Skip sysctl configuration in containers

Some testing use cases make use of containers to host nova-compute;
sysctl options can't be tweaked in this use case so detect and
skip if executing in a container.

Change-Id: I9ff894e728e46b229068e91a290b84cde73eb09c

hooks/nova_compute_hooks.py

@@ -49,6 +49,7 @@ from charmhelpers.core.host import (
     service_stop,
     write_file,
     umount,
+    is_container,
 )
 from charmhelpers.fetch import (
     apt_install,
@@ -181,7 +182,7 @@ def config_changed():
             send_remote_restart = True
 
     sysctl_settings = config('sysctl')
-    if sysctl_settings:
+    if sysctl_settings and not is_container():
         create_sysctl(sysctl_settings, '/etc/sysctl.d/50-nova-compute.conf')
 
     remove_libvirt_network('default')

unit_tests/test_nova_compute_hooks.py

@@ -54,6 +54,7 @@ TO_PATCH = [
     'filter_installed_packages',
     'restart_on_change',
     'service_restart',
+    'is_container',
     # charmhelpers.contrib.openstack.utils
     'configure_installation_source',
     'openstack_upgrade_available',
@@ -110,6 +111,7 @@ class NovaComputeRelationsTests(CharmTestCase):
             MagicMock(side_effect=lambda pkgs: pkgs)
         self.gethostname.return_value = 'testserver'
         self.get_relation_ip.return_value = '10.0.0.50'
+        self.is_container.return_value = False
 
     def test_install_hook(self):
         repo = 'cloud:precise-grizzly'
@@ -222,6 +224,17 @@ class NovaComputeRelationsTests(CharmTestCase):
             '{foo : bar}',
             '/etc/sysctl.d/50-nova-compute.conf')
 
+    @patch.object(hooks, 'compute_joined')
+    def test_config_changed_with_sysctl_in_container(self, compute_joined):
+        self.migration_enabled.return_value = False
+        self.is_container.return_value = True
+        self.test_config.set(
+            'sysctl',
+            '{foo : bar}'
+        )
+        hooks.config_changed()
+        self.create_sysctl.assert_not_called()
+
     @patch.object(hooks, 'compute_joined')
     def test_config_changed_no_nrpe(self, compute_joined):
         self.openstack_upgrade_available.return_value = False