Y[OpenAFS-devel] OpenAFS release team weekly meeting

[Peter Gille]

On 2018-01-17 09:06:09 +0000, Harald Barth <haba@kth.se> wrote:

> So what's going on here?

Answering your systemd questions at least.

>    * Every login starts a systemd --user process

No, it starts a systemd --user if one is not already started for the
user that just logged in. It will then close that process on the last
logout. So at any time there should be one systemd --user per $USER.

Also, I *think* it's configurable if you want it to start only on local
logins or also on ssh logins etc.

> (even root)?

I think this is configurable, but I'm not sure. By default yes at least.

> By whom?

pam-systemd notifies logind and they then collaborate on setting up the
user session (it also sets up cgroups etc). See man 8 pam_systemd.

If it fails for whatever reason it will time out after a fairly short
time and allow login anyway (at least according to my experience).

>      (obviously every login needs its systemd :-/)

To start user services that want to be started on login (mpd, mail
fetch, pulseaudio, various desktop environment processes, ...) it can be
practical, yes. Probably you don't want to have many services like this
triggered for root, though, but that's up to you as the root user to
decide.

>    * When logging out / ending that session (?) that systemd --user is
>    terminated with SIGRTMIN+24?

See first answer. It will close on the last end of a login session for
that user. This might also tear down other processes in the users
cgroup.

See the 'loginctl enable-linger $user' option, and KillUserProcesses= in
logind.conf(5).

> Harald.

Cheers,
Peter