I have been trying to create a Galera cluster with IPv6 networking. I know there's some other issues regarding this as well, I've probably read them.
There's at least a few problems:
wsrep_sst_common IPv6 address / port parsing is broken:
I went through the history of the script, and I think this commit is the one breaking it: https://github.com/MariaDB/server/commit/c22ab56f0d690feee471e173a3d95acb642cd6dc#diff-0b1123372bd9bf8a76dd8dd90aa3808d
It was working after this pull request was merged: https://github.com/MariaDB/server/pull/644
I tried with xtrabackup-v2 and mariabackup. The other problem is that mariabackup doesn't even use the variables parsed by the common script, so the IPv6 things are parsed there again and it's broken too.