[billy-olsen,r=] Specify os_region_name based on the region.

This ensures that the region is configured within the cinder.conf file.

Partially-Closes-Bug: LP#1468306

hooks/cinder_contexts.py

@@ -154,3 +154,18 @@ class CinderSubordinateConfigContext(SubordinateConfigContext):
                 "backends configured.", level=WARNING)
 
         return ctxt
+
+
+class RegionContext(OSContextGenerator):
+    """Provides context data regarding the region the service is in.
+
+    This context provides the region that is configured by the admin via the
+    region option in the config settings for the charm. If no region config
+    is available, then this will provide an empty context.
+    """
+    def __call__(self):
+        region = config('region')
+        if region:
+            return {'region': region}
+        else:
+            return {}

hooks/cinder_utils.py

@@ -203,7 +203,8 @@ CONFIG_FILES = OrderedDict([
                               service='cinder',
                               service_user='cinder'),
                           context.BindHostContext(),
-                          context.WorkerConfigContext()],
+                          context.WorkerConfigContext(),
+                          cinder_contexts.RegionContext()],
         'services': ['cinder-api', 'cinder-volume', 'cinder-backup',
                      'cinder-scheduler', 'haproxy']
     }),

templates/cinder.conf

@@ -57,6 +57,10 @@ glance_api_servers = {{ glance_api_servers }}
 glance_api_version = {{ glance_api_version }}
 {% endif -%}
 
+{% if region -%}
+os_region_name = {{ region }}
+{% endif -%}
+
 {% if user_config_flags -%}
 {% for key, value in user_config_flags.iteritems() -%}
 {{ key }} = {{ value }}

templates/icehouse/cinder.conf

@@ -48,6 +48,10 @@ glance_api_servers = {{ glance_api_servers }}
 glance_api_version = {{ glance_api_version }}
 {% endif -%}
 
+{% if region -%}
+os_region_name = {{ region }}
+{% endif -%}
+
 {% if user_config_flags -%}
 {% for key, value in user_config_flags.iteritems() -%}
 {{ key }} = {{ value }}

templates/kilo/cinder.conf

@@ -45,6 +45,10 @@ glance_api_servers = {{ glance_api_servers }}
 glance_api_version = {{ glance_api_version }}
 {% endif -%}
 
+{% if region -%}
+os_region_name = {{ region }}
+{% endif -%}
+
 {% if user_config_flags -%}
 {% for key, value in user_config_flags.iteritems() -%}
 {{ key }} = {{ value }}

unit_tests/test_cinder_contexts.py

@@ -341,3 +341,8 @@ class TestCinderContext(CharmTestCase):
                                    u'cinder.volume.drivers.OtherDriver']]}}
 
         self.assertEquals(ctxt, exp)
+
+    def test_region_context(self):
+        self.config.return_value = 'two'
+        ctxt = contexts.RegionContext()()
+        self.assertEqual('two', ctxt['region'])