[Libguestfs] virt-sparsify failed (was: [oVirt Jenkins] ovirt-system-tests_basic-suite-master_nightly - Build # 479 - Failure!)

Mon Nov 9 07:16:33 UTC 2020

On Wed, Oct 14, 2020 at 8:54 AM Yedidyah Bar David <didi at redhat.com> wrote:
>
> On Tue, Oct 13, 2020 at 8:40 PM Richard W.M. Jones <rjones at redhat.com> wrote:
> >
> > On Tue, Oct 13, 2020 at 07:56:29PM +0300, Nir Soffer wrote:
> > > On Tue, Oct 13, 2020 at 7:15 PM Richard W.M. Jones <rjones at redhat.com> wrote:
> > > >
> > > > On Tue, Oct 13, 2020 at 06:45:42PM +0300, Nir Soffer wrote:
> > > > > I think this is the right solution - when virt-something tool fails,
> > > > > it should log the reason for the failure - the error that caused the
> > > > > tool to fail. I'm not sure this is easy to do as the failing code
> > > > > run inside a special VM. Maybe the code running in the VM should log
> > > > > the output in a machine readable way, so once an error is detected
> > > > > virt-something can report the error as the reason, without running
> > > > > in debug mode.
> > > >
> > > > All the virt-* tools that I've written have a non-zero exit code and
> > > > print an error message on stderr when they fail.  Errors from inside
> > > > the appliance are propagated to the library and thence to the tool
> > > > correctly.
> > > >
> > > > I think the best thing to do is:
> > > >
> > > >  - spool up stdout + stderr from the tool
> > > >
> > > >  - if the exit code != 0, save the spooled output for analysis
> > > >
> > > >  - if the exit code == 0, discard it (or keep it if you like)
> > >
> > > This is what we already do, and the result is not helpful. If you look
> > > at the log message in the previous message, basically the only
> > > info about the error is:
> > >
> > >     libguestfs error: guestfs_launch failed
> > >
> > > I don't see what we can do with this error message.
> >
> > Right, so in this particular instance the error message would tell us
> > that you should run libguestfs-test-tool because your qemu/kernel/etc
> > is broken in some way :-/
> >
> > There's not a particularly good answer here if you don't want to ever
> > use LIBGUESTFS_DEBUG/LIBGUESTFS_TRACE, but perhaps you could run
> > libguestfs-test-tool if you see any error which matches the substring
> > /guestfs_launch/ ?
>
> Another (orthogonal?) option:
>
> Make LIBGUESTFS_DEBUG/LIBGUESTFS_TRACE log elsewhere, not to stdout/err
> (e.g. some other file descriptor, or to a file passed via env or whatever).
> This way, it might make sense for vdsm to always pass these vars, continue
> logging all stdout/err, and log/keep debug/trace logs only on errors.

This now happened again:

https://jenkins.ovirt.org/job/ovirt-system-tests_basic-suite-master_nightly/565/

https://jenkins.ovirt.org/job/ovirt-system-tests_basic-suite-master_nightly/565/artifact/exported-artifacts/test_logs/basic-suite-master/lago-basic-suite-master-host-1/_var_log/vdsm/vdsm.log

2020-11-09 01:05:42,031-0500 INFO  (jsonrpc/4) [api.host] FINISH
getAllVmIoTunePolicies return={'status': {'code': 0, 'message':
'Done'}, 'io_tune_policies_dict':
{'c189ecb3-8f2e-4726-8766-7d2d9b514687': {'policy': [],
'current_values': [{'name': 'vda', 'path':
'/rhev/data-center/mnt/192.168.200.4:_exports_nfs_share1/1d093232-d41e-483f-a915-62f8db3c972f/images/e7ee6417-b319-4d84-81a5-5d77cbce2385/710d2c10-e6b7-4d16-bd37-50a9d4e14a80',
'ioTune': {'total_bytes_sec': 0, 'read_bytes_sec': 0,
'write_bytes_sec': 0, 'total_iops_sec': 0, 'write_iops_sec': 0,
'read_iops_sec': 0}}]}}} from=::1,34002 (api:54)
2020-11-09 01:05:42,038-0500 DEBUG (jsonrpc/4) [jsonrpc.JsonRpcServer]
Return 'Host.getAllVmIoTunePolicies' in bridge with
{'c189ecb3-8f2e-4726-8766-7d2d9b514687': {'policy': [],
'current_values': [{'name': 'vda', 'path':
'/rhev/data-center/mnt/192.168.200.4:_exports_nfs_share1/1d093232-d41e-483f-a915-62f8db3c972f/images/e7ee6417-b319-4d84-81a5-5d77cbce2385/710d2c10-e6b7-4d16-bd37-50a9d4e14a80',
'ioTune': {'total_bytes_sec': 0, 'read_bytes_sec': 0,
'write_bytes_sec': 0, 'total_iops_sec': 0, 'write_iops_sec': 0,
'read_iops_sec': 0}}]}} (__init__:360)
2020-11-09 01:05:42,435-0500 DEBUG (tasks/3) [common.commands] FAILED:
<err> = b"virt-sparsify: error: libguestfs error: guestfs_launch
failed.\nThis usually means the libguestfs appliance failed to start
or crashed.\nDo:\n  export LIBGUESTFS_DEBUG=1 LIBGUESTFS_TRACE=1\nand
run the command again.  For further information, read:\n
http://libguestfs.org/guestfs-faq.1.html#debugging-libguestfs\nYou can
also run 'libguestfs-test-tool' and post the *complete* output\ninto a
bug report or message to the libguestfs mailing list.\n\nIf reporting
bugs, run virt-sparsify with debugging enabled and include the
\ncomplete output:\n\n  virt-sparsify -v -x [...]\n"; <rc> = 1
(commands:98)

I suggest that if we have come to a dead-end and no-one has any clue, then
we either patch something (vdsm?) to allow getting more information if this
happens again, or open a bug for further discussion/prioritization.

Best regards,
-- 
Didi