Add support for enabling elrepo-kernel repository

Author: cityofships

elements/elrepo/README.rst

@@ -3,7 +3,10 @@ ELRepo
 ======
 
 Enables ELRepo, a community based repository for Enterprise Linux Packages with a focus
-on drivers for hardware such as network interface cards.
+on drivers for hardware such as network interface cards. RHEL/CentOS versions pior to 8
+are not supported.
 
 * ``DIB_ELREPO_PKGLIST`` A list of packages to install from ELRepo.
   Default is none.
+* ``DIB_ELREPO_KERNEL`` Whether elrepo-kernel repository containing kernel-ml packages
+  should be enabled (1) or disabled. Default is disabled (0).

elements/elrepo/pre-install.d/01-elrepo

@@ -4,6 +4,14 @@ case "$DISTRO_NAME" in
     centos* | rhel*)
 	rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
 	dnf install -y https://www.elrepo.org/elrepo-release-8.el8.elrepo.noarch.rpm
+
+	if [ ${DIB_ELREPO_KERNEL:-0} -eq 1 ]; then
+
+		rpm -q dnf-plugins-core || dnf install -y dnf-plugins-core
+		dnf config-manager --set-enabled "elrepo-kernel"
+
+	fi
+
 	;;
     *)
 	echo "Distro \"$DISTRO_NAME\" is not supported"