To enable IPv6 for BGP, enable IPv6 on global level using this guide and configure IPv4 BGP integration.
First of all, you need to enable BGP action for IPv6 traffic:
sudo fcli set main gobgp_ipv6 enable
To announce attacked host (/128) use this option:
sudo fcli set main gobgp_announce_host_ipv6 enable
And configure community numbers for host and subnet (it’s not implemented yet) blocks:
sudo fcli set main gobgp_community_host_ipv6 65001:666 sudo fcli set main gobgp_community_subnet_ipv6 65001:667
Finally, configure next hop to required value:
sudo fcli set main gobgp_next_hop_ipv6 100::1
Also, you need to enable IPv6 NLRI for particular peer:
sudo fcli set bgp peer_name ipv6_unicast enable sudo flci commit
You will need to enable ipv6_flowspec if you use Flow Spec too.
Before moving this setup to production, try blocking any test host manually and check that all announces propagate correctly.