gnome-session logging

["Sebastian Geiger (Lanoxx)" <lanoxx gmx net>]

Hi fellow Gnome Devs,

Since my most recent system upgrade (Ubuntu 16.04, ~gnome 3.18) I got 
systemd and I noticed that _most_ gnome-session logs now endup in the 
journal rather then in ~/.xsession-errors where it used to be stored 
before (Ubuntu 14.04, ~gnome 3.10).

I generally like the move to the journal because it makes it easier to 
track what is happening on the system and I need to look at less files. 
I do have some thoughts and questions about this tough. I would be happy 
to help implement these ideas but I would first like to hear what the 
gnome (and gnome-session devs in particular) think about my toughts.

1. I said _most_ above, because there is still a tiny amout of output 
going to .xsession-errors, additionally the logs in the journal are 
filed under two different "tags", one is "gnome-session" and another is 
"gnome-session-binary". So in total there are now three ways to figure 
out what is happening in a session:

 * ~/.xsession-errors
 * journalctl SYSLOG_IDENTIFIER=gnome-session
 * journalctl SYSLOG_IDENTIFIER=gnome-session-binary

Can we somehow improve this to a) provide a single access point through 
the journal (or syslog) to get all logs from gnome-session and b) to 
allow easier filtering of logs not directly from gnome-session (see my 
next point about that)?

2. When I look at the journal meta data, I find that all application 
generated output which is all logged under the "gnome-session" tag goes 
through syslog since all entries have the following meta data attached: 
"SYSLOG_IDENTIFIER" : "gnome-session". This means that the journal 
output is much less useful then it could be. I believe that 
gnome-session should be aware from which binary the output is coming 
when it sends it to syslog. So if gnome-session would use 
sd_journal_send and attach some meta data of the originating process 
then we could apply filters to get output only for specific 
applications. Unless there is something I am not aware of then there is 
currently no way to retrieve the log output for individual applications.

This would be particularly useful since many applications to not print 
their application name or pid and so we get log lines like the following:

May 20 08:51:36 earth gnome-session[1172]: ERROR

3. Finally I would like to suggest to add the ability to enable 
gnome-session debug output either through an environment variable or a 
dconf flag to complement the `--debug` option.

If any of this has previously been discussed or even solved in a later 
version (I am still running 3.18) then please give me a pointer to the 
mailing list archive or let me know of the result.

Cheers
Sebastian