diff --git a/roles/mediawiki/defaults/main.yml b/roles/mediawiki/defaults/main.yml
index f650561f4..2f49d7548 100644
--- a/roles/mediawiki/defaults/main.yml
+++ b/roles/mediawiki/defaults/main.yml
@@ -29,4 +29,4 @@ mediawiki_abs_path: "{{ mediawiki_install_path }}/mediawiki-{{ mediawiki_version
 mediawiki_url: /wiki
 mediawiki_url2: /mediawiki
 mediawiki_full_url: "http://{{ iiab_hostname }}.{{ iiab_domain }}{{ mediawiki_url }}"    # http://box.lan/wiki
-mediawiki_symlink: w # can also be mwlink. NO slashes as they are suppplied as needed in the code
+mediawiki_symlink: w    # Can also be mwlink. NO slashes as they are supplied as needed in the code
diff --git a/roles/mediawiki/tasks/apache.yml b/roles/mediawiki/tasks/apache.yml
new file mode 100644
index 000000000..d7669f548
--- /dev/null
+++ b/roles/mediawiki/tasks/apache.yml
@@ -0,0 +1,12 @@
+- name: Enable http://box{{ mediawiki_url }} via Apache    # http://box/wiki
+  command: a2ensite mediawiki.conf
+  when: mediawiki_enabled | bool
+
+- name: Disable http://box{{ mediawiki_url }} via Apache    # http://box/wiki
+  command: a2dissite mediawiki.conf
+  when: not mediawiki_enabled
+
+- name: Restart '{{ apache_service }}' systemd service
+  systemd:
+    name: "{{ apache_service }}"    # apache2 or httpd, as set in /opt/iiab/iiab/vars/<OS>.yml
+    state: restarted
diff --git a/roles/mediawiki/tasks/enable.yml b/roles/mediawiki/tasks/enable.yml
deleted file mode 100644
index df0ed43cd..000000000
--- a/roles/mediawiki/tasks/enable.yml
+++ /dev/null
@@ -1,62 +0,0 @@
-# Apache
-
-- name: Enable http://box{{ mediawiki_url }} via Apache    # i.e. http://box/wiki
-  command: a2ensite mediawiki.conf
-  when: apache_install and mediawiki_enabled
-
-- name: Disable http://box{{ mediawiki_url }} via Apache
-  command: a2dissite mediawiki.conf
-  when: apache_install and not mediawiki_enabled
-
-- name: Restart Apache systemd service ({{ apache_service }})
-  systemd:
-    name: "{{ apache_service }}"    # apache2 or httpd, as set in /opt/iiab/iiab/vars/<OS>.yml
-    state: restarted
-  when: apache_enabled | bool
-
-# NGINX
-
-- name: Enable http://box{{ mediawiki_url }} & http://box{{ mediawiki_url2 }} via NGINX, by installing {{ nginx_conf_dir }}/mediawiki-nginx.conf from template
-  template:
-    src: mediawiki-nginx.conf.j2
-    dest: "{{ nginx_conf_dir }}/mediawiki-nginx.conf"
-  when: nginx_install and mediawiki_enabled
-
-- name: Disable http://box{{ mediawiki_url }} & http://box{{ mediawiki_url2 }} via NGINX, by removing {{ nginx_conf_dir }}/mediawiki-nginx.conf
-  file:
-    path: "{{ nginx_conf_dir }}/mediawiki-nginx.conf"
-    state: absent
-  when: nginx_install and not mediawiki_enabled
-
-- name: Restart 'nginx' systemd service
-  systemd:
-    name: nginx
-    state: restarted
-  when: nginx_enabled | bool
-
-
-- name: Add 'mediawiki' variable values to {{ iiab_ini_file }}
-  ini_file:
-    path: "{{ iiab_ini_file }}"
-    section: mediawiki
-    option: "{{ item.option }}"
-    value: "{{ item.value | string }}"
-  with_items:
-    - option: name
-      value: MediaWiki
-    - option: description
-      value: '"MediaWiki is a blog and web site management application, from the people who create Wikipedia."'
-    - option: mediawiki_src
-      value: "{{ mediawiki_src }}"
-    - option: mediawiki_abs_path
-      value: "{{ mediawiki_abs_path }}"
-    - option: mediawiki_db_name
-      value: "{{ mediawiki_db_name }}"
-    - option: mediawiki_db_user
-      value: "{{ mediawiki_db_user }}"
-    - option: mediawiki_url
-      value: "{{ mediawiki_url }}"
-    - option: mediawiki_full_url
-      value: "{{ mediawiki_full_url }}"
-    - option: mediawiki_enabled
-      value: "{{ mediawiki_enabled }}"
diff --git a/roles/mediawiki/tasks/install.yml b/roles/mediawiki/tasks/install.yml
index 3b8151a1b..a260c0e04 100644
--- a/roles/mediawiki/tasks/install.yml
+++ b/roles/mediawiki/tasks/install.yml
@@ -8,43 +8,43 @@
 - name: Download {{ mediawiki_download_base_url }}/{{ mediawiki_src }} to {{ downloads_dir }}
   get_url:
     url: "{{ mediawiki_download_base_url }}/{{ mediawiki_src }}"
-    dest: "{{ downloads_dir }}"
+    dest: "{{ downloads_dir }}"    # /opt/iiab/downloads
     timeout: "{{ download_timeout }}"
     #force: yes
     #backup: yes
   when: internet_available | bool
 
