Overhaul local user management

Fix user deletion on removal/reassignment
Improve efficiency and cross platform support

tasks/users-preprocessing.yml

@@ -1,15 +1,39 @@
 ---
-- name: Pre-processing
-  tags: always
-  block:
-    - name: Load users
-      include_vars:
-        file: users.yml
-    - name: Reconcile user targets with host targets to get host users
-      set_fact:
-        local_users: "{{ local_users | default([]) + [item if item.targets | intersect(targets) else None] }}"
-      with_items: "{{ users }}"
-    - name: Get administrative users
-      set_fact:
-        local_admin_users: "{{ local_admin_users | default([]) + [item.name if item.admin else None] }}"
-      with_items: "{{ local_users | difference([None]) }}"
+- name: Load users variables
+  include_vars:
+    file: users.yml
+
+- name: Reconcile user targets with host targets to get host users
+  set_fact:
+    local_users: >-
+      {{
+      local_users | default([]) + ([item] if item.targets | intersect(targets) else [])
+      }}
+  loop: "{{ users }}"
+
+- name: Determine local user names
+  set_fact:
+    local_user_names: "{{ local_user_names | default([]) + [item.name] }}"
+  loop: "{{ local_users }}"
+
+- name: Determine administrative users
+  set_fact:
+    local_admin_users: >-
+      {{
+      local_admin_users | default([]) + ([item] if item.admin | default(False) else [])
+      }}
+  loop: "{{ local_users }}"
+
+- name: Determine existing users
+  shell: 'grep omni /etc/group | cut -d: -f4 | tr "," "\n"'
+  changed_when: false
+  register: local_existing_users
+
+- name: Determine removed users
+  set_fact:
+    local_removed_users: >-
+      {{
+      local_removed_users | default([]) +
+      ([item] if item not in local_user_names else [])
+      }}
+  loop: "{{ local_existing_users.stdout_lines }}"