requiring the network to be configured for a service (KEA DHCPD)

[Thorsten Glaser]

Hi,

we’re currently trying to debug/fix a set of interconnected issues
in the KEA DHCP/DHCP6 server which involve systemd as well:


One is that, when the services start, the network is not precisely
up and working yet, and so it logs…

Apr 21 09:29:11 debian kea-dhcp4[1634]: WARN  DHCPSRV_NO_SOCKETS_OPEN no interf[…]

… but starts successfully despite not working.

It already has…

Wants=network-online.target
After=network-online.target

… which a coworker who knows systemd better says ought to suffice,
but it turns out (in his debugging experiments) that network-online
can still have the network interfaces in DOWN state.

Restarting the service once the system has booted makes it work.

I think this is something we need to address by a code change (abort
instead of continuing when this particular error occurs) plus a change
in the unit to let systemd attempt to restart it… can it do this with
a backoff (i.e. first after 30s, then after a minute, then after 3min,
etc.)?


The other is that KEA DHCPD (both v4 and v6) must be restarted when
the network is restarted. Am I correct that keeping the After= from
above and changing the Wants= into BindsTo=network-online.target will
do that?

(KEA maintainers, is this also needed for the third (DDNS) service?)


Thanks in advance,
//Thorsten
-- 
Thorsten Glaser
Linux / Unix Developer
Tel.: +49 160 91168501
E-Mail: tglaser at b1-systems.de

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