puppet: Allow choice of timesync tool.

docs/production/deployment.md

@@ -625,6 +625,14 @@ you will need to add **`zulip::apache_sso`** to the list.
 Set to true if enabling the [multi-language PGroonga search
 extension](../subsystems/full-text-search.md#multi-language-full-text-search).
 
+#### `timesync`
+
+What time synchronization daemon to use; defaults to `chrony`, but also supports
+`ntpd` and `none`. Installations should not adjust this unless they are aligning
+with a fleet-wide standard of `ntpd`. `none` is only reasonable in containers
+like LXC which do not allow adjustment of the clock; a Zulip server will not
+function correctly without an accurate clock.
+
 ### `[deployment]`
 
 #### `deploy_options`

puppet/zulip/manifests/profile/base.pp

@@ -3,6 +3,7 @@
 # This class should only be included by classes that are intended to
 # be able to be deployed on their own host.
 class zulip::profile::base {
+  include zulip::timesync
   include zulip::common
   case $::os['family'] {
     'Debian': {
@@ -28,8 +29,6 @@ class zulip::profile::base {
         'procps',
         # Used to read /etc/zulip/zulip.conf for `zulipconf` Puppet function
         'crudini',
-        # Accurate time is essential
-        'chrony',
         # Used for tools like sponge
         'moreutils',
         # Nagios monitoring plugins
@@ -49,7 +48,6 @@ class zulip::profile::base {
         'curl',
         'jq',
         'crudini',
-        'chrony',
         'moreutils',
         'nmap-ncat',
         'nagios-plugins',  # there is no dummy package on CentOS 7
@@ -60,8 +58,6 @@ class zulip::profile::base {
       fail('osfamily not supported')
     }
   }
-  package { 'ntp': ensure => purged, before => Package['chrony'] }
-  service { 'chrony': require => Package['chrony'] }
   package { $base_packages: ensure => installed }
 
   group { 'zulip':

puppet/zulip/manifests/timesync.pp

@@ -0,0 +1,23 @@
+# @summary Allows configuration of timesync tool.
+class zulip::timesync {
+  $timesync = zulipconf('machine', 'timesync', 'chrony')
+
+  case $timesync {
+    'chrony': {
+      package { 'ntp': ensure => purged, before => Package['chrony'] }
+      package { 'chrony': ensure => installed }
+      service { 'chrony': require => Package['chrony'] }
+    }
+    'ntpd': {
+      package { 'chrony': ensure => purged, before => Package['ntp'] }
+      package { 'ntp': ensure => installed }
+      service { 'ntp': require => Package['ntp'] }
+    }
+    'none': {
+      package { ['ntp', 'chrony']: ensure => purged }
+    }
+    default: {
+      fail('Unknown timesync tool: $timesync')
+    }
+  }
+}