[CORD-1145]
Option to enable apt-cache, conform feature toggles

Change-Id: I560808f4bf292063f9a5d6826b247520e5df3a04
diff --git a/prep-headnode-playbook.yml b/prep-headnode-playbook.yml
index 759a3c3..b1877db 100644
--- a/prep-headnode-playbook.yml
+++ b/prep-headnode-playbook.yml
@@ -32,35 +32,33 @@
   hosts: head
   become: yes
   roles:
-    - { role: interface-config, when: not on_maas }
+    - { role: interface-config, when: not use_maas }
 
 - name: Networking and DNS server on head node
   hosts: head
   become: yes
   roles:
-    - { role: head-mgmtbr, when: not on_maas }
-    - { role: dns-unbound, when: not on_maas }
-    - { role: dns-nsd, when: not on_maas }
+    - { role: head-mgmtbr, when: not use_maas }
+    - { role: dns-unbound, when: not use_maas }
+    - { role: dns-nsd, when: not use_maas }
 
 # needs to be in another set of plays so that nsd/unbound restart handlers run
 - name: Configure DNS resolution, DHCP on head node
   hosts: head
   become: yes
   roles:
-    - { role: dns-configure, when: not on_maas }
-    - { role: dhcpd, when: not on_maas }
+    - { role: dns-configure, when: not use_maas }
+    - { role: dhcpd, when: not use_maas }
 
 - name: Install apt-cacher-ng
   hosts: head
   become: yes
   roles:
-    - apt-cacher-ng
+    - { role: apt-cacher-ng, when: use_apt_cache }
 
-- name: Install elasticstack, and apache proxy
+- name: Install apache proxy
   hosts: head
   become: yes
   roles:
-    - java-oracle
-    - elasticstack
     - apache-proxy