py3: Switch to using Python 3 for OpenStack Rocky

Switch nova installation to use Python 3 for OpenStack Rocky.

Purge python- packages on upgrade.

Change-Id: I7839c823d51f6a3d166157be19f2e93b8dd72305
Depends-On: Ic5e96336b6a2ca474fc28d358553c6a05e1a75ce

hooks/nova_compute_utils.py

@@ -32,6 +32,9 @@ from charmhelpers.fetch import (
     apt_update,
     apt_upgrade,
     apt_install,
+    apt_purge,
+    apt_autoremove,
+    filter_missing_packages,
 )
 
 from charmhelpers.core.fstab import Fstab
@@ -126,6 +129,16 @@ BASE_PACKAGES = [
     'xfsprogs',
 ]
 
+PY3_PACKAGES = [
+    'python3-nova',
+    'python3-memcache',
+]
+
+PURGE_PACKAGES = [
+    'python-nova',
+    'python-memcache',
+]
+
 VERSION_PACKAGE = 'nova-common'
 
 DEFAULT_INSTANCE_PATH = '/var/lib/nova/instances'
@@ -370,6 +383,9 @@ def determine_packages_arch():
 
 
 def determine_packages():
+    release = os_release('nova-common')
+    cmp_release = CompareOpenStackReleases(release)
+
     packages = [] + BASE_PACKAGES
 
     net_manager = network_manager()
@@ -393,9 +409,21 @@ def determine_packages():
 
     packages.extend(determine_packages_arch())
 
+    if cmp_release >= 'rocky':
+        packages = [p for p in packages if not p.startswith('python-')]
+        packages.extend(PY3_PACKAGES)
+
     return packages
 
 
+def determine_purge_packages():
+    '''Return a list of packages to purge for the current OS release'''
+    cmp_os_source = CompareOpenStackReleases(os_release('nova-common'))
+    if cmp_os_source >= 'rocky':
+        return PURGE_PACKAGES
+    return []
+
+
 def migration_enabled():
     # XXX: confirm juju-core bool behavior is the same.
     return config('enable-live-migration')
@@ -568,6 +596,13 @@ def do_openstack_upgrade(configs):
     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)
+
     configs.set_release(openstack_release=new_os_rel)
     configs.write_all()
     if not is_unit_paused_set():

tox.ini

@@ -67,7 +67,7 @@ basepython = python2.7
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 commands =
-    bundletester -vl DEBUG -r json -o func-results.json gate-basic-bionic-queens --no-destroy
+    bundletester -vl DEBUG -r json -o func-results.json gate-basic-bionic-rocky --no-destroy
 
 [testenv:func27-dfs]
 # Charm Functional Test

unit_tests/test_nova_compute_utils.py

@@ -39,6 +39,9 @@ VIRSH_NET_LIST = """ Name                 State      Autostart     Persistent
 TO_PATCH = [
     'apt_install',
     'apt_update',
+    'apt_purge',
+    'apt_autoremove',
+    'filter_missing_packages',
     'config',
     'os_release',
     'log',
@@ -119,6 +122,7 @@ class NovaComputeUtilsTests(CharmTestCase):
     @patch('platform.machine')
     def test_determine_packages_neutron(self, machine, net_man,
                                         n_plugin, en_meta):
+        self.os_release.return_value = 'ocata'
         en_meta.return_value = (False, None)
         net_man.return_value = 'neutron'
         n_plugin.return_value = 'ovs'
@@ -128,6 +132,27 @@ class NovaComputeUtilsTests(CharmTestCase):
         ex = utils.BASE_PACKAGES + ['nova-compute-kvm']
         self.assertTrue(ex == result)
 
+    @patch.object(utils, 'nova_metadata_requirement')
+    @patch.object(utils, 'neutron_plugin')
+    @patch.object(utils, 'network_manager')
+    @patch('platform.machine')
+    def test_determine_packages_neutron_rocky(self, machine, net_man,
+                                              n_plugin, en_meta):
+        self.os_release.return_value = 'rocky'
+        en_meta.return_value = (False, None)
+        net_man.return_value = 'neutron'
+        n_plugin.return_value = 'ovs'
+        machine.return_value = 'x86_64'
+        self.relation_ids.return_value = []
+        result = utils.determine_packages()
+        ex = (
+            [p for p in utils.BASE_PACKAGES
+             if not p.startswith('python-')] +
+            ['nova-compute-kvm'] +
+            utils.PY3_PACKAGES
+        )
+        self.assertEqual(ex, result)
+
     @patch.object(utils, 'nova_metadata_requirement')
     @patch.object(utils, 'neutron_plugin')
     @patch.object(utils, 'network_manager')
@@ -135,6 +160,7 @@ class NovaComputeUtilsTests(CharmTestCase):
     def test_determine_packages_neutron_aarch64_xenial(self, machine,
                                                        net_man, n_plugin,
                                                        en_meta):
+        self.os_release.return_value = 'ocata'
         self.lsb_release.return_value = {
             'DISTRIB_CODENAME': 'xenial'
         }
@@ -154,6 +180,7 @@ class NovaComputeUtilsTests(CharmTestCase):
     def test_determine_packages_neutron_aarch64_trusty(self, machine,
                                                        net_man, n_plugin,
                                                        en_meta):
+        self.os_release.return_value = 'ocata'
         self.lsb_release.return_value = {
             'DISTRIB_CODENAME': 'trusty'
         }
@@ -172,6 +199,7 @@ class NovaComputeUtilsTests(CharmTestCase):
     @patch('platform.machine')
     def test_determine_packages_neutron_ceph(self, machine,
                                              net_man, n_plugin, en_meta):
+        self.os_release.return_value = 'ocata'
         en_meta.return_value = (False, None)
         net_man.return_value = 'neutron'
         n_plugin.return_value = 'ovs'
@@ -186,6 +214,7 @@ class NovaComputeUtilsTests(CharmTestCase):
     @patch.object(utils, 'network_manager')
     def test_determine_packages_metadata(self, net_man,
                                          n_plugin, en_meta):
+        self.os_release.return_value = 'ocata'
         en_meta.return_value = (True, None)
         net_man.return_value = 'bob'
         n_plugin.return_value = 'ovs'