feat: allow customization of a postrotate script

You need to signal to bind to reload log files after rotating them,
doing `rndc reconfig` is a good way of doing so.

This change allows you to actually have that in the generated logrotate
configuration

bind/files/debian/logrotate_bind

@@ -2,12 +2,18 @@
 {%- set user = salt['pillar.get']('bind:config:user', map.user) %}
 {%- set group = salt['pillar.get']('bind:config:group', map.group) %}
 {%- set mode = salt['pillar.get']('bind:config:log_mode', map.log_mode) %}
+{%- set postrotate = salt['pillar.get']('bind:logrotate:postrotate_script', "") %}
 {{ map.log_dir }}/*.log {
     rotate 7
     daily
     missingok
     notifempty
     sharedscripts
+    {%- if postrotate != "" %}
+    postrotate
+      {{ postrotate }}
+    endscript
+    {%- endif %}
     copytruncate
     compress
     create {{ mode }} {{ user }} {{ group }}

pillar.example

@@ -9,6 +9,9 @@
 ### Overrides for the defaults specified by ###
 ### map.jinja                               ###
 bind:
+  logrotate:
+    postrotate_script: >
+      rndc reconfig &>/dev/null || true
   lookup:
     pkgs:
       - bind                                      # Need to install