We have a few new hosts installed for x2 (T269324) and they all got a ipv6:
root@cumin1001:~# host db2142.codfw.wmnet db2142.codfw.wmnet has address 10.192.0.14 db2142.codfw.wmnet has IPv6 address 2620:0:860:101:10:192:0:14
Those hosts are having connection issues, as grants aren't ready for those.
# mysql.py -hdb2142 ERROR 1045 (28000): Access denied for user 'root'@'2620:0:861:103:10:64:32:25' (using password: YES)
These hosts aren't in production, but this is going to be an issue if we need to upgrade all the grants on all the hosts as soon as they start getting ipv6s.
Right now our grants (for mw general) are:
wikiadmin 10.64.% wikiuser 10.64.% wikiadmin 10.192.% wikiuser 10.192.%
But we also have plenty of other grants (like root, watchdog etc).
Until we have a proper management system, we might need to disable ipv6 on DB hosts (and their DNS)