[systemd-devel] requiring all template instances in a service

[Andrei Borzenkov]

В Thu, 26 Feb 2015 11:56:45 -0500
Benjamin Rose <benrose at math.princeton.edu> пишет:

> So given the distro unit file for teamd on RHEL7:
> 
> [Unit]
> Description=Team Daemon for device %I
> [Service]
> BusName=org.libteam.teamd.%i
> ExecStart=/usr/bin/teamd -U -D -t %i -f /run/teamd/%i.conf
> 
> Should I just make something like this...?
> 
> /etc/systemd/system/teamd at .service.d/require_network.conf:
> Before=network.service
> 
> Perhaps I am misunderstanding the relationship between network.service 
> and network.target?


network.target is common synchronization point. Services that need to
be started after network can order itself after it. Services that
implement network should order itself before it. This frees individual
consumers of dependencies on actual implementation.

>                     Really, network.service is what starts the teamd 
> processes.

This is network.service in your case. In other cases it could be
NetworkManager.service, or systemd-networkd.service or wicked.service. 

>           The question is how to make sure systemd knows to stop 
> pacemaker before stopping all of the teamd processes. 

By ordering pacemaker after teamd services. But if you want to be
independent of actual implementation, pacemaker should come After
network.target and teamd (or whatever) should come Before
network.target. If teamd itself is instantiated template, just include
Before in template and every instance will automatically inherit it.

>                                                      I would have 
> thought since network.service generated the teamd instances, it would 
> have known to keep them alive until all services requiring network were 
> finished.
> 

I'm not sure what "it" in the above sentence refers to. If you mean
"systemd" then it only respects After and Before relations. This is
even documented :)

> Thanks,
> Ben
> 
> On 02/25/2015 10:38 PM, Andrei Borzenkov wrote:
> > В Wed, 25 Feb 2015 18:42:47 -0500
> > Benjamin Rose <benrose at math.princeton.edu> пишет:
> >
> >> Hello all,
> >>
> >> I hope this is the right place for this inquiry. I was noticing
> >> extremely slow reboot times on three of my hosts running
> >> corosync/pacemaker for shared storage. I enabled the systemd debug logs,
> >> and found that pacemaker was attempting to communicate with it's peers
> >> to notify of the shutdown, and failed to do so as networking was not
> >> functioning. This was odd because networking was fine during normal
> >> operation and the distribution's unit file has the proper "Requires" for
> >> networking. Eventually it hit the distro "TimeoutStopSec=30m" and forced
> >> the reboot, hence the slow reboot times.
> >>
> >> In the debug logs, I found that it was all because I am using teamd
> >> (partially related - through ifcfg files using network.service), and
> >> teamd was being killed long before pacemaker got the chance to send its
> >> closing messages. So, I fixed the problem in my implementation with this
> >> little bit:
> >>
> >> [root at myhost ~]# cat
> >> /etc/systemd/system/pacemaker.service.d/require_teamd.conf
> >> [Unit]
> >> After=teamd at team_pub.service
> >> After=teamd at team_priv.service
> >> Requires=teamd at team_pub.service
> >> Requires=teamd at team_priv.service
> >>
> >> But, soon I will be changing a lot about my networking. I'll be using
> >> puppet to deploy a few more teams and bridges on this host. So, my
> >> question comes down to - is there a way to accomplish something like this:
> >>
> >> Requires=teamd@*.service
> >> After=teamd@*.service
> >>
> >> to include all running instances? I know this makes no sense in an
> >> xinetd-type situation on bootup, when instances will be created
> >> on-demand, but it does make perfect sense on a shutdown or reboot to
> >> want to wait for all instances of a certain type to complete their work
> >> before proceeding.
> >>
> > Services that implement networking are expected to order itself before
> > network.target on startup and hence after network.target on shutdown,
> > so that it should be sufficient to just have
> >
> > After=network.target
> >
> 
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