[Lxc-users] veth interface not deleted?

[Serge Hallyn]

Quoting Fajar A. Nugraha (list at fajar.net):
> On Mon, Sep 30, 2013 at 11:29 PM, Serge Hallyn <serge.hallyn at ubuntu