make journald_sync_interval only applicable to persistent mode

README.md

@@ -56,7 +56,9 @@ unless otherwise indicated.
 
 - `journald_sync_interval` - integer variable, in minutes, configures the time
   span after which journald synchronizes the currently used journal file to
-  disk. By default role doesn't alter currently used value.
+  disk. By default role doesn't alter currently used value.  This setting is
+  only applicable for `journald_persistent: true`.  You will get a warning if
+  set otherwise.
 
 - `journald_forward_to_syslog` - boolean variable, control whether log messages
   received by the journal daemon shall be forwarded to a traditional syslog

tasks/main.yml

@@ -3,6 +3,15 @@
 - name: Set platform/version specific variables
   include_tasks: tasks/set_vars.yml
 
+- name: Warn if journald_sync_interval is set in volatile mode
+  debug:
+    msg: >-
+      WARNING - journald_sync_interval should not be set when
+      journald_persistent: false
+  when:
+    - journald_sync_interval | int != 0
+    - not journald_persistent
+
 - name: Ensure required packages are installed
   package:
     name: "{{ __journald_packages }}"

templates/journald.conf.j2

@@ -16,6 +16,9 @@ SystemMaxFiles={{ journald_max_files }}
 SystemMaxFileSize={{ journald_max_file_size }}M
 {%   endif %}
 SplitMode={{ journald_per_user | bool | ternary("uid", "none") }}
+{% if journald_sync_interval | int != 0 %}
+SyncIntervalSec={{ journald_sync_interval }}m
+{% endif %}
 {# Volatile journal #}
 {% else %}
 Storage=volatile
@@ -31,8 +34,5 @@ RuntimeMaxFileSize={{ journald_max_file_size }}M
 {% endif %}
 {# end of storage specific settings #}
 {# settings below here apply to all storage types #}
-{% if journald_sync_interval | int != 0 %}
-SyncIntervalSec={{ journald_sync_interval }}m
-{% endif %}
 Compress={{ journald_compression | bool | ternary("yes", "no") }}
 ForwardToSyslog={{ journald_forward_to_syslog | bool | ternary("yes", "no") }}