[hooks] config_changed checks for "sysctl". fixes LP: #1366598

config.yaml

@@ -115,3 +115,9 @@ options:
       .
       This network will be used for tenant network traffic in overlay
       networks.
+  sysctl:
+    type: string
+    default:
+    description: |
+      YAML formatted associative array of sysctl values, e.g.:
+        '{ kernel.pid_max : 4194303 }'

hooks/quantum_hooks.py

@@ -33,6 +33,7 @@ from charmhelpers.contrib.openstack.utils import (
     openstack_upgrade_available,
 )
 from charmhelpers.payload.execd import execd_preinstall
+from charmhelpers.core.sysctl import create as create_sysctl
 
 import sys
 from quantum_utils import (
@@ -78,6 +79,11 @@ def config_changed():
     global CONFIGS
     if openstack_upgrade_available(get_common_package()):
         CONFIGS = do_openstack_upgrade()
+
+    sysctl_dict = config('sysctl')
+    if sysctl_dict:
+        create_sysctl(sysctl_dict, '/etc/sysctl.d/50-quantum-gateway.conf')
+
     # Re-run joined hooks as config might have changed
     for r_id in relation_ids('shared-db'):
         db_joined(relation_id=r_id)

unit_tests/test_quantum_hooks.py

@@ -40,7 +40,8 @@ TO_PATCH = [
     'lsb_release',
     'stop_services',
     'b64decode',
-    'is_relation_made'
+    'is_relation_made',
+    'create_sysctl',
 ]
 
 
@@ -98,6 +99,7 @@ class TestQuantumHooks(CharmTestCase):
     def test_config_changed(self):
         def mock_relids(rel):
             return ['relid']
+        self.test_config.set('sysctl', '{ kernel.max_pid: "1337"}')
         self.openstack_upgrade_available.return_value = True
         self.valid_plugin.return_value = True
         self.relation_ids.side_effect = mock_relids
@@ -112,6 +114,7 @@ class TestQuantumHooks(CharmTestCase):
         self.assertTrue(_pgsql_db_joined.called)
         self.assertTrue(_amqp_joined.called)
         self.assertTrue(_amqp_nova_joined.called)
+        self.create_sysctl.assert_called()
 
     def test_config_changed_upgrade(self):
         self.openstack_upgrade_available.return_value = True