removing forced packages update. added ENV REFRESHED_AT to control im…

…age cache

Dockerfile

@@ -1,4 +1,5 @@
 FROM centos:centos7
+ENV REFRESHED_AT 2016-08-09
 
 # Define args and set a default value
 ARG maintainer=tier
@@ -17,7 +18,7 @@ LABEL Build docker build --rm --tag $maintainer/$imagename .
 # Install base deps
 RUN yum -y install --setopt=tsflags=nodocs epel-release && \
     yum -y install net-tools wget curl tar unzip mlocate logrotate strace telnet man unzip vim wget rsyslog cron && \
-    yum -y update && yum clean all
+    yum clean all
 
 # Install Trusted Certificates
 RUN update-ca-trust force-enable