Re: gnome-session logging

[Simon McVittie <simon mcvittie collabora co uk>]

On 20/05/16 13:40, Sebastian Geiger (Lanoxx) wrote:
> 1. I said _most_ above, because there is still a tiny amout of output
> going to .xsession-errors

.xsession-errors is entirely a downstream thing, as far as I'm aware, so
you should talk to your distribution maintainers (in this case Ubuntu).
I think the relevant package is x11-common.

The display manager you are using (probably lightdm on Ubuntu, unless
you have deliberately installed a closer-to-upstream GNOME stack) is
also influential.

> I believe that
> gnome-session should be aware from which binary the output is coming
> when it sends it to syslog.

This was implemented in GNOME 3.20.

The way to do this is not actually sd_journal_send(), but creating a
sd_journal_stream_fd() per child process and passing it to the child
process as its stdout and stderr. That's what gnome-session 3.20 does;
semi-recent dbus-daemon does the same for D-Bus-activated services.

The "syslog tag" is the complete well-known bus name for D-Bus-activated
services or the .desktop filename for gnome-session-started
applications, for example here are some from my syslog:

May 20 13:54:22 archetype org.gnome.OnlineAccounts[2722]:
(goa-daemon:2829): GoaBackend-WARNING **: secret_password_lookup_sync()
returned NULL
May 20 13:57:29 archetype sparkleshare.desktop[2946]: (mono:2964):
GLib-CRITICAL **: Source ID 16283 was not found when attempting to remove it

(GOA is a D-Bus service, Sparkleshare is an XDG autostart application
started by gnome-session.)

> additionally the logs in the journal are
> filed under two different "tags", one is "gnome-session" and another is
> "gnome-session-binary".

Anything in the GNOME session that opens its own logging stream will get
a separate logging tag, too.

-- 
Simon McVittie
Collabora Ltd. <http://www.collabora.com/>