add backup of previous index

tasks/configure_custom_theme.yml

@@ -34,6 +34,13 @@
     path: /usr/src/nagio4_theme/index.php
   register: index_php
 
+- name: Backup previous index.php
+  copy:
+    remote_src: true
+    src: /usr/share/nagios4/htdocs/index.php
+    dest: /usr/share/nagios4/htdocs/index_previous.php
+  when: index_php.stat.exists
+
 - name: Copy custom index.php
   copy:
     remote_src: true