This adds an additional network to the traefik container with a public IPv6 network attached to it. Docker will automatically assign a free address to the traefik container from the IPv6 subnet
Internally traefik will still forward traefik over an IPv4 network
Note that, because docker does not do any NAT for IPv6 or proxying, and this uses publically routable IPv6 addresses, traffic directly reaches the containers, unless you block it with a firewall. For 80/443, you actually want this to happen though.
In some circumstances, I noticed that the IPv6 subnets assigned to docker were net externally reachable. This is because the external gateway is trying to discover the destination with NPD, and nothing is responding. Linux does not do that by default.
There is a sysctl setting called sys.net.ipv6.conf.all.proxy_npd
which should enable this, but for me this still
didn't was enough. Installing a service called npd6 and setting the assigned subnet in the confiugration finally
made it work.