[lttng-dev] one sessiond for multiuser system

[Jérémie Galarneau]

On Fri, Aug 9, 2013 at 4:01 AM, Stanislav Vovk
<stanislav.vovk at ericsson.com> wrote:
> Hi,
>
> Have a few questions regarding lttng configuration in a multi user system.
>
> In my system there are two users, root and Bob. I am starting sessiond at boot as root user. And instrumented programs are started as either root or Bob. I am logged in to the system and controlling lttng as root user.
>
> - When executing "lttng list -u" I see events registered by programs started as root. I don't see events from programs started as Bob. Why? Did I forget something?
>
> - Now I switch user to Bob in the shell. Executing "lttng list -u" does not give any output at all, instead a new sessiond is started. How can I have one sessiond for the whole system?

Hi Stanislav,

A non-privileged user can only interact with a root session daemon if
he is part of the "tracing" group. Is it the case for "Bob" in this
example?

Reproducing your scenario here with "Bob" being part of the tracing group:
- Root can list its own sessions as well as Bob's
- Bob's user space events can also be seen by root
- Bob can't see the sessions created by root.

Regards,
Jérémie

>
> Cheers,
> Stanislav
>
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-- 
Jérémie Galarneau
EfficiOS Inc.
http://www.efficios.com