Don't restart libvirt-guests on config change

When there is a config change the service gets notfied to be
restarted, which is not required as /usr/libexec/libvirt-guests.sh
sources /etc/sysconfig/libvirt-guests on each run. As a side
effect of the service restart, instances get stopped which is bad.

In addition manage_service was bound to the enabled parameter.
This introduces manage_service to be able to manage start/stop
independent from enabled parameter.

Change-Id: Icf52a2272601401c423ae07f7b10474bdc190574
Closes-Bug: #1849264
(cherry picked from commit 0e1da12265)
(cherry picked from commit 6a0a609d57)
(cherry picked from commit a555962745)
(cherry picked from commit 9079de85fc)

manifests/compute/libvirt_guests.pp

@@ -42,12 +42,17 @@
 #   (5 minutes).
 #   Defaults to 300.
 #
+# [*manage_service*]
+#   (optional) Whether to start/stop the service
+#   Defaults to false
+#
 class nova::compute::libvirt_guests (
   $enabled                           = false,
   $package_ensure                    = 'present',
   $shutdown_timeout                  = '300',
   $on_boot                           = 'ignore',
   $on_shutdown                       = 'shutdown',
+  $manage_service                    = false,
 ) {
   include ::nova::params
   include ::nova::deps
@@ -56,9 +61,6 @@ class nova::compute::libvirt_guests (
   -> File_line<| tag == 'libvirt-guests-file_line'|>
   -> Anchor['nova::config::end']
 
-  File_line<| tag == 'libvirt-guests-file_line' |>
-  ~> Service['libvirt-guests']
-
   case $::osfamily {
     'RedHat': {
       file_line { '/etc/sysconfig/libvirt-guests ON_BOOT':
@@ -84,7 +86,7 @@ class nova::compute::libvirt_guests (
 
       nova::generic_service { 'libvirt-guests':
         enabled        => $enabled,
-        manage_service => $enabled,
+        manage_service => $manage_service,
         package_name   => $::nova::params::libvirt_guests_package_name,
         service_name   => $::nova::params::libvirt_guests_service_name,
         ensure_package => $package_ensure

spec/classes/nova_compute_libvirt_guests_spec.rb

@@ -55,6 +55,16 @@ describe 'nova::compute::libvirt_guests' do
       )}
     end
 
+    context 'while not managing service state' do
+      let :params do
+        { :enabled           => false,
+          :manage_service    => false,
+        }
+      end
+
+      it { is_expected.to contain_service('libvirt-guests').without_ensure }
+    end
+
   end
 
   on_supported_os({