Purge old packages on upgrade-charm

On charm upgrade the charm may switch to py3 packages. If so, ensure
the old py2 packages are purged. If the purge occurs then restart
services.

Change-Id: I3e67d35324888522f6c138ebd74a2ea7f1a4ce05
Closes-Bug: 1803451

hooks/cinder_hooks.py

@@ -46,6 +46,7 @@ from cinder_utils import (
     scrub_old_style_ceph,
     pause_unit_helper,
     resume_unit_helper,
+    remove_old_packages,
 )
 
 from cinder_contexts import ceph_config_file
@@ -589,10 +590,15 @@ def configure_https():
 @harden()
 def upgrade_charm():
     apt_install(determine_packages(), fatal=True)
+    packages_removed = remove_old_packages()
     for rel_id in relation_ids('amqp'):
         amqp_joined(relation_id=rel_id)
     update_nrpe_config()
     scrub_old_style_ceph()
+    if packages_removed:
+        juju_log("Package purge detected, restarting services")
+        for s in services():
+            service_restart(s)
 
 
 @hooks.hook('storage-backend-relation-changed')

hooks/cinder_utils.py

@@ -375,6 +375,18 @@ def determine_purge_packages():
     return []
 
 
+def remove_old_packages():
+    '''Purge any packages that need ot be removed.
+
+    :returns: bool Whether packages were removed.
+    '''
+    installed_packages = filter_missing_packages(determine_purge_packages())
+    if installed_packages:
+        apt_purge(installed_packages, fatal=True)
+        apt_autoremove(purge=True, fatal=True)
+    return bool(installed_packages)
+
+
 def service_enabled(service):
     '''Determine if a specific cinder service is enabled in
     charm configuration.
@@ -747,10 +759,7 @@ def do_openstack_upgrade(configs=None):
     reset_os_release()
     apt_install(determine_packages(), fatal=True)
 
-    installed_packages = filter_missing_packages(determine_purge_packages())
-    if installed_packages:
-        apt_purge(installed_packages, fatal=True)
-        apt_autoremove(purge=True, fatal=True)
+    remove_old_packages()
 
     # NOTE(hopem): must do this after packages have been upgraded so that
     # we ensure that correct configs are selected for the target release.

unit_tests/test_cinder_hooks.py

@@ -59,6 +59,7 @@ TO_PATCH = [
     'CLUSTER_RES',
     'ceph_config_file',
     'update_nrpe_config',
+    'remove_old_packages',
     # charmhelpers.core.hookenv
     'config',
     'local_unit',
@@ -87,6 +88,7 @@ TO_PATCH = [
     'sync_db_with_multi_ipv6_addresses',
     'delete_keyring',
     'get_relation_ip',
+    'services',
 ]
 
 
@@ -119,11 +121,23 @@ class TestChangedHooks(CharmTestCase):
     @patch.object(hooks, 'scrub_old_style_ceph')
     @patch.object(hooks, 'amqp_joined')
     def test_upgrade_charm_no_amqp(self, _joined, _scrub_old_style_ceph):
+        self.remove_old_packages.return_value = False
         self.relation_ids.return_value = []
         hooks.hooks.execute(['hooks/upgrade-charm'])
         _joined.assert_not_called()
         _scrub_old_style_ceph.assert_called_once_with()
 
+    @patch.object(hooks, 'scrub_old_style_ceph')
+    @patch.object(hooks, 'amqp_joined')
+    def test_upgrade_charm_purge(self, _joined, _scrub_old_style_ceph):
+        self.remove_old_packages.return_value = True
+        self.services.return_value = ['cinder-api']
+        self.relation_ids.return_value = []
+        hooks.hooks.execute(['hooks/upgrade-charm'])
+        _joined.assert_not_called()
+        _scrub_old_style_ceph.assert_called_once_with()
+        self.service_restart.assert_called_once_with('cinder-api')
+
     @patch.object(hooks, 'scrub_old_style_ceph')
     @patch.object(hooks, 'amqp_joined')
     def test_upgrade_charm_with_amqp(self, _joined, _scrub_old_style_ceph):