[ClusterLabs] Failed 'virsh' call when test RA run by crm_resource (con't)

[Reid Wahl]

On Wed, Jan 11, 2023 at 8:11 PM Madison Kelly <mkelly at alteeve.com> wrote:
>
> Hi all,
>
>    There was a lot of sub-threads, so I figured it's helpful to start a
> new thread with a summary so far. For context; I have a super simple
> perl script that pretends to be an RA for the sake of debugging.
>
> https://pastebin.com/9z314TaB
>
>    I've had variations log environment variables and confirmed that all
> the variables in the direct call that work are in the crm_resource
> triggered call. There are no selinux issues logged in audit.log and
> selinux is permissive. The script logs the real and effective UID and
> GID and it's the same in both instances. Calling other shell programs
> (tested with 'hostname') run fine, this is specifically crm_resource ->
> test RA -> virsh call.
>
>    I ran strace on the virsh call from inside my test script (changing
> 'virsh.good' to 'virsh.bad' between running directly and via
> crm_resource. The strace runs made six files each time. Below are
> pastebin links with the outputs of the six runs in one paste, but each
> file's output is in it's own block (search for file: to see the
> different file outputs)
>
> Good/direct run of the test RA:
> - https://pastebin.com/xtqe9NSG
>
> Bad/crm_resource triggered run of the test RA:
> - https://pastebin.com/vBiLVejW
>
> Still absolutely stumped.

The strace outputs show that your bad runs are all getting stopped
with SIGTTOU. If you've never heard of that, me either.

https://www.gnu.org/software/libc/manual/html_node/Job-Control-Signals.html

Macro: int SIGTTOU

    This is similar to SIGTTIN, but is generated when a process in a
background job attempts to write to the terminal or set its modes.
Again, the default action is to stop the process. SIGTTOU is only
generated for an attempt to write to the terminal if the TOSTOP output
mode is set; see Output Modes.


Maybe this has something to do with the buffer settings in the perl
script(?). It might be worth trying a version that doesn't fiddle with
the outputs and buffer settings.

I don't know which difference between your environment and mine is
relevant here, such that I can't reproduce the issue using your test
script. It works perfectly fine for me.

Can you run `stty -a | grep tostop`? If there's a minus sign
("-tostop"), it's disabled; if it's present without a minus sign
("tostop"), it's enabled, as best I can tell.

I'm just spitballing here. It's disabled by default on my machine...
but even when I enable it, crm_resource --validate works fine. It may
be set differently when running under crm_resource.

>
> --
> Madison Kelly
> Alteeve's Niche!
> Chief Technical Officer
> c: +1-647-471-0951
> https://alteeve.com/
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-- 
Regards,

Reid Wahl (He/Him)
Senior Software Engineer, Red Hat
RHEL High Availability - Pacemaker