cache_valid_time to apt module calls
diff --git a/roles/common-prep/tasks/main.yml b/roles/common-prep/tasks/main.yml
index 1ea1ad9..409a179 100644
--- a/roles/common-prep/tasks/main.yml
+++ b/roles/common-prep/tasks/main.yml
@@ -19,7 +19,11 @@
     - wait for host
 
 - name: Install standard packages
-  apt:  pkg={{ item }} state=present
+  apt:
+    pkg={{ item }}
+    state=present
+    update_cache=yes
+    cache_valid_time=3600
   with_items:
    - tmux
    - vim
diff --git a/roles/compute-prep/tasks/main.yml b/roles/compute-prep/tasks/main.yml
index ac65bc8..9a29e01 100644
--- a/roles/compute-prep/tasks/main.yml
+++ b/roles/compute-prep/tasks/main.yml
@@ -5,6 +5,8 @@
   apt:
     name={{ item }}
     state=latest
+    update_cache=yes
+    cache_valid_time=3600
   with_items:
     - python-yaml
 
diff --git a/roles/dns-nsd/tasks/nsd-Debian.yml b/roles/dns-nsd/tasks/nsd-Debian.yml
index 776cbdc..ca31790 100644
--- a/roles/dns-nsd/tasks/nsd-Debian.yml
+++ b/roles/dns-nsd/tasks/nsd-Debian.yml
@@ -4,6 +4,8 @@
   apt:
     name={{ item }}
     state=present
+    update_cache=yes
+    cache_valid_time=3600
   with_items:
     - nsd
 
diff --git a/roles/dns-unbound/tasks/unbound-Debian.yml b/roles/dns-unbound/tasks/unbound-Debian.yml
index da0254f..f878858 100644
--- a/roles/dns-unbound/tasks/unbound-Debian.yml
+++ b/roles/dns-unbound/tasks/unbound-Debian.yml
@@ -4,6 +4,8 @@
   apt:
     name={{ item }}
     state=present
+    update_cache=yes
+    cache_valid_time=3600
   with_items:
     - unbound
 
diff --git a/roles/head-prep/tasks/main.yml b/roles/head-prep/tasks/main.yml
index 37c4b0b..5a51ebf 100644
--- a/roles/head-prep/tasks/main.yml
+++ b/roles/head-prep/tasks/main.yml
@@ -4,6 +4,8 @@
 - name:  Install prerequisites for using PPA repos
   apt:
     name={{ item }}
+    update_cache=yes
+    cache_valid_time=3600
   with_items:
     - python-pycurl
     - software-properties-common