We do this all the time, for example, there's a backend network we use for building boxes and we like using it as a backdoor for ssh as well, but we don't want wicked applying a route to the network interface. So we set up DHCP for the network and add the following block to the

90_custom.yaml

:

- path: /etc/sysconfig/network/ifcfg-eno1
              permissions: 384   
              owner: 0  
              group: 0  
              content: |   
                STARTMODE='auto'   
                BOOTPROTO='dhcp'   
                DHCLIENT_SET_DEFAULT_ROUTE='no'   
              encoding: ""
              ownerstring: ""

That drops the cfg into etc on boot and wicked activates during the systemd startup.

If you need to do more than that, there's other yaml you'll need as a hack and you'll have to add

rd.cos.rwdebug

to the kernel line in the grub boot to trigger the overlays getting applied (aka not applied) correctly.

ProTip: Leave

/var

immutable to avoid screwing up the

var/lib/harvester/defaultdisk

path at boot. If you don't, just be sure to umount and delete the directory it creates.