tasks: Set systemd installation prefix

The systemd installation prefix is distro specific so add a new
systemd_utils_prefix variable in the distro files instead of using
a hardcoded value.

Change-Id: Idccb404696e1cf3b8d56f62782dc8afa86996517

tasks/lxc_cache_preparation_systemd_old.yml

@@ -63,8 +63,8 @@
 #  the following ML post resolves the bug.
 #  * https://lists.freedesktop.org/archives/systemd-devel/2015-March/029151.html
 - name: Move machined service into place
-  copy:
-    src: systemd-machined.service
+  template:
+    src: systemd-machined.service.j2
     dest: /etc/systemd/system/systemd-machined.service
   register: machined_unit
   when:

templates/systemd-machined.service.j2

@@ -13,7 +13,7 @@ Wants=machine.slice
 After=machine.slice
 
 [Service]
-ExecStart=/lib/systemd/systemd-machined
+ExecStart={{ systemd_utils_prefix }}/systemd-machined
 BusName=org.freedesktop.machine1
 CapabilityBoundingSet=CAP_KILL CAP_SYS_PTRACE CAP_SYS_ADMIN CAP_SETGID CAP_SYS_CHROOT CAP_DAC_READ_SEARCH CAP_DAC_OVERRIDE CAP_CHOWN CAP_FOWNER CAP_FSETID
 WatchdogSec=3min

vars/redhat-7.yml

@@ -14,6 +14,7 @@
 # limitations under the License.
 
 system_config_dir: "/etc/sysconfig"
+systemd_utils_prefix: "/lib/systemd"
 
 # Required rpm packages.
 lxc_hosts_distro_packages:

vars/ubuntu-16.04.yml

@@ -43,6 +43,7 @@ lxc_hosts_distro_packages:
 lxc_xz_bin: pxz
 
 system_config_dir: "/etc/default"
+systemd_utils_prefix: "/lib/systemd"
 lxc_cache_map:
   distro: ubuntu
   arch: "{{ lxc_architecture_mapping.get( ansible_architecture ) }}"