This configures routing (iptables) and HA (keepalived) on router nodes
One of the nodes gets IPv4 and IPv6 of via keepalived. Each node's IPTables is configured for simple firewalling, have a look at defaults/main.yml for defaults.
If you remove the last DROP rule in FORWARDING and set it's policy to accept you can quickly use this machine as a gateway to the internet (if your IPMI needs this for some update or something).