autopkgtest-build-lxd failing with bionic

[Scott Kitterman]

On Tuesday, February 20, 2018 10:44:42 PM Martin Pitt wrote:
> Steve Langasek [2018-02-16 11:12 -0800]:
...
> > I think the network-online.target is the better thing to key on.
> 
> I still don't like that much, though:
>   -  there is no requirement that this actually gets "implemented" or even
>      started (it's a passive target)
> 
>   - it's supposed to be a SysV backwards compat shim for LSB's "network"
>     dependency, and not well-defined
> 
>   - These tools should also work with Debian containers, which in theory
> could also run sysvinit. This is also the reason why they still use
> `runlevel` instead of `systemctl is-system-running` or something similar.
> 
> All of these are just heuristics, though; you could have all sorts of cases
> where all of these break, like sharing the host's network namespace, having
> no default route but a route to the configured apt proxy, etc. Maybe the
> closest approximation to this would be to grab the archive URL from
> /etc/apt/sources.list and put it in a curl loop, but (1) neither wget nor
> curl are in minimal installs, and (2) at that point it could just as well
> be an apt-get retry loop.

So what's the right systemd way to ensure the network is up?  I continue to 
fight bugs in the postfix unit file both in Debian and Ubuntu over things 
happening before the network is up.  As far as I can determine from the 
documentation, network-online.target should work, but I agree it doesn't do so 
reliably.

Currently postfix at .service has:

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

If inet_interfaces has been set to a specific IP address (which is a 
legitimate use), then if postfix tries to start before that IP address is 
available errors ensue.

Scott K