sysctl: skip application when running in container

This charm is used in containers when deploying Octavia; sysctl
can't be updated from within a LXD container, so skip the call
to apply sysctl configuration if the unit is running in a
container of any sort.

Change-Id: If3c40fa6c8b6e5448293caf726088d152f6eeee8

hooks/neutron_ovs_hooks.py

@@ -39,6 +39,10 @@ from charmhelpers.core.hookenv import (
 
 from charmhelpers.core.sysctl import create as create_sysctl
 
+from charmhelpers.core.host import (
+    is_container,
+)
+
 from neutron_ovs_utils import (
     DHCP_PACKAGES,
     DVR_PACKAGES,
@@ -120,7 +124,7 @@ def config_changed():
         request_nova_compute_restart = True
 
     sysctl_settings = config('sysctl')
-    if sysctl_settings:
+    if not is_container() and sysctl_settings:
         create_sysctl(sysctl_settings,
                       '/etc/sysctl.d/50-openvswitch.conf')
 

unit_tests/test_neutron_ovs_hooks.py

@@ -51,6 +51,7 @@ TO_PATCH = [
     'install_tmpfilesd',
     'purge_packages',
     'determine_purge_packages',
+    'is_container',
 ]
 NEUTRON_CONF_DIR = "/etc/neutron"
 
@@ -63,6 +64,7 @@ class NeutronOVSHooksTests(CharmTestCase):
         super(NeutronOVSHooksTests, self).setUp(hooks, TO_PATCH)
 
         self.config.side_effect = self.test_config.get
+        self.is_container.return_value = False
         hooks.hooks._config_save = False
 
     def _call_hook(self, hookname):
@@ -122,6 +124,15 @@ class NeutronOVSHooksTests(CharmTestCase):
             '{foo : bar}',
             '/etc/sysctl.d/50-openvswitch.conf')
 
+    def test_config_changed_sysctl_container(self):
+        self.test_config.set(
+            'sysctl',
+            '{foo : bar}'
+        )
+        self.is_container.return_value = True
+        self._call_hook('config-changed')
+        self.create_sysctl.assert_not_called()
+
     @patch.object(hooks, 'neutron_plugin_joined')
     def test_config_changed_rocky_upgrade(self, _plugin_joined):
         self.determine_purge_packages.return_value = ['python-neutron']