toggle preserve_hostname for ubuntu18 server

roles/0-init/tasks/hostname.yml

@@ -1,3 +1,16 @@
+- name: Is ubuntu-18 server
+  stat:
+    path: /etc/cloud/cloud.cfg
+    register: U18_server
+
+- name: edit cloud.cfg yaml
+  lineinfile:
+    dest: /etc/cloud/cloud.cfg
+    regexp: '^preserve_hostname*'
+    line: 'preserve_hostname: true'
+    state: present
+  when: U18_server is defined and U18_server.stat.exists
+
 - name: Turn the crank for systemd (debuntu)
   shell: hostnamectl set-hostname "{{ iiab_hostname }}.{{ iiab_domain }}"
   when: is_debuntu