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Re: [libvirt] [PATCH] Expose name + UUID to LXC containers via env variables



On Tue, Feb 22, 2011 at 07:50:43AM -0700, Eric Blake wrote:
> On 02/22/2011 07:08 AM, Daniel P. Berrange wrote:
> > When spawning 'init' in the container, set
> > 
> >   LIBVIRT_LXC_UUID=XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX
> >   LIBVIRT_LXC_NAME=YYYYYYYYYYYY
> > 
> > to allow guest software to detect & identify that they
> > are in a container
> 
> Sounds reasonable.  Does virt-what know to look for these yet?
> 
> > @@ -109,6 +124,8 @@ static int lxcContainerExecInit(virDomainDefPtr vmDef)
> >      const char *const envp[] = {
> >          "PATH=/bin:/sbin",
> >          "TERM=linux",
> > +        uuidenv,
> > +        nameenv,
> >          NULL,
> >      };
> 
> ACK, but why aren't we using virCommand yet?

Containers are very special in their startup requirements. You can't use
a plain fork()+exec() to create them. We use clone() call with a bunch of
magic flags, and then do crazy stuff pivot_root/mount setup and finally
execve() the container init process.

Regards,
Daniel
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