Implemented GMR plugin to show CDM structures

In this changeset, I implemented a small GMR plugin that converts
the cluster data model structure into an XML structure.

Change-Id: I75548952635a0aa3c7dbd6d068831b5765a5db1a
Closes-Bug: #1620551

watcher/decision_engine/gmr.py

@@ -0,0 +1,48 @@
+# -*- encoding: utf-8 -*-
+# Copyright (c) 2016 b<>com
+#
+# Authors: Vincent FRANCOISE <vincent.francoise@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_reports import guru_meditation_report as gmr
+
+from watcher._i18n import _
+from watcher.decision_engine.model.collector import manager
+
+
+def register_gmr_plugins():
+    """Register GMR plugins that are specific to watcher-decision-engine."""
+    gmr.TextGuruMeditation.register_section(_('CDMCs'), show_models)
+
+
+def show_models():
+    """Create a formatted output of all the CDMs
+
+    Mainly used as a Guru Meditation Report (GMR) plugin
+    """
+    mgr = manager.CollectorManager()
+
+    output = []
+    for name, cdmc in mgr.get_collectors().items():
+        output.append("")
+        output.append("~" * len(name))
+        output.append(name)
+        output.append("~" * len(name))
+        output.append("")
+
+        cdmc_struct = cdmc.cluster_data_model.to_string()
+        output.append(cdmc_struct)
+
+    return "\n".join(output)