wordpress: Replace aufs with overlayfs

wordpress/tasks/main.yml

 ---
 # file: wordpress/tasks/main.yml
 
-- name: ensure we have aufs tools
-  apt:
-    name:
-      - aufs-tools
-      - aufs-dkms
-    state: present
-    install_recommends: false
-  tags:
-    - wordpress
-    - webservices
-
 - name: ensure the wordpress package is installed
   apt:
     name: wordpress
@@ -57,6 +46,17 @@
     - wordpress
     - webservices
 
+- name: Create overlayfs workdir for {{ wordpress_name }}
+  file:
+    state: directory
+    mode: '0700'
+    owner: root
+    group: root
+    path: "{{ wordpress_web_root }}/{{ wordpress_name }}-workdir"
+  tags:
+    - wordpress
+    - webservices
+
 # yamllint disable-line rule:line-length
 - name: "ensure local folders without write permissions for {{ wordpress_name }} exist"
   file:
@@ -93,10 +93,10 @@
 - name: "ensure the directories for {{ wordpress_name }} are mounted above each other"
   mount:
     state: mounted
-    fstype: aufs
-    name: "{{ wordpress_web_root }}/{{ wordpress_name }}/"
+    fstype: overlay
+    path: "{{ wordpress_web_root }}/{{ wordpress_name }}"
     # yamllint disable-line rule:line-length
-    opts: "br={{ wordpress_web_root }}/{{ wordpress_name }}-files/:/usr/share/wordpress,udba=reval"
+    opts: "upperdir={{ wordpress_web_root }}/{{ wordpress_name }}-files/,lowerdir=/usr/share/wordpress,workdir={{ wordpress_web_root }}/{{ wordpress_name }}-workdir"
     src: none
   tags:
     - wordpress