Comment 30 for bug 1519331
Revision history for this message
| Scott Kitterman (kitterman) wrote Re: [Bug 1519331] Re: Postfix cannot resolve DNS if network was unavailable when it was started, such as on a laptop | #30 |
On Monday, May 15, 2017 08:49:42 PM you wrote:
> On Mon, May 15, 2017 at 06:45:21PM -0000, Scott Kitterman wrote:
> > I'm getting close to uploading a fix for this to Debian, so you might wait
> > for that.
>
> It looks like you've implemented this using the network-
> approach, which as you mentioned might not DTRT for the localhost-only use
> case. Did you decide that this is negligible?
That was the advice I got from the Debian systemd maintainers (that the impact
would be negligible).
> For the case of a server which always has a network connection, this works
> fine. For the case of a standalone system with no configured network
> connection, it probably also works fine. But for the case of e.g. a laptop
> that sometimes has network and sometimes doesn't, if the system comes up
> without network, postfix will not start and you will not have local
> delivery. Is this the behavior you expect with your change?
I tested this and if you're using NetworkManager at least there's some magic
that happens which causes systemd to restart postfix once the network is
available. Part of the reason I was having so much trouble replicating
problems others were seeing was getting NM to quit 'helping' as the test
system I was using also has a desktop installed.
> Ultimately I want to SRU this into affected stable Ubuntu releases, so would
> want a regression-free change.
>
> I see you are also setting After=nss-
> here - which is about DNS resolution specifically - would it not suffice to
> have postfix declare this After=nss-
> to be sequenced before it?
According to the Debian systemd people, the systemd-resolved is superfluous.
It's nss-lookup.target that I wanted all along.
There's a very helpful (at least for me) discussion in the last few entries in
the Debian bug. Reviewing that would be better advice than I have for what's
safe/not as I cribbed from Michael Biebl's suggestions after just enough
research to be able to convince myself I wasn't cargo culting.
Scott K