@ssingh recently drew my attention to the fact the IPv6 addresses he added in Netbox for some recently reimaged LVS hosts had disappeared.
This was unfortunately my fault, as the addresses were auto-generated and I recently purged all of those from Netbox. Somewhere I did know LVS was using them but it didn't spring to mind at the time.
As a reminder we usually embed the IPv4 address in the host part of the v6 address, e.g:
eno12399np0 UP 10.192.16.140/22 2620:0:860:102:10:192:16:140/64 fe80::1623:f2ff:fe4d:cd60/64
This is statically set up in /etc/network/interfaces:
iface eno12399np0 inet static pre-up /sbin/ip token set ::10:192:16:140 dev eno12399np0 up ip addr add 2620:0:860:102:10:192:16:140/64 dev eno12399np0
But LVS vlan sub-interfaces are using auto generated addresses, there is no v6-specific config for them in the interfaces file:
vlan2019@enp152s0f0np0 UP 10.192.33.9/22 2620:0:860:103:262:bff:fecb:55d0/64 fe80::262:bff:fecb:55d0/64
I can see in T102099 that @BBlack seems to think it's possible to use manually configured addresses for the vlan interfaces instead. Alternatively we can change our puppetdb import script to once-again import auto-generated IPs, but I'm not sure it makes sense to have LVS as an exception to what we do elsewhere.