The OVNKubernetes projects has a super complex [bash script](https://github.com/openshift/machine-config-operator/blob/master/templates/common/_base/files/configure-ovs-network.yaml) to setup the `brext` ovs bridge, at least some of those parts can be done with nmpolicy.
The OVNKubernetes projects has a super complex bash script to setup the
brextovs bridge, at least some of those parts can be done with nmpolicy.