[systemd-devel] [PATCH weston] doc/systemd: system service example

[Matt Hoosier]

On Dec 29, 2017 15:32, "Mantas Mikulėnas" <grawity at gmail.com> wrote:

On Fri, Dec 29, 2017 at 11:09 PM, Matt Hoosier <matt.hoosier at gmail.com>
wrote:

>
> The approach that you and Pekka most recently put on record here:
>
> * User=foo
> * PAMName=weston
>
> with a /etc/pam.d/weston that just does minimal stuff (enforce the
> account exists and then execute pam_systemd.so for the session phase)
> works well for me.
>
> One thing I can't figure out though: using PAMName= causes the service
> process's journal entries emitted by regular stdout and stderr not to
> be visible with 'journalctl -u weston.service' anymore. Only the
> messages coming internally from systemd ("Started Weston." and
> similar) show in that journal.
>
> I've tacked in StandardOutput=journal and StandardError=journal to
> compensate for the StandardInput=tty-fail. The messages do make it
> across to journald; you can view them with 'journalctl
> /usr/bin/weston'. But somehow they're not associated with the system
> unit weston.service anymore. Does using the PAMName= directive cause
> the stdout/stderr messages to be reassigned to a user-session unit or
> something?
>

No, it's done by pam_systemd specifically.

The main purpose of pam_systemd is to create a user session and move the
process to the session's own cgroup (from the weston.service cgroup). As a
result systemd no longer considers it as belonging to the weston.service
unit, but to session-c123.scope or such.)

(The same happens with all other interactive login types -- e.g. when you
log in at the console, you get moved out of getty at .service and into your
own cgroup.)

-- 
Mantas Mikulėnas


Okay, thanks. So that's just hardwired behavior that we should expect? I
tried looking around the source to pam_systemd a bit, but quickly lost
track of the way that the 'type', 'class', and other parameters to logind's
CreateSession() eventually interact with systemd recordkeeping.

-Matt
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