Bug#854475: postfix: systemd needs postfix at .service to have "After=network.target"

[Bernhard Schmidt]

Am 08.05.2017 um 16:18 schrieb Michael Biebl:

Hi,

> I'm missing context here. Can you go into more detail please? What exactly is the question here? 

Sorry.

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=854475 is about
several issues with postfix being started before the network is up,
failing to bind specific IPs or copying an empty resolvconf managed
/etc/resolv.conf into its chroot on startup. This is happening since
postfix ships native systemd units.

Postfix ships

postfix.service
https://sources.debian.net/src/postfix/3.1.4-4/debian/postfix.service/
(oneshot, ExecStart=/bin/true, After=network.target

postfix at .service
https://sources.debian.net/src/postfix/3.1.4-4/debian/postfix%40.service/)
(forking, PartOf=postfix.service, NO After=network.target)

Additionally a snipped in postinst drops an override in /etc in the
standard case of having systemd-resolved installed (not necessarily
used) and the configuration being a somehow managed standard
configuration. It adds additional After= dependencies for
postfix.service on network-online.target and systemd-resolved.service

https://sources.debian.net/src/postfix/3.1.4-4/debian/postfix.postinst/#L650
https://sources.debian.net/src/postfix/3.1.4-4/debian/postfix.postinst/#L185

It also ships a generator that directly links postfix@ instances into
the WANTDIR

postfix-instance-generator
https://sources.debian.net/src/postfix/3.1.4-4/debian/postfix-instance-generator/


Scott's question was why the After=network.target (and the additional
ordering statements added by the override) of postfix.service isn't
enough to ensure proper ordering on startup. If I understand this
correctly the generator will independently start the postfix at .service
instances. The PartOf=postfix.service does not affect ordering at all.


So for a proper fix the additional After= tweaks need to be added to
postfix at .service, not just postfix.service

Bernhard