Create a minimal image based on CentOS

Use of this element will require ‘yum’ and ‘yum-utils’ to be installed on Ubuntu and Debian. Nothing additional is needed on Fedora or CentOS.

By default this builds CentOS 7 images. Set DIB_RELEASE to 7, 8 or 8-stream to explicitly select the release.

For CentOS 7, by default, DIB_YUM_MINIMAL_CREATE_INTERFACES is set to enable the creation of /etc/sysconfig/network-scripts/ifcfg-eth[0|1] scripts to enable DHCP on the eth0 & eth1 interfaces. If you do not have these interfaces, or if you are using something else to setup the network such as cloud-init, glean or network-manager, you would want to set this to 0. For CentOS 8 and CentOS 8 Stream, this is set to 0 by default as the system uses NetworkManager by default.