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Greetings from an ancient thread (but the most recent on to openstack-dev
about localfs that I can find).

In 2014, which were heady times, we decided that we couldn't deprecate
nova.virt.disk.vfs.localfs because we theorised that FreeBSD and containers
would soon need it. Oh, and xenapi uses it a little too.

It is now three years later, and there has been some recent thought given
to deprecating localfs again, which I bumped into when I chose this code as
the first candidate for a prototype privsep user inside the nova codebase
[1].

I think we therefore need to have this conversation again. Do we still have
any clear use cases for localfs? Where does guestfs not run at the moment?
Or did I waste my time privsep'ing localfs?

Thanks,
Michael

1: https://review.openstack.org/#/c/459166/





On Wed, Sep 24, 2014 at 7:04 PM, Daniel P. Berrange <berrange at redhat.com>
wrote:

> On Wed, Sep 24, 2014 at 08:26:44AM +1000, Michael Still wrote:
> > On Tue, Sep 23, 2014 at 8:58 PM, Daniel P. Berrange <berrange at redhat.com>
> wrote:
> > > On Tue, Sep 23, 2014 at 02:27:52PM +0400, Roman Bogorodskiy wrote:
> > >>   Michael Still wrote:
> > >>
> > >> > Hi.
> > >> >
> > >> > I know we've been talking about deprecating
> nova.virt.disk.vfs.localfs
> > >> > for a long time, in favour of wanting people to use libguestfs
> > >> > instead. However, I can't immediately find any written documentation
> > >> > for when we said we'd do that thing.
> > >> >
> > >> > Additionally, this came to my attention because Ubuntu 14.04 is
> > >> > apparently shipping a libguestfs old enough to cause us to emit the
> > >> > "falling back to localfs" warning, so I think we need Ubuntu to
> catch
> > >> > up before we can do this thing.
> > >> >
> > >> > So -- how about we remove localfs early in Kilo to give Canonical a
> > >> > release to update libguestfs?
> > >> >
> > >> > Thoughts appreciated,
> > >> > Michael
> > >>
> > >> If at some point we'd start moving into getting FreeBSD supported as a
> > >> host OS for OpenStack, then it would make sense to keep localfs for
> that
> > >> configuration.
> > >>
> > >> libguestfs doesn't work on FreeBSD yet. On the other hand, localfs
> > >> code in Nova doesn't look like it'd be hard to port.
> > >
> > > Yep, that's a good point and in fact applies to Linux too when
> considering
> > > the non-KVM/QEMU drivers libvirt supports. eg if your host does not
> have
> > > virtualization and you're using LXC for container virt, then we need to
> > > have localfs still be present. Likewise if running Xen.
> > >
> > > So we definitely cannot delete or even deprecate it unconditionally. We
> > > simply want to make sure localfs isn't used when Nova is configured to
> > > run QEMU/KVM via libvirt.
> > >
> > > So if we take the config option approach I suggested, then we'd set a
> > > default value for the vfs_impl parameter according to which libvirt
> > > driver you have enabled.
> >
> > I'm glad we've had this thread, because I hadn't thought of the
> > FreeBSD case at all. In that case I wonder if we want to water down
> > the warning we currently log in this case:
> >
> >                 LOG.warn(_LW("Unable to import guestfs"
> >                              "falling back to VFSLocalFS"))
> >
> > If feel like it should be an info if we know some platforms will
> > always have this occur. I know this is a minor thing, but this came to
> > my attention because at lease one operator was concerned by seeing
> > that warning in their logs.
>
> If we take my suggested approach of using a fixed impl based on libvirt
> driver type, then we wouldn't have fallback & so not see this warning.
> Even when we do have fallback, we should only warn if libguestfs is
> installed, but not working.
>
>
> Regards,
> Daniel
> --
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> :|
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>



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