Allow a mounted repository to be injected into yum

Mounting a yum repository file at /var/run/secrets/overrides.repo will
allow any image based on this to use those repositories.

Author: smarterclayton

images/base/Dockerfile

@@ -1,19 +1,17 @@
 #
 # This is the base image from which all OpenShift Origin images inherit. Only packages
-# common to all downstream images should be here. Depends on Centos 7.2+
+# common to all downstream images should be here. Depends on Centos 7.2+.
+#
+# This image accepts a mounted secret at /var/run/secrets/overrides.repo that will be
+# used to access packages if specified.
 #
 # The standard name for this image is openshift/origin-base
 #
 FROM centos:centos7
 
-# Until nss-3.21.0-9.el7_2 and openssl-libs-1.0.1e-51.el7_2.5.x86_64 is
-# released in the base image we need to manually update this to workaround an
-# issue where some of the mirrors are using a certificate
-RUN yum update -y nss openssl-libs && \
-    yum clean all
-
 RUN INSTALL_PKGS="which git tar wget hostname sysvinit-tools util-linux bsdtar epel-release \
       socat ethtool device-mapper iptables tree findutils nmap-ncat e2fsprogs xfsprogs lsof" && \
+    ln -s /var/run/secrets/overrides.repo /etc/yum.repos.d/ && \
     yum install -y $INSTALL_PKGS && \
     rpm -V $INSTALL_PKGS && \
     yum clean all && \

images/openvswitch/Dockerfile

@@ -3,7 +3,7 @@
 #
 # The standard name for this image is openshift/openvswitch
 #
-FROM centos:centos7
+FROM openshift/origin-base
 
 COPY scripts/* /usr/local/bin/