roles/nextcloud: Install prereq MySQL / MariaDB

roles/nextcloud/tasks/install.yml

@@ -1,3 +1,18 @@
+- name: "Set 'mysql_install: True' and 'mysql_enabled: True'"
+  set_fact:
+    mysql_install: True
+    mysql_enabled: True
+
+- name: MYSQL - run 'mysql' role (attempt to install & enable MySQL / MariaDB)
+  include_role:
+    name: mysql
+
+- name: FAIL (STOP THE INSTALL) IF 'mysql_installed is undefined'
+  fail:
+    msg: "Nextcloud install cannot proceed, as MySQL / MariaDB is not installed."
+  when: mysql_installed is undefined
+
+
 - name: Record (initial) disk space used
   shell: df -B1 --output=used / | tail -1
   register: df1