Add feature-complete /domain/clock support

Feature reference: https://libvirt.org/formatdomain.html#time-keeping

docs/configuration.markdown

@@ -1046,9 +1046,18 @@ end
 
 ## Clock
 
-Clock offset can be specified via `libvirt.clock_offset`. (Default is utc)
+The clock can be configured using one of the following methods:
 
-Additionally timers can be specified via `libvirt.clock_timer`.
+* Set nothing, and the clock will default to UTC.
+* Set `libvirt.clock_offset` to 'utc' or 'localtime' by assigning the respective values.
+* To set the clock to a different timezone, assign the timezone name to `libvirt.clock_timezone`.
+* To set the clock to the same absolute time whenever the VM starts, set `libvirt.clock_absolute`.
+  The value format is that of an epoch timestamp.
+* To set the clock at an arbitrary offset to realtime, use `libvirt.clock_adjustment`.
+  Specify the offset adjustment in seconds.  By default, the clock offset is relative to UTC,
+  but this can be changed by setting `libvirt.clock_basis` to 'localtime'.
+
+In addition to the above, timers can be specified via `libvirt.clock_timer`.
 Available options for timers are: name, track, tickpolicy, frequency, mode,  present
 
 ```ruby

lib/vagrant-libvirt/action/create_domain.rb

@@ -36,7 +36,11 @@ module VagrantPlugins
           @nodeset = config.nodeset
           @features = config.features
           @features_hyperv = config.features_hyperv
+          @clock_absolute = config.clock_absolute
+          @clock_adjustment = config.clock_adjustment
+          @clock_basis = config.clock_basis
           @clock_offset = config.clock_offset
+          @clock_timezone = config.clock_timezone
           @clock_timers = config.clock_timers
           @launchsecurity_data = config.launchsecurity_data
           @shares = config.shares
@@ -236,7 +240,15 @@ module VagrantPlugins
               env[:ui].info(" -- Feature (HyperV):  name=#{feature[:name]}, state=#{feature[:state]}")
             end
           end
-          env[:ui].info(" -- Clock offset:      #{@clock_offset}")
+          if not @clock_absolute.nil?
+            env[:ui].info(" -- Clock absolute:    #{@clock_absolute}")
+          elsif not @clock_adjustment.nil?
+            env[:ui].info(" -- Clock adjustment:  #{@clock_adjustment}")
+          elsif not @clock_timezone.nil?
+            env[:ui].info(" -- Clock timezone:    #{@clock_timezone}")
+          else
+            env[:ui].info(" -- Clock offset:      #{@clock_offset}")
+          end
           @clock_timers.each do |timer|
             env[:ui].info(" -- Clock timer:       #{timer.map { |k,v| "#{k}=#{v}"}.join(', ')}")
           end

lib/vagrant-libvirt/action/start_domain.rb

@@ -166,12 +166,29 @@ module VagrantPlugins
             xml_descr.delete_element('/domain/cpu')
           end
 
-          # Clock
+          # Clock - can change in complicated ways, so just build a new clock and compare
+          newclock = REXML::Element.new('newclock')
+          if not config.clock_absolute.nil?
+            newclock.add_attribute('offset', 'absolute')
+            newclock.add_attribute('start', config.clock_absolute)
+          elsif not config.clock_adjustment.nil?
+            newclock.add_attribute('offset', 'variable')
+            newclock.add_attribute('basis', config.clock_basis)
+            newclock.add_attribute('adjustment', config.clock_adjustment)
+          elsif not config.clock_timezone.nil?
+            newclock.add_attribute('offset', 'timezone')
+            newclock.add_attribute('timezone', config.clock_timezone)
+          else
+            newclock.add_attribute('offset', config.clock_offset)
+          end
           clock = REXML::XPath.first(xml_descr, '/domain/clock')
-          if clock.attributes['offset'] != config.clock_offset
