dracut-network binary package in Ubuntu Bionic s390x

 Unlike existing initramfs's, this is an attempt at having as little as
 possible hard-coded into the initramfs as possible. The initramfs has
 (basically) one purpose in life -- getting the rootfs mounted so that
 we can transition to the real rootfs. This is all driven off of
 device availability. Therefore, instead of scripts hard-coded to do
 various things, we depend on udev to create device nodes for us and
 then when we have the rootfs's device node, we mount and carry on.
 Having the root on MD, LVM2, LUKS is supported as well as NFS, iSCSI,
 NBD and FCOE with dracut-network.

Source package