From 7f15c2f5ce230ec3d1724d924a164e6a49b8584a Mon Sep 17 00:00:00 2001
From: James Page <james.page@ubuntu.com>
Date: Mon, 15 Oct 2018 16:39:52 +0100
Subject: [PATCH] py3: deal with subordinate dependencies

Switch to marking non-leaf python-* packages as automatically
installed so that they will be purged once the last remaining
package that depends on them that was manually installed is
removed.

Force install of python3-nova-lxd for Rocky and above to ensure
that py versions are matched with python3-nova.

Change-Id: I79d528bfb7732490aa42da2158244350c03dfa59
Closes-Bug: 1797879
---
 hooks/nova_compute_utils.py           | 20 ++++++++++++++++++++
 unit_tests/test_nova_compute_utils.py |  1 +
 2 files changed, 21 insertions(+)

diff --git a/hooks/nova_compute_utils.py b/hooks/nova_compute_utils.py
index b6890783..c527eeea 100644
--- a/hooks/nova_compute_utils.py
+++ b/hooks/nova_compute_utils.py
@@ -34,6 +34,7 @@ from charmhelpers.fetch import (
     apt_install,
     apt_purge,
     apt_autoremove,
+    apt_mark,
     filter_missing_packages,
 )
 
@@ -136,7 +137,12 @@ PY3_PACKAGES = [
 
 PURGE_PACKAGES = [
     'python-nova',
+]
+
+HELD_PACKAGES = [
     'python-memcache',
+    'python-six',
+    'python-psutil',
 ]
 
 VERSION_PACKAGE = 'nova-common'
@@ -252,6 +258,7 @@ VIRT_TYPES = {
     'lxd': ['nova-compute-lxd'],
 }
 
+
 # Maps virt-type config to a libvirt URI.
 LIBVIRT_URIS = {
     'kvm': 'qemu:///system',
@@ -412,6 +419,8 @@ def determine_packages():
     if cmp_release >= 'rocky':
         packages = [p for p in packages if not p.startswith('python-')]
         packages.extend(PY3_PACKAGES)
+        if virt_type == 'lxd':
+            packages.append('python3-nova-lxd')
 
     return packages
 
@@ -424,6 +433,15 @@ def determine_purge_packages():
     return []
 
 
+def determine_held_packages():
+    '''Return a list of packages to mark as candidates for removal
+    for the current OS release'''
+    cmp_os_source = CompareOpenStackReleases(os_release('nova-common'))
+    if cmp_os_source >= 'rocky':
+        return HELD_PACKAGES
+    return []
+
+
 def migration_enabled():
     # XXX: confirm juju-core bool behavior is the same.
     return config('enable-live-migration')
@@ -600,6 +618,8 @@ def do_openstack_upgrade(configs):
         determine_purge_packages()
     )
     if installed_packages:
+        apt_mark(filter_missing_packages(determine_held_packages()),
+                 'auto')
         apt_purge(installed_packages, fatal=True)
         apt_autoremove(purge=True, fatal=True)
 
diff --git a/unit_tests/test_nova_compute_utils.py b/unit_tests/test_nova_compute_utils.py
index edc6eccb..c7825166 100644
--- a/unit_tests/test_nova_compute_utils.py
+++ b/unit_tests/test_nova_compute_utils.py
@@ -41,6 +41,7 @@ TO_PATCH = [
     'apt_update',
     'apt_purge',
     'apt_autoremove',
+    'apt_mark',
     'filter_missing_packages',
     'config',
     'os_release',