[systemd-devel] journal: how to query journal to see ALL output of given unit?

[Zbigniew Jędrzejewski-Szmek]

On Tue, Jan 07, 2014 at 11:21:41PM +0200, Mantas Mikulėnas wrote:
> On Tue, Jan 7, 2014 at 11:19 PM, Warpme <warpme at o2.pl> wrote:
> > On 06/01/14 21:52, Zbigniew Jędrzejewski-Szmek wrote:
> >>
> >> journalctl -o verbose for mysqld-check.sh
> >
> > Zbyszku,
> >
> > Here is output for 'journalctl SYSLOG_IDENTIFIER=mysqld-check.sh -o verbose'
> >
> > Sat 2014-01-04 23:32:07.364159 CET
> > [s=bd641dc956b04278a26115fa814b910a;i=4365;b=1fad31caaf1e48348c9d4403b7d68ff6;m=2689289;t=4ef2c98c3163f;x=dc153004a
> >     _TRANSPORT=stdout
> >     PRIORITY=6
> >     SYSLOG_FACILITY=3
> >     _UID=0
> >     _GID=0
> >     _MACHINE_ID=beb0f0a1c2c303b17213bb8d4a87a3a6
> >     _HOSTNAME=mythtv
> >     _CAP_EFFECTIVE=1fffffffff
> >     _BOOT_ID=1fad31caaf1e48348c9d4403b7d68ff6
> >     SYSLOG_IDENTIFIER=mysqld-check.sh
> >     MESSAGE=--> mysqld: No need to check MythTV DB. Stop was clean...
> >     _PID=807
> >     _COMM=mysqld-check.sh
> >
> > And here is exemplary output for mysqld:
> >
> > Mon 2014-01-06 16:24:36.037183 CET
> > [s=6d5ef6e5ef9e413fbcb7fca114dd8465;i=43cb;b=5bbb0bb34be64b14886ed38600badb66;m=41e23ff;t=4ef4edb81a63f;x=b9e5fbfb9
> >     _TRANSPORT=stdout
> >     PRIORITY=6
> >     SYSLOG_FACILITY=3
> >     _UID=0
> >     _GID=0
> >     _SYSTEMD_SLICE=system.slice
> >     _MACHINE_ID=beb0f0a1c2c303b17213bb8d4a87a3a6
> >     _HOSTNAME=mythtv
> >     _CAP_EFFECTIVE=1fffffffff
> >     SYSLOG_IDENTIFIER=su
> >     _COMM=su
> >     _EXE=/bin/su
> >     _CMDLINE=/bin/su mysql -c /usr/bin/mysqld
> > --defaults-file=/etc/mysql/my.cnf --datadir=/var/lib/mysql
> > --socket=/var/run/mysqld/mysqld.sock
> >     _SYSTEMD_CGROUP=/system.slice/mysqld.service
> >     _SYSTEMD_UNIT=mysqld.service
> >     _BOOT_ID=5bbb0bb34be64b14886ed38600badb66
> >     _PID=1478
> >     MESSAGE=Version: '5.5.24'  socket: '/var/run/mysqld/mysqld.sock'  port:
> > 3306  Source distribution
> 
> It could be that the script exits before journald has a chance to read
> its cgroup information.
That's what I'd guess too. Does is get "fixed" if you insert 'sleep 1' in
mysql-check.sh before it exits?

This seems likely because the output suggests that the script is short-lived.
> >     SYSLOG_IDENTIFIER=mysqld-check.sh
> >     MESSAGE=--> mysqld: No need to check MythTV DB. Stop was clean...

> – it's a known limitation which AFAIK needs
> minor kernel changes (or maybe kdbus?)
The addition of additional information in the style of SO_CREDENTIALS
for normal sockets was rejected by Eric Biederman with "I don't like you"
as an explanation. So going through kdbus is the next option.

Zbyszek