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On Fri, Apr 28, 2017 at 11:42:24AM +0000, Nir Soffer wrote:
On Wed, Apr 26, 2017 at 4:37 PM Niels de Vos
<ndevos(a)redhat.com> wrote:
=20
> Hi,
>
> We're trying to improve the debugability of Gluster backed VMs and one
> of the features for this is to be able to gather "statedumps". These
> statedumps include memory allocation details and other information about
> the Gluster client. QEMU is one of the applications that can be
> configured to use libgfapi.so Gluster client.
>
> Gluster provides the /var/run/gluster/ directory and the libgfapi.so
> library that qemu (in block/gluster.c) uses that. Would there be a
> problem for the "qemu" packages to use add the "qemu" user to a
> "gluster" group?
=20
=20
Yes, if we go in this way, we will have to add qemu to the gluster group =
for
for debugging gluster: urls, rbd group for rbd: url, etc. This is
not
maintainable.
Indeed, this is one of the issues that I see as well. It would also
introduce an installation order dependency, or different packages would
need to add/update different users. This seems tricky to get right.
- qemu package creates the "qemu" user
- glusterfs package creates the "gluster" group
- which package should add the "qemu" user to the "gluster" group?
- what about updating existing installations
- ...
If qemu process writes a statedump running as qemu user, it should
keep
it in the only location in the file system where qemu user can write.
This is an option we could add. It will require an configuration option
through a (to be added) libgfapi.so function, and QEMU will need to be
updated to use it. Those are not real problems, but it will not help
current users. I also thought about using getcwd() as fallback location,
but libvirt seems to run QEMU with / as working directory.
But I think the right place for this discussion is qemu-devel, not
ovirt-devel.
Yes, maybe. The request to improve debugging came from oVirt developers
or users, so I am interested to hear those opinions first. Once I have a
better feeling for an acceptible solution, I'll make sure to get the
QEMU folks on board too.
Thanks for your reply!
Niels
=20
> I'm not sure yet how this is done for other packages
> with their own users, but there would be a dependent installation order
> of some kind (needs rpm triggers?).
>
> What is your opinion on this issue, or would you recommend an other
> approach?
>
> Thanks,
> Niels
>
> PS:
https://bugzilla.redhat.com/1445569 can be used to reply as well
>
>
> From
>
http://lists.gluster.org/pipermail/gluster-devel/2017-April/052629.html:
> On Tue, Apr 25, 2017 at 07:53:06PM +0200, Niels de Vos wrote:
> > Hi,
> >
> > Recently a new ability to trigger statedumps through the Gluster-CLI =
[0]
> > has been added. This makes it possible to get statedump
from
> > applications that use gfapi. By default, statedumps are saved under
> > /var/run/gluster/... and this directory is only writable by root.
> > Applications that use gfapi do not require root permissions (like QEM=
U),
> > and therefore fail to write the statedump :-/
> >
> > One approach would be to create a "gluster" group and give the group
> > permissions to write to /var/run/gluster/... Other 'fixes' include
> > setting ACLs on the directory so that specified users can write there.
> > because many daemons have a "home directory" that does not exist, it
> > probably is not a good idea to use $HOME to store statedumps.
> >
> > What suggestions do others have?
> >
> > Thanks,
> > Niels
> >
> >
> > 0.
>
https://github.com/gluster/glusterfs/blob/master/doc/debugging/statedum= p.md
>
>
> _______________________________________________
> Devel mailing list
> Devel(a)ovirt.org
>
http://lists.ovirt.org/mailman/listinfo/devel
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