From ff960140447a3ef92e054ae4df66d5393dc8efde Mon Sep 17 00:00:00 2001
From: Liam Young <liam.young@canonical.com>
Date: Thu, 15 Nov 2018 14:12:22 +0000
Subject: [PATCH] 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: I215223b41fb2ab6a31df101b5314e6b0859d8322
Closes-Bug: 1803451
---
 hooks/ceilometer_hooks.py |  9 +++++++++
 hooks/ceilometer_utils.py | 17 +++++++++++++----
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/hooks/ceilometer_hooks.py b/hooks/ceilometer_hooks.py
index a4cd77d..ffb159c 100755
--- a/hooks/ceilometer_hooks.py
+++ b/hooks/ceilometer_hooks.py
@@ -28,6 +28,9 @@ from charmhelpers.core.hookenv import (
     status_set,
     relation_ids,
 )
+from charmhelpers.core.host import (
+    service_restart
+)
 from charmhelpers.contrib.openstack.utils import (
     pausable_restart_on_change as restart_on_change,
     is_unit_paused_set,
@@ -43,6 +46,7 @@ from ceilometer_utils import (
     get_packages,
     pause_unit_helper,
     resume_unit_helper,
+    remove_old_packages,
 )
 from charmhelpers.contrib.charmsupport import nrpe
 
@@ -81,6 +85,11 @@ def upgrade_charm():
     apt_install(
         filter_installed_packages(get_packages()),
         fatal=True)
+    packages_removed = remove_old_packages()
+    if packages_removed and not is_unit_paused_set():
+        log("Package purge detected, restarting services", "INFO")
+        for s in services():
+            service_restart(s)
     # NOTE(jamespage): Ensure any changes to nova presented data are made
     #                  during charm upgrades.
     for rid in relation_ids('nova-ceilometer'):
diff --git a/hooks/ceilometer_utils.py b/hooks/ceilometer_utils.py
index 2a84a09..3d3262c 100644
--- a/hooks/ceilometer_utils.py
+++ b/hooks/ceilometer_utils.py
@@ -152,6 +152,18 @@ 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 restart_map():
     '''
     Determine the correct resource map to be passed to
@@ -213,10 +225,7 @@ def do_openstack_upgrade(configs):
     # openstack-origin which would not be present in a subordinate.
     apt_install(get_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()
 
     # set CONFIGS to load templates from new release
     configs.set_release(openstack_release=new_os_rel)