected_output.getvalue()
-        normalized_model_struct = normalized_model_output.getvalue()
-
-        self.assertEqual(normalized_expected_struct, normalized_model_struct)
+        self.assertTrue(model_root.ModelRoot.is_isomorphic(model2, model1))

    def test_build_model_from_xml(self):
        fake_cluster = faker_cluster_state.FakerModelCollector()