Make clock offset configurable

Requested in PR feedback; this allows offset to be set per site and
overriden per instance.

Author: goetzk

README.md

@@ -36,6 +36,9 @@ Role Variables
 - `libvirt_vm_virsh_default_env`: Variables contained within this dictionary are
   added to the environment used when executing virsh commands.
 
+- `libvirt_vm_clock_offset`. If defined the instances clock offset is set to
+  the provided value. When undefined sync is set to `localtime`.
+
 - `libvirt_vms`: list of VMs to be created/destroyed. Each one may have the
   following attributes:
 
@@ -55,6 +58,8 @@ Role Variables
       `libvirt_vm_engine` is `kvm`, otherwise `host-model`. Can be set to none
       to not configure a cpu mode.
 
+    - `clock_offset`: Overrides default set in `libvirt_vm_clock_offset`
+
     - `volumes`: a list of volumes to attach to the VM.  Each volume is
       defined with the following dict:
         - `pool`: Name or UUID of the storage pool from which the volume should be

defaults/main.yml

@@ -35,6 +35,11 @@ libvirt_vm_engine:
 # correct emulator to use.
 libvirt_vm_emulator:
 
+# Default value for clock syncing. The default (false) uses <clock sync="localtime">
+# to configure the instances clock synchronisation. Change to a timezone to make
+# configuration use <clock offset="specified offset">
+libvirt_vm_clock_offset: False
+
 # A list of specifications of VMs to be created.
 # For backwards compatibility, libvirt_vms defaults to a singleton list using
 # the values of the deprecated variables below.

templates/vm.xml.j2

@@ -2,7 +2,11 @@
   <name>{{ vm.name }}</name>
   <memory>{{ vm.memory_mb | int * 1024 }}</memory>
   <vcpu>{{ vm.vcpus }}</vcpu>
+  {% if vm.clock_offset |default({{ libvirt_vm_clock_offset }}) %}
   <clock offset="{{ vm.clock_offset }}"/>
+  {% else %}
+  <clock sync="localtime"/>
+  {% endif %}
   <on_poweroff>destroy</on_poweroff>
   <on_reboot>restart</on_reboot>
   <on_crash>destroy</on_crash>