Re: Server start with systemd and configured with IP address

PG Doc comments form <noreply(at)postgresql(dot)org> writes:
> My suggestion is add to the documentation in the segment that shows the
> systemd entry inside the [Unit] segment the line
> After=network-online.target

> I saw in several sites that most people recommends using
> After=network.target

> but this will fail if the server is configured to listen on a specific IP
> address instead of just localhost or 127.0.0.1

Yeah, I have also found with other daemons that if you use specific
IP addresses in the configuration, you need network-online.target.
Some references suggest that you *also* need to say
Wants=network-online.target [1].

It might be that network.target is sufficient if you just bind to
"*", but considering that we're not mentioning that either right
now, I don't see a need to discuss the difference.

(Down the road, maybe we should consider using IP_FREEBIND on
Linux, as suggested at [1] ... although that hobbles error
detection, so I'm not really sold that it's such a great idea.)

regards, tom lane

[1] https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget/