[Libguestfs] Notes on building libguestfs in a systemd-nspawn container

[Daniel P. Berrange]

On Thu, Jan 30, 2014 at 05:07:23PM +0530, Kashyap Chamarthy wrote:
> On 01/30/2014 04:38 PM, Daniel P. Berrange wrote:
> 
> [. . .]
> 
> >>
> >> Despite reading from the `systemd-nspawn` man page:
> >>
> >>  ". . .kernel modules may not be loaded from within the container."
> >>
> >> I purposefully tried from inside the container:
> > 
> > With container based virt there is only one kernel image,
> 
> Noted, that's one of the main aspects, right, of containers: single
> Kernel (also a single point of attack-surface; no custom Kernels, etc)[1]
> 
> But I see the use-case of systemd-nspawn: quick development/debugging
> just like chroot, but better.
> 
> > so any
> > modules you want must be loaded in the host. Libvirt "passthrough"
> > of char/block devices simply involves libvirt doing mknod in the
> > /dev tmpfs it sets up. The container itself is blocked from doing
> > any 'mknod' calls since that'd be a security risk. Hence you must
> > list any desired device nodes in the XML config.
> 
> Thanks for the explanation. I have to try libvirt-lxc tools next. Also
> on my todo-list to try:
> 
>   $ virt-sandbox mock
> 
>   [Build a package]
> 
> I see that the above provides a default SELinux 'seclabel' element. Have
> to test yet.
> 
> Meanwhile, I stumbled across an upstream thread[2][3] of yours this
> morning & learnt re: a regression with user namespaces containers

Nb user namespaces aren't relevant here. Nothing you're using / trying
here involves user namespaces at all.

Daniel
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