[Kea-users] HA with kea-dhcp4: beginner questions

[Stefan G. Weichinger]

Greetings, I subscribed to this list 5 minutes ago because this morning 
we had a event I can't yet fully explain.

A few weeks ago I set up a kea-HA-cluster of 2 Debian-11 nodes using the 
2.3.2 packages from the isc-repos.

I run kea-dhcp4 only on the 2 nodes, no DHCPv6 or DDNS. For sure I 
configured the kea-ctrl-agents as well and installed stork-server plus 
agents (server only on one node ...).

We only use memfile, no database for DHCP.

Things looked good so far. 4 subnets in several VLANs, logs quiet.

the 2 nodes are named adc1 and adc2: they are also Samba Domain 
Controllers. Yesterday I upgraded samba on adc2 and had to 
uninstall/upgrade samba-related packages.

adc2 is the primary kea-node.

I didn't look at kea yesterday, and no outage was noticed or reported.

-

This morning I was alarmed because no DHCP leases were served. The local 
admin considered adc2 the reason and wanted to unplug it .. but 
unplugged adc1 instead.

Still no leases ... after maybe 9 minutes he reconnected adc1 and 
unplugged adc2: after that (= adc2 gone) leases worked again.

I browsed the logs etc (could it be that kea logs in UTC and not in my 
local timezone?). Everything quiet in there until the boxes were 
unplugged, so no error visible until that manual intervention.

My assumption:

the samba-installation might have removed or replaced some package kea 
depends on. I don't know what ...

so maybe kea on adc2 was already not working OK anymore yesterday 
evening and in the night ... but that wasn't noticed because the leases 
were still active (?)

and today adc2 still was reachable in terms of HA but not fully working 
anymore (the cluster stayed with adc2 as primary ...)

and the mistake with the unplugging lead to even more delay in getting a 
stable HA state again.

-

Sorry for the long description, maybe I hit a beginner issue here.

For sure I am happy to show configs and logs if helpful. I tried to stay 
along the docs for sure, and I don't see any errors really.

adc2 has been rebooted this morning and currently both DHCP-cluster and 
samba-DCs are working fine.

Thanks for any feedback, Stefan