-- name: Unpack it to permanent location {{ mediawiki_abs_path }}
+- name: Unarchive (unpack) it to permanent location {{ mediawiki_abs_path }} ({{ apache_user }}:{{ apache_user }}, u+rw,g+r,o+r)
   unarchive:
     src: "{{ downloads_dir }}/{{ mediawiki_src }}"
-    dest: "{{ mediawiki_install_path }}"
+    dest: "{{ mediawiki_install_path }}"    # /library
     owner: "{{ apache_user }}"
     group: "{{ apache_user }}"
     mode: u+rw,g+r,o+r    # '0755' forced executable bits on files
     keep_newer: yes
 
-- name: Create symlink {{ doc_root }}/{{ mediawiki_symlink }} -> {{ mediawiki_abs_path }}
+- name: Symlink {{ doc_root }}/{{ mediawiki_symlink }} -> {{ mediawiki_abs_path }}
   file:
-    src: "{{ mediawiki_abs_path }}"
-    path: "{{ doc_root }}/{{ mediawiki_symlink }}"
+    src: "{{ mediawiki_abs_path }}"    # /library/mediawiki-1.XY.Z
+    path: "{{ doc_root }}/{{ mediawiki_symlink }}"    # /library/www/html/w
     state: link
 
 - name: Start MySQL systemd service ({{ mysql_service }}) so we can create db
   systemd:
-    state: started
     name: "{{ mysql_service }}"
+    state: started
 
 - name: Create MySQL database {{ mediawiki_db_name }}
   mysql_db:
-    name: "{{ mediawiki_db_name }}"
-    state: present
+    name: "{{ mediawiki_db_name }}"    # iiab_mediawiki
+    #state: present
 
 - name: Create MySQL database user {{ mediawiki_db_user }} with password, and permissions to above db
   mysql_user:
-    name: "{{ mediawiki_db_user }}"
+    name: "{{ mediawiki_db_user }}"    # iiab_mediawiki_user
     password: "{{ mediawiki_db_user_password }}"
     priv: "{{ mediawiki_db_name }}.*:ALL,GRANT"
-    state: present
+    #state: present
 
 - name: Configure MediaWiki, if {{ mediawiki_abs_path }}/LocalSettings.php doesn't exist
   shell: >
@@ -61,29 +61,29 @@
     "{{ mediawiki_site_name }}"
     "{{ mediawiki_admin_user }}"
   args:
-    chdir: "{{ mediawiki_abs_path }}"
+    chdir: "{{ mediawiki_abs_path }}"    # /library/mediawiki-1.XY.Z
     creates: "{{ mediawiki_abs_path }}/LocalSettings.php"
 
 - name: Configure wgArticlePath variable in {{ mediawiki_abs_path }}/LocalSettings.php
   lineinfile:
-    dest: "{{ mediawiki_abs_path }}/LocalSettings.php"
+    path: "{{ mediawiki_abs_path }}/LocalSettings.php"    # /library/mediawiki-1.XY.Z
     line: '$wgArticlePath = "/wiki/$1";'
 
 - name: Configure $wgUsePathInfo variable in {{ mediawiki_abs_path }}/LocalSettings.php
   lineinfile:
-    dest: "{{ mediawiki_abs_path }}/LocalSettings.php"
+    path: "{{ mediawiki_abs_path }}/LocalSettings.php"    # /library/mediawiki-1.XY.Z
     line: '$wgUsePathInfo = true;'
 
 - name: Configure $wgServer variable in {{ mediawiki_abs_path }}/LocalSettings.php
   lineinfile:
-    dest: "{{ mediawiki_abs_path }}/LocalSettings.php"
+    path: "{{ mediawiki_abs_path }}/LocalSettings.php"    # /library/mediawiki-1.XY.Z
     regexp: '^\$wgServer ='
     line: '$wgServer = "//" . $_SERVER["HTTP_HOST"];'
 
 - name: Install /etc/{{ apache_conf_dir }}/mediawiki.conf from template, for http://box{{ mediawiki_url }} via Apache
   template:
     src: mediawiki.conf.j2
-    dest: "/etc/{{ apache_conf_dir }}/mediawiki.conf"
+    dest: "/etc/{{ apache_conf_dir }}/mediawiki.conf"    # apache2/sites-available on debuntu
 
