Conntrack missing, or how to install packages via ignition?

Hello,

I successfully managed to install Kubernetes on F coreos 31.20200420.3.0 with containerd as runtime. But during the run of “kubeadm init” I got an error saying that conntrack was missing (k8s 1.18 needs this, apparently).

Installing it via rpm-ostree is possible and easy: “rpm-ostree install conntrack”, but requires a reboot. Is there a possibility to add the package via ignition? Is it at all possible to add rpm-ostree packages via ignition, e.g. by specifying a modified treefile.json?
Otherwise I think it would make sense to add the package in the distribution, as certainly everybody who installs k8s will need it…

I think you are effectively reporting a duplicate of https://github.com/coreos/fedora-coreos-tracker/issues/404, which is in turn still blocked by https://bugzilla.redhat.com/show_bug.cgi?id=1814190.