Add support to namespaces on dynamic pollsters

Problem description
===================
The hardcoded pollsters are defined by namespaces, so they
are instantied based on the namespaces provided to the
'AgentManager'.

The dynamic pollsters, on the other hand, are always instantied,
independent of the provided namespaces.

Proposal
========
To allow operators to define in which namespaces the dynamic
pollster will be deployed, we propose to add a new configuration
'namespaces' in the dynamic pollsters yaml configuration.
This configuration will support a single entry or a list of the
namespaces that the pollster must be instantiated.

Change-Id: I39ba0c3dd312a0601e02f8cfcab7a44e585a8a7f

3 files changed, 96 insertions, 2 deletions

diff --git a/ceilometer/polling/manager.py b/ceilometer/polling/manager.py
index 6b9289d1..717d1426 100644
--- a/ceilometer/polling/manager.py
+++ b/ceilometer/polling/manager.py
@@ -253,7 +253,8 @@ class AgentManager(cotyledon.Service):
                          for namespace in namespaces)
 
         # Create dynamic pollsters
-        extensions_dynamic_pollsters = self.create_dynamic_pollsters()
+        extensions_dynamic_pollsters = self.create_dynamic_pollsters(
+            namespaces)
 
         self.extensions = list(itertools.chain(*list(extensions))) + list(
             itertools.chain(*list(extensions_fb))) + list(
@@ -291,15 +292,18 @@ class AgentManager(cotyledon.Service):
         self._keystone = None
         self._keystone_last_exception = None
 
-    def create_dynamic_pollsters(self):
+    def create_dynamic_pollsters(self, namespaces):
         """Creates dynamic pollsters
 
         This method Creates dynamic pollsters based on configurations placed on
         'pollsters_definitions_dirs'
 
+        :param namespaces: The namespaces we are running on to validate if
+                           the pollster should be instantiated or not.
         :return: a list with the dynamic pollsters defined by the operator.
         """
 
+        namespaces_set = set(namespaces)
         pollsters_definitions_dirs = self.conf.pollsters_definitions_dirs
         if not pollsters_definitions_dirs:
             LOG.info("Variable 'pollsters_definitions_dirs' not defined.")
@@ -333,6 +337,21 @@ class AgentManager(cotyledon.Service):
 
             for pollster_cfg in pollsters_cfg:
                 pollster_name = pollster_cfg['name']
+                pollster_namespaces = pollster_cfg.get(
+                    'namespaces', ['central'])
+                if isinstance(pollster_namespaces, list):
+                    pollster_namespaces = set(pollster_namespaces)
+                else:
+                    pollster_namespaces = {pollster_namespaces}
+
+                if not bool(namespaces_set & pollster_namespaces):
+                    LOG.info("The pollster [%s] is not configured to run in "
+                             "these namespaces %s, the configured namespaces "
+                             "for this pollster are %s. Therefore, we are "
+                             "skipping it.", pollster_name, namespaces_set,
+                             pollster_namespaces)
+                    continue
+
                 if pollster_name not in pollsters_definitions:
                     LOG.info("Loading dynamic pollster [%s] from file [%s].",
                              pollster_name, pollsters_definitions_file)
diff --git a/ceilometer/tests/unit/polling/test_manager.py b/ceilometer/tests/unit/polling/test_manager.py
index e805b9be..c9a1e1e1 100644
--- a/ceilometer/tests/unit/polling/test_manager.py
+++ b/ceilometer/tests/unit/polling/test_manager.py
@@ -422,6 +422,76 @@ class TestPollingAgent(BaseAgent):
         self.assertIn(60, polling_tasks.keys())
         self.assertNotIn(10, polling_tasks.keys())
 
+    @mock.patch('glob.glob')
+    @mock.patch('ceilometer.declarative.load_definitions')
+    def test_setup_polling_dynamic_pollster_namespace(self, load_mock,
+                                                      glob_mock):
+        glob_mock.return_value = ['test.yml']
+        load_mock.return_value = [{
+            'name': "test.dynamic.pollster",
+            'namespaces': "dynamic",
+            'sample_type': 'gauge',
+            'unit': 'test',
+            'endpoint_type': 'test',
+            'url_path': 'test',
+            'value_attribute': 'test'
+        }, {
+            'name': "test.compute.central.pollster",
+            'sample_type': 'gauge',
+            'namespaces': ["compute", "central"],
+            'unit': 'test',
+            'endpoint_type': 'test',
+            'url_path': 'test',
+            'value_attribute': 'test'
+        }, {
+            'name': "test.compute.pollster",
+            'namespaces': ["compute"],
+            'sample_type': 'gauge',
+            'unit': 'test',
+            'endpoint_type': 'test',
+            'url_path': 'test',
+            'value_attribute': 'test'
+        }, {
+            'name': "test.central.pollster",
+            'sample_type': 'gauge',
+            'unit': 'test',
+            'endpoint_type': 'test',
+            'url_path': 'test',
+            'value_attribute': 'test'
+        }]
+        mgr = manager.AgentManager(0, self.CONF, namespaces=['dynamic'])
+        self.assertEqual(len(mgr.extensions), 1)
+        self.assertEqual(
+            mgr.extensions[0].definitions.configurations['name'],
+            'test.dynamic.pollster')
+
+        mgr = manager.AgentManager(0, self.CONF)
+        self.assertEqual(
+            mgr.extensions[-3].definitions.configurations['name'],
+            'test.compute.central.pollster')
+        self.assertEqual(
+            mgr.extensions[-2].definitions.configurations['name'],
+            'test.compute.pollster')
+        self.assertEqual(
+            mgr.extensions[-1].definitions.configurations['name'],
+            'test.central.pollster')
+
+        mgr = manager.AgentManager(0, self.CONF, namespaces=['compute'])
+        self.assertEqual(
+            mgr.extensions[-2].definitions.configurations['name'],
+            'test.compute.central.pollster')
+        self.assertEqual(
+            mgr.extensions[-1].definitions.configurations['name'],
+            'test.compute.pollster')
+
+        mgr = manager.AgentManager(0, self.CONF, ['central'])
+        self.assertEqual(
+            mgr.extensions[-2].definitions.configurations['name'],
+            'test.compute.central.pollster')
+        self.assertEqual(
+            mgr.extensions[-1].definitions.configurations['name'],
+            'test.central.pollster')
+
     def test_setup_polling_task_same_interval(self):
         self.polling_cfg['sources'].append({
             'name': 'test_polling_1',
diff --git a/doc/source/admin/telemetry-dynamic-pollster.rst b/doc/source/admin/telemetry-dynamic-pollster.rst
index d861c07f..e60c04e8 100644
--- a/doc/source/admin/telemetry-dynamic-pollster.rst
+++ b/doc/source/admin/telemetry-dynamic-pollster.rst
@@ -198,6 +198,11 @@ attributes to define a dynamic pollster:
    executed serially, one after the other. Therefore, if the request hangs,
    all pollsters (including the non-dynamic ones) will stop executing.
 
+*  ``namespaces``: optional parameter. Defines the namespaces (running
+   ceilometer instances) where the pollster will be instantiated. This
+   parameter accepts a single string value or a list of strings. The
+   default value is `central`.
+
 The complete YAML configuration to gather data from Magnum (that has been used
 as an example) is the following: