C7knl is a kernel and associated files which was used with SystemImager to install Centos 7 images on compute nodes. It is derived in part from BOEL, which is normally used with SystemImager in this role.
SystemImager is software that makes the installation of Linux to masses of similar machines relatively easy. It makes software distribution, configuration, and operating system updates easy, and can also be used for content distribution.
SystemInstaller is a tool to install a system with any Linux distribution. It works hand-in-hand with SystemImager and SystemConfigurator to build a cluster.