[Lxc-users] what's the difference in lxc-attach

[Michael H. Warfield]

On Fri, 2011-07-15 at 18:36 +0300, Ramez Hanna wrote: 
> On Fri, Jul 15, 2011 at 6:04 PM, Michael H. Warfield <mhw at wittsend.com>wrote:
> 
> > On Fri, 2011-07-15 at 17:50 +0300, Ramez Hanna wrote:
> > > how can i check if lxc-attach is not working because of the kernel or
> > > because of other bug?
> > >
> > > On Thu, Apr 7, 2011 at 10:09 AM, Cedric Le Goater <legoater at free.fr>
> > wrote:
> > >
> > > > On 04/07/2011 07:46 AM, Ramez Hanna wrote:
> > > > > from a post that i found earlier in the archive
> > > > > subject "entering a container" by Daniel Lezcano
> > > > >
> > > > > i cannot see the differece between lxc-attach and lxc-execute
> > > > > could someone explain?
> > > >
> > > > lxc-execute creates a container and exec's a command/application
> > > > inside it (see manual).
> > > >
> > > > lxc-attach enters a *running* container and exec's a command inside
> > > > it (manual soon to come). This ability of creating an exogenous
> > > > process inside a container requires a kernel patchset.
> >
> > Has that patch set even made it into a release?  If so, what version is
> > it in and what version are you running.  It does not work on my F15
> > system with a 2.6.38 kernel.  If it has not made it into a released
> > kernel, have you built a custom kernel with it?

> I don't know about that patch, so hence my question if there is anyway to
> know from the host if that capability is available

From what I can tell, based on some threads from back in March, the
patchset has not been merged into the upstream kernel at this time and
is almost certainly NOT in 2.6.38.*.

I'm currently running Fedora 15 2.6.38.8-32.fc15.x86_64 which does not
have the patch and lxc-attach gives this error:

[root at forest Alcove]# lxc-attach --name Alcove
lxc-attach: Does this kernel version support 'attach' ?
lxc-attach: failed to enter the namespace

That's probably about the best answer you're going to get.

From what I can tell, the last patchset is here:

http://lxc.sourceforge.net/patches/linux/2.6.38/

If you want it, you're probably going to have to build yourself a custom
kernel with it patched in.

Some of the patches have been merged into the upstream kernel but it's
not clear to me if we'll have to wait for 3.0 to be released to see them
but I suspect that to be the case.  We're currently sitting at 3.0-rc7
on that one.  2.6.39.3 is released and stable nut I have no clue what's
in there.  2.6.38 is currently at 2.6.38.8, which is what we see in F15
so it is what it is.

> > > > C.
> > > >

Regards,
Mike
-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
   /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
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