 
 # RECORD MediaWiki AS INSTALLED
@@ -94,6 +94,6 @@
 
 - name: "Add 'mediawiki_installed: True' to {{ iiab_state_file }}"
   lineinfile:
-    dest: "{{ iiab_state_file }}"    # /etc/iiab/iiab_state.yml
+    path: "{{ iiab_state_file }}"    # /etc/iiab/iiab_state.yml
     regexp: '^mediawiki_installed'
     line: 'mediawiki_installed: True'
diff --git a/roles/mediawiki/tasks/main.yml b/roles/mediawiki/tasks/main.yml
index df4bbcc74..10d15f273 100644
--- a/roles/mediawiki/tasks/main.yml
+++ b/roles/mediawiki/tasks/main.yml
@@ -1,7 +1,60 @@
-- name: Install MediaWiki {{ mediawiki_version }}
-  include_tasks: install.yml
-  when: mediawiki_install and not mediawiki_installed is defined
+# "How do i fail a task in Ansible if the variable contains a boolean value?
+# I want to perform input validation for Ansible playbooks"
+# https://stackoverflow.com/questions/46664127/how-do-i-fail-a-task-in-ansible-if-the-variable-contains-a-boolean-value-i-want/46667499#46667499
 
-- name: Enable MediaWiki
-  include_tasks: enable.yml
-  when: mediawiki_install or mediawiki_installed is defined
+# We assume 0-init/tasks/validate_vars.yml has DEFINITELY been run, so no need
+# to re-check whether vars are defined here.  As Ansible vars cannot be unset:
+# https://serverfault.com/questions/856729/how-to-destroy-delete-unset-a-variable-value-in-ansible
+
+- name: Assert that "mediawiki_install is sameas true" (boolean not string etc)
+  assert:
+    that: mediawiki_install is sameas true
+    fail_msg: "PLEASE SET 'mediawiki_install: True' e.g. IN: /etc/iiab/local_vars.yml"
+    quiet: yes
+
+- name: Assert that "mediawiki_enabled | type_debug == 'bool'" (boolean not string etc)
+  assert:
+    that: mediawiki_enabled | type_debug == 'bool'
+    fail_msg: "PLEASE GIVE VARIABLE 'mediawiki_enabled' A PROPER (UNQUOTED) ANSIBLE BOOLEAN VALUE e.g. IN: /etc/iiab/local_vars.yml"
+    quiet: yes
+
+
+- name: Install MediaWiki {{ mediawiki_version }} if 'mediawiki_installed' not defined, e.g. in {{ iiab_state_file }}    # /etc/iiab/iiab_state.yml
+  include_tasks: install.yml
+  when: mediawiki_installed is undefined
+
+
+- name: Enable/Disable/Restart Apache if primary
+  include_tasks: apache.yml
+  when: not nginx_enabled
+
+- name: Enable/Disable/Restart NGINX if primary
+  include_tasks: nginx.yml
+  when: nginx_enabled | bool
+
+
+- name: Add 'mediawiki' variable values to {{ iiab_ini_file }}
+  ini_file:
+    path: "{{ iiab_ini_file }}"    # /etc/iiab/iiab.ini
+    section: mediawiki
+    option: "{{ item.option }}"
+    value: "{{ item.value | string }}"
+  with_items:
+    - option: name
+      value: MediaWiki
+    - option: description
+      value: '"MediaWiki is a blog and web site management application, from the people who create Wikipedia."'
+    - option: mediawiki_src
+      value: "{{ mediawiki_src }}"
+    - option: mediawiki_abs_path
+      value: "{{ mediawiki_abs_path }}"
+    - option: mediawiki_db_name
+      value: "{{ mediawiki_db_name }}"
+    - option: mediawiki_db_user
+      value: "{{ mediawiki_db_user }}"
+    - option: mediawiki_url
+      value: "{{ mediawiki_url }}"
+    - option: mediawiki_full_url
+      value: "{{ mediawiki_full_url }}"
+    - option: mediawiki_enabled
+      value: "{{ mediawiki_enabled }}"
diff --git a/roles/mediawiki/tasks/nginx.yml b/roles/mediawiki/tasks/nginx.yml
new file mode 100644
index 000000000..5c4caee08
--- /dev/null
+++ b/roles/mediawiki/tasks/nginx.yml
@@ -0,0 +1,16 @@
+- name: Enable http://box{{ mediawiki_url }} & http://box{{ mediawiki_url2 }} via NGINX, by installing {{ nginx_conf_dir }}/mediawiki-nginx.conf from template    # http://box/wiki & http://box/mediawiki
+  template:
+    src: mediawiki-nginx.conf.j2
+    dest: "{{ nginx_conf_dir }}/mediawiki-nginx.conf"    # /etc/nginx.conf.d
+  when: mediawiki_enabled | bool
+
+- name: Disable http://box{{ mediawiki_url }} & http://box{{ mediawiki_url2 }} via NGINX, by removing {{ nginx_conf_dir }}/mediawiki-nginx.conf    # http://box/wiki & http://box/mediawiki
+  file:
+    path: "{{ nginx_conf_dir }}/mediawiki-nginx.conf"    # /etc/nginx.conf.d
+    state: absent
+  when: not mediawiki_enabled
+
+- name: Restart 'nginx' systemd service
+  systemd:
+    name: nginx
+    state: restarted