Gate install of tmpfiles configuration

The vhost-user tmpfiles configuration is only applicable in deployments
using libvirt/kvm with nova-compute.

Ensure appropriate user and group exists before installing tmpfiles.d
configuration.

Change-Id: I471ff459e5f979cb6781193fb074f6f5f7ee967f
Closes-Bug: 1792414

hooks/neutron_ovs_utils.py

@@ -67,6 +67,8 @@ from charmhelpers.core.host import (
     service_running,
     CompareHostReleases,
     init_is_systemd,
+    group_exists,
+    user_exists,
 )
 
 from charmhelpers.fetch import (
@@ -445,7 +447,10 @@ def enable_ovs_dpdk():
 
 def install_tmpfilesd():
     '''Install systemd-tmpfiles configuration for ovs vhost-user sockets'''
-    if init_is_systemd():
+    # NOTE(jamespage): Only do this if libvirt is actually installed
+    if (init_is_systemd() and
+            user_exists('libvirt-qemu') and
+            group_exists('kvm')):
         shutil.copy('files/nova-ovs-vhost-user.conf',
                     '/etc/tmpfiles.d')
         subprocess.check_call(['systemd-tmpfiles', '--create'])

unit_tests/test_neutron_ovs_utils.py

@@ -61,6 +61,9 @@ TO_PATCH = [
     'disable_ipfix',
     'ovs_has_late_dpdk_init',
     'parse_data_port_mappings',
+    'user_exists',
+    'group_exists',
+    'init_is_systemd',
 ]
 
 head_pkg = 'linux-headers-3.15.0-5-generic'
@@ -782,6 +785,28 @@ class TestNeutronOVSUtils(CharmTestCase):
 
         self.assertTrue(self.remote_restart.called)
 
+    @patch.object(nutils, 'subprocess')
+    @patch.object(nutils, 'shutil')
+    def test_install_tmpfilesd_lxd(self, mock_shutil, mock_subprocess):
+        self.init_is_systemd.return_value = True
+        self.group_exists.return_value = False
+        self.user_exists.return_value = False
+        nutils.install_tmpfilesd()
+        mock_shutil.copy.assert_not_called()
+        mock_subprocess.check_call.assert_not_called()
+
+    @patch.object(nutils, 'subprocess')
+    @patch.object(nutils, 'shutil')
+    def test_install_tmpfilesd_libvirt(self, mock_shutil, mock_subprocess):
+        self.init_is_systemd.return_value = True
+        self.group_exists.return_value = True
+        self.user_exists.return_value = True
+        nutils.install_tmpfilesd()
+        mock_shutil.copy.assert_called_once()
+        mock_subprocess.check_call.assert_called_once_with(
+            ['systemd-tmpfiles', '--create']
+        )
+
 
 class TestDPDKBridgeBondMap(CharmTestCase):