+          if clock.attributes != newclock.attributes
-            @logger.debug "clock offset changed"
+            @logger.debug "clock definition changed"
             descr_changed = true
-            clock.attributes['offset'] = config.clock_offset
+            clock.attributes.clear
+            newclock.attributes.each do |attr, value|
+              clock.add_attribute(attr, value)
+            end
           end
 
           # clock timers - because timers can be added/removed, just rebuild and then compare

lib/vagrant-libvirt/config.rb

@@ -98,7 +98,11 @@ module VagrantPlugins
       attr_accessor :shares
       attr_accessor :features
       attr_accessor :features_hyperv
+      attr_accessor :clock_absolute
+      attr_accessor :clock_adjustment
+      attr_accessor :clock_basis
       attr_accessor :clock_offset
+      attr_accessor :clock_timezone
       attr_accessor :clock_timers
       attr_accessor :launchsecurity_data
       attr_accessor :numa_nodes
@@ -278,7 +282,11 @@ module VagrantPlugins
         @shares            = UNSET_VALUE
         @features          = UNSET_VALUE
         @features_hyperv   = UNSET_VALUE
+        @clock_absolute    = UNSET_VALUE
+        @clock_adjustment  = UNSET_VALUE
+        @clock_basis       = UNSET_VALUE
         @clock_offset      = UNSET_VALUE
+        @clock_timezone    = UNSET_VALUE
         @clock_timers      = []
         @launchsecurity_data = UNSET_VALUE
         @numa_nodes        = UNSET_VALUE
@@ -1002,7 +1010,11 @@ module VagrantPlugins
         @shares = nil if @shares == UNSET_VALUE
         @features = ['acpi','apic','pae'] if @features == UNSET_VALUE
         @features_hyperv = [] if @features_hyperv == UNSET_VALUE
+        @clock_absolute = nil if @clock_absolute == UNSET_VALUE
+        @clock_adjustment = nil if @clock_adjustment == UNSET_VALUE
+        @clock_basis = 'utc' if @clock_basis == UNSET_VALUE
         @clock_offset = 'utc' if @clock_offset == UNSET_VALUE
+        @clock_timezone = nil if @clock_timezone == UNSET_VALUE
         @clock_timers = [] if @clock_timers == UNSET_VALUE
         @launchsecurity_data = nil if @launchsecurity_data == UNSET_VALUE
         @numa_nodes = @numa_nodes == UNSET_VALUE ? nil : _generate_numa

lib/vagrant-libvirt/templates/domain.xml.erb

@@ -132,7 +132,15 @@
     </hyperv>
 <%- end -%>
   </features>
+<%- if not @clock_absolute.nil? -%>
+  <clock offset='absolute' start='<%= @clock_absolute %>'>
+<%- elsif not @clock_adjustment.nil? -%>
+  <clock offset='variable' basis='<%= @clock_basis %>' adjustment='<%= @clock_adjustment %>'>
+<%- elsif not @clock_timezone.nil? -%>
+  <clock offset='timezone' timezone='<%= @clock_timezone %>'>
+<%- else -%>
   <clock offset='<%= @clock_offset %>'>
+<%- end -%>
 <%- @clock_timers.each do |clock_timer| -%>
     <timer<% clock_timer.each do |attr, value| %> <%= attr %>='<%= value %>'<% end %>/>
 <%- end -%>

spec/unit/templates/domain_all_settings.xml

@@ -47,7 +47,7 @@
       <spinlocks state='on' retries='4096' />
     </hyperv>
   </features>
-  <clock offset='variable'>
+  <clock offset='variable' basis='localtime' adjustment='-31536000'>
     <timer name='t1'/>
     <timer name='t2' track='b' tickpolicy='c' frequency='d' mode='e' present='yes'/>
   </clock>

spec/unit/templates/domain_spec.rb

@@ -62,7 +62,8 @@ describe 'templates/domain' do
       domain.cpu_mode = 'custom'
       domain.cpu_feature(name: 'AAA', policy: 'required')
       domain.hyperv_feature(name: 'BBB', state: 'on')
-      domain.clock_offset = 'variable'
+      domain.clock_adjustment = -(365 * 24 * 60 * 60)
+      domain.clock_basis = 'localtime'
       domain.clock_timer(name: 't1')
       domain.clock_timer(name: 't2', track: 'b', tickpolicy: 'c', frequency: 'd', mode: 'e',  present: 'yes')
       domain.hyperv_feature(name: 'spinlocks', state: 'on', retries: '4096')