Purge dhcp packages when no longer required

hooks/neutron_ovs_hooks.py

@@ -20,15 +20,12 @@ from charmhelpers.core.host import (
     restart_on_change
 )
 
-from charmhelpers.fetch import (
-    apt_purge,
-)
-
 from charmhelpers.contrib.openstack.utils import (
     os_requires_version,
 )
 
 from neutron_ovs_utils import (
+    DHCP_PACKAGES,
     DVR_PACKAGES,
     configure_ovs,
     git_install,
@@ -40,6 +37,7 @@ from neutron_ovs_utils import (
     enable_nova_metadata,
     enable_local_dhcp,
     install_packages,
+    purge_packages,
 )
 
 hooks = Hooks()
@@ -75,7 +73,7 @@ def neutron_plugin_api_changed():
     if use_dvr():
         install_packages()
     else:
-        apt_purge(DVR_PACKAGES, fatal=True)
+        purge_packages(DVR_PACKAGES)
     configure_ovs()
     CONFIGS.write_all()
     # If dvr setting has changed, need to pass that on
@@ -87,6 +85,8 @@ def neutron_plugin_api_changed():
 def neutron_plugin_joined(relation_id=None):
     if enable_local_dhcp():
         install_packages()
+    else:
+        purge_packages(DHCP_PACKAGES)
     secret = get_shared_secret() if enable_nova_metadata() else None
     rel_data = {
         'metadata-shared-secret': secret,

hooks/neutron_ovs_utils.py

@@ -45,6 +45,7 @@ from charmhelpers.core.templating import render
 
 from charmhelpers.fetch import (
     apt_install,
+    apt_purge,
     apt_update,
     filter_installed_packages,
 )
@@ -82,6 +83,7 @@ ML2_CONF = '%s/plugins/ml2/ml2_conf.ini' % NEUTRON_CONF_DIR
 EXT_PORT_CONF = '/etc/init/ext-port.conf'
 NEUTRON_METADATA_AGENT_CONF = "/etc/neutron/metadata_agent.ini"
 DVR_PACKAGES = ['neutron-l3-agent']
+DHCP_PACKAGES = ['neutron-metadata-agent', 'neutron-dhcp-agent']
 PHY_NIC_MTU_CONF = '/etc/init/os-charm-phy-nic-mtu.conf'
 TEMPLATES = 'templates/'
 
@@ -140,6 +142,16 @@ def install_packages():
     apt_install(filter_installed_packages(determine_packages()))
 
 
+def purge_packages(pkg_list):
+    purge_pkgs = []
+    required_packages = determine_packages()
+    for pkg in pkg_list:
+        if pkg not in required_packages:
+            purge_pkgs.append(pkg)
+    if purge_pkgs:
+        apt_purge(purge_pkgs, fatal=True)
+
+
 def determine_packages():
     pkgs = []
     plugin_pkgs = neutron_plugin_attribute('ovs', 'packages', 'neutron')
@@ -148,7 +160,7 @@ def determine_packages():
     if use_dvr():
         pkgs.extend(DVR_PACKAGES)
     if enable_local_dhcp():
-        pkgs.extend(['neutron-metadata-agent', 'neutron-dhcp-agent'])
+        pkgs.extend(DHCP_PACKAGES)
 
     if git_install_requested():
         pkgs.extend(BASE_GIT_PACKAGES)

unit_tests/test_neutron_ovs_hooks.py

@@ -19,7 +19,6 @@ utils.register_configs = _reg
 utils.restart_map = _map
 
 TO_PATCH = [
-    'apt_purge',
     'config',
     'CONFIGS',
     'get_shared_secret',
@@ -30,6 +29,7 @@ TO_PATCH = [
     'configure_ovs',
     'use_dvr',
     'install_packages',
+    'purge_packages',
     'enable_nova_metadata',
     'enable_local_dhcp',
 ]
@@ -137,7 +137,7 @@ class NeutronOVSHooksTests(CharmTestCase):
         self.configure_ovs.assert_called_with()
         self.assertTrue(self.CONFIGS.write_all.called)
         _plugin_joined.assert_called_with(relation_id='rid')
-        self.apt_purge.assert_called_with(['neutron-l3-agent'], fatal=True)
+        self.purge_packages.assert_called_with(['neutron-l3-agent'])
 
     @patch.object(hooks, 'git_install_requested')
     def test_neutron_plugin_joined(self, git_requested):