[gnuoy, r=james-page] This change sets the requests hugepage value down the relation with the neutron plugin subordinate charm. The reason for this is so that the subordinate can react to a change in that value and restart any services. This is a feature that was requested by cisco for the cisco-vpp charm

hooks/nova_compute_hooks.py

@@ -70,6 +70,7 @@ from nova_compute_utils import (
     install_hugepages,
     REQUIRED_INTERFACES,
     check_optional_relations,
+    get_hugepage_number,
 )
 
 from charmhelpers.contrib.network.ip import (
@@ -149,6 +150,9 @@ def config_changed():
     for rid in relation_ids('zeromq-configuration'):
         zeromq_configuration_relation_joined(rid)
 
+    for rid in relation_ids('neutron-plugin'):
+        neutron_plugin_joined(rid)
+
     if is_relation_made("nrpe-external-master"):
         update_nrpe_config()
 
@@ -377,6 +381,12 @@ def update_nrpe_config():
     nrpe_setup.write()
 
 
+@hooks.hook('neutron-plugin-relation-joined')
+def neutron_plugin_joined(relid=None):
+    relation_set(relation_id=relid,
+                 hugepage_number=get_hugepage_number())
+
+
 @hooks.hook('neutron-plugin-relation-changed')
 @restart_on_change(restart_map())
 def neutron_plugin_changed():

hooks/nova_compute_utils.py

@@ -802,13 +802,11 @@ def git_post_install(projects_yaml):
     apt_install(LATE_GIT_PACKAGES, fatal=True)
 
 
-def install_hugepages():
+def get_hugepage_number():
-    """ Configure hugepages """
-    hugepage_config = config('hugepages')
-    if hugepage_config:
     # TODO: defaults to 2M - this should probably be configurable
     #       and support multiple pool sizes - e.g. 2M and 1G.
     hugepage_size = 2048
+    hugepage_config = config('hugepages')
     if hugepage_config.endswith('%'):
         import psutil
         mem = psutil.virtual_memory()
@@ -817,12 +815,19 @@ def install_hugepages():
         hugepages = int((mem.total * hugepage_multiplier) / hugepage_size)
     else:
         hugepages = int(hugepage_config)
+    return hugepages
+
+
+def install_hugepages():
+    """ Configure hugepages """
+    hugepage_config = config('hugepages')
+    if hugepage_config:
         mnt_point = '/run/hugepages/kvm'
         hugepage_support(
             'nova',
             mnt_point=mnt_point,
             group='root',
-            nr_hugepages=hugepages,
+            nr_hugepages=get_hugepage_number(),
             mount=False,
             set_shmmax=True,
         )

unit_tests/test_nova_compute_hooks.py

@@ -124,8 +124,10 @@ class NovaComputeRelationsTests(CharmTestCase):
         hooks.config_changed()
         self.assertFalse(self.do_openstack_upgrade.called)
 
+    @patch.object(hooks, 'neutron_plugin_joined')
     @patch.object(hooks, 'compute_joined')
-    def test_config_changed_with_migration(self, compute_joined):
+    def test_config_changed_with_migration(self, compute_joined,
+                                           neutron_plugin_joined):
         self.git_install_requested.return_value = False
         self.migration_enabled.return_value = True
         _zmq_joined = self.patch('zeromq_configuration_relation_joined')
@@ -143,8 +145,10 @@ class NovaComputeRelationsTests(CharmTestCase):
         self.assertTrue(self.initialize_ssh_keys.called)
         self.assertTrue(_zmq_joined.called)
 
+    @patch.object(hooks, 'neutron_plugin_joined')
     @patch.object(hooks, 'compute_joined')
-    def test_config_changed_with_resize(self, compute_joined):
+    def test_config_changed_with_resize(self, compute_joined,
+                                        neutron_plugin_joined):
         self.git_install_requested.return_value = False
         self.test_config.set('enable-resize', True)
         _zmq_joined = self.patch('zeromq_configuration_relation_joined')
@@ -162,8 +166,10 @@ class NovaComputeRelationsTests(CharmTestCase):
         self.enable_shell.assert_called_with(user='nova')
         self.assertTrue(_zmq_joined.called)
 
+    @patch.object(hooks, 'neutron_plugin_joined')
     @patch.object(hooks, 'compute_joined')
-    def test_config_changed_without_resize(self, compute_joined):
+    def test_config_changed_without_resize(self, compute_joined,
+                                           neutron_plugin_joined):
         self.git_install_requested.return_value = False
         self.test_config.set('enable-resize', False)
         _zmq_joined = self.patch('zeromq_configuration_relation_joined')