Fix the packages installation task.

iptables/defaults/main.yml

@@ -1,4 +1,8 @@
 ---
+iptables_deb_pkgs:
+  - iptables
+  - iptables-persistent
+
 #
 # Reference only. Check the iptables-rules.v4.j2 for the list of accepted variables
 #

iptables/tasks/main.yml

@@ -1,10 +1,7 @@
 ---
 - block:
   - name: Install the needed iptables packages
-    apt: pkg={{ item }} state=present
-    with_items:
-      - iptables
-      - iptables-persistent
+    apt: pkg={{ iptables_deb_pkgs }} state=present cache_valid_time=1800
 
   - name: Create the /etc/iptables directory when needed
     file: dest=/etc/iptables state=directory owner=root group=root mode=0755