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

[Reid Wahl]

On Wed, Jan 11, 2023 at 10:27 PM Reid Wahl <nwahl at redhat.com> wrote:
>
> On Wed, Jan 11, 2023 at 10:26 PM Reid Wahl <nwahl at redhat.com> wrote:
> >
> > On Wed, Jan 11, 2023 at 10:21 PM Madison Kelly <mkelly at alteeve.com> wrote:
> > >
> > > On 2023-01-12 01:12, Reid Wahl wrote:
> > > > 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.
> > >
> > > The hell?! This is new to me also.
> > >
> > > > 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 tried removing the $|, and then I changed the script to be entirely a
> > > bash script, still hanging. I tried 'virsh --connect <method> list
> > > --all' where method was qemu:///system, qemu:///session, and
> > > ssh+qemu:///root@localhost/system, all hang. In bash or perl.
> > >
> > > > 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.
> > >
> > > -tostop is there
> > >
> > > ====
> > > [root at mk-a07n02 ~]# stty -a | grep tostop
> > > isig icanon iexten echo echoe echok -echonl -noflsh -xcase -tostop -echoprt
> > > [root at mk-a07n02 ~]#
> > > ====
> > >
> > > > 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.
> > >
> > > How do you enable it?
> >
> > With `stty tostop`
>
> If anything it should be disabled though

I'd be very interested in whether anyone else can reproduce this with
your test script

>
> >
> > It's 100% possible that this whole thing is a red herring by the way.
> > I'm looking for anything that might explain the discrepancy. SIGTTOU
> > may not be directly tied to the root cause.
> >
> > >
> > > --
> > > Madison Kelly
> > > Alteeve's Niche!
> > > Chief Technical Officer
> > > c: +1-647-471-0951
> > > https://alteeve.com/
> > >
> >
> >
> > --
> > Regards,
> >
> > Reid Wahl (He/Him)
> > Senior Software Engineer, Red Hat
> > RHEL High Availability - Pacemaker
>
>
>
> --
> Regards,
>
> Reid Wahl (He/Him)
> Senior Software Engineer, Red Hat
> RHEL High Availability - Pacemaker



-- 
Regards,

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