add default variables

defaults/main.yml

@@ -12,3 +12,13 @@ interface_file: '
 interface_clean: True
 interface_mtu: 1442
 
+interface_mac:
+interface_default_gateway:
+interface_routes: []
+# - gateway:
+#   network:
+#   mask:
+
+interface_required_variables:
+    interface_mac: '{{ interface_mac }}'
+

tasks/main.yml

+
 - name: check existence of required variables
   fail:
-      msg: interface_mac is not defined
-  when: not interface_mac
+      msg: required variable '{{ item.key }}' is undefined
+  when: item.value is undefined or not item.value
+  loop: '{{ interface_required_variables }}'
 
 - set_fact:
       interface_device: '{%- from "roles/common/templates/network.j2" import mac_to_interface with context -%}
@@ -11,3 +13,4 @@
   when: interface_clean is defined and interface_clean
 
 - include: interface.yml
+