-SSH_OPTIONS="-o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o LogLevel=Verbose -o PasswordAuthentication=no -o ConnectionAttempts=32"
-
-read -a Controller_hosts_a <<< $CONTROLLER_HOSTS
-read -a Compute_hosts_a <<< $COMPUTE_HOSTS
-read -a BlockStorage_hosts_a <<< $BLOCKSTORAGE_HOSTS
-read -a ObjectStorage_hosts_a <<< $OBJECTSTORAGE_HOSTS
-read -a CephStorage_hosts_a <<< $CEPHSTORAGE_HOSTS
+SSH_OPTIONS="-tt -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o LogLevel=Verbose -o PasswordAuthentication=no -o ConnectionAttempts=32"
+OVERCLOUD_ROLES=${OVERCLOUD_ROLES:-"Controller Compute BlockStorage ObjectStorage CephStorage"}
+
+# Set the _hosts vars for the default roles based on the old var names that
+# were all caps for backwards compatibility.
+Controller_hosts=${Controller_hosts:-"$CONTROLLER_HOSTS"}
+Compute_hosts=${Compute_hosts:-"$COMPUTE_HOSTS"}
+BlockStorage_hosts=${BlockStorage_hosts:-"$BLOCKSTORAGE_HOSTS"}
+ObjectStorage_hosts=${ObjectStorage_hosts:-"$OBJECTSTORAGE_HOSTS"}
+CephStorage_hosts=${CephStorage_hosts:-"$CEPHSTORAGE_HOSTS"}
+
+# Set the _hosts_a vars for each role defined
+for role in $OVERCLOUD_ROLES; do
+ eval hosts=\${${role}_hosts}
+ read -a ${role}_hosts_a <<< $hosts
+done