[lttng-dev] one sessiond for multiuser system

[Jérémie Galarneau]

On Mon, Aug 12, 2013 at 8:31 AM, Stanislav Vovk
<stanislav.vovk at ericsson.com> wrote:
> Hi,
>
> No, "Bob" did not belong to group "tracing"!
>
> I created group "tracing", added Bob to it(as secondary group, "users" is primary) and could successfully see all events registered by program run as Bob. Thanks for that!

Glad I could help!

> One problem though, when I took a snapshot with "lttng snapshot record" consumerd crashed! See below for debug output from sessiond. Seems like a bug to me, something to add to the bugtracker?

Yes, please file a new bug entry against the lttng-tools project and
join any relevant logs, stack traces or core dumps you may have.
Also, include reproduction steps if you can you get it to crash reliably.

Regards,
Jérémie

>
> Cheers,
> Stanislav
>
> DEBUG1 [2056/2061]: Sending metadata request to sessiond, session id 0, per-pid 6 (in lttng_ustconsumer_request_metadata() at ust-consumer.c:1867)
> DEBUG1 [1855/2057]: Metadata request received for session 0, key 8 (in ust_consumer_metadata_request() at ust-consumer.c:455)
> DEBUG3 [1855/2057]: Buffer registry per UID find id: 0, ABI: 32, uid: 0 (in buffer_reg_uid_find() at buffer-registry.c:195)
> DEBUG3 [1855/2057]: No metadata to push for metadata key 4 (in ust_app_push_metadata() at ust-app.c:441)
> DEBUG1 [1855/2057]: No metadata to push (in ust_app_push_metadata() at ust-app.c:444)
> DEBUG2 [1855/2057]: Consumer push metadata to consumer socket 33 (in consumer_push_metadata() at consumer.c:1175)
> lttng-consumerd: ust-consumer.c:1907: lttng_ustconsumer_request_metadata: Assertion `key == channel->key' failed.
> DEBUG1 [1855/1858]: Fail to receive status reply on sock 32 (in consumer_recv_status_reply() at consumer.c:58)
> DEBUG1 [1855/1858]: Sending response (size: 16, retcode: Snapshot record failed) (in thread_manage_clients() at main.c:3765)
> DEBUG1 [1855/2057]: Fail to receive status reply on sock 33 (in consumer_recv_status_reply() at consumer.c:58)
> Error: Pushing metadata
> Error: Handling metadata request
> Error: Health error occurred in thread_manage_consumer
> DEBUG1 [1855/2057]: consumer thread cleanup completed (in thread_manage_consumer() at main.c:1194)
> DEBUG1 [1855/1858]: Clean command context structure (in clean_command_ctx() at main.c:538)
> DEBUG1 [1855/1858]: Accepting client command ... (in thread_manage_clients() at main.c:3629)
>
>
> -----Original Message-----
> From: jeremie.galarneau at gmail.com [mailto:jeremie.galarneau at gmail.com] On Behalf Of Jérémie Galarneau
> Sent: den 9 augusti 2013 16:55
> To: Stanislav Vovk
> Cc: lttng-dev at lists.lttng.org
> Subject: Re: [lttng-dev] one sessiond for multiuser system
>
> 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



-- 
Jérémie Galarneau
EfficiOS Inc.
http://www.efficios.com