library/roles/nginx/tasks/nginx.yml: cache_update only if needed.

nginx/tasks/nginx.yml

@@ -1,20 +1,20 @@
 ---
 - name: Install the Ubuntu PPA for nginx
-  apt_repository: repo='{{ nginx_ppa_repo }}'
+  apt_repository: repo='{{ nginx_ppa_repo }}' update_cache=yes
   when:
     - nginx_use_ppa
     - "'{{ ansible_distribution }}' == 'Ubuntu'"
   tags: [ 'nginx', 'nginx_ppa' ]
 
 - name: Install the nginx web server
-  apt: pkg={{ item }} state={{ nginx_package_state }} update_cache=yes
+  apt: pkg={{ item }} state={{ nginx_package_state }} update_cache=yes cache_valid_time=1800
   with_items:
     - nginx-full
   when: not nginx_use_ldap_pam_auth
   tags: nginx
 
 - name: Install the nginx web server if we need ldap auth via pam
-  apt: pkg={{ item }} state=installed
+  apt: pkg={{ item }} state={{ nginx_package_state }} update_cache=yes cache_valid_time=1800
   with_items: 
     - nginx-extras
   when: nginx_use_ldap_pam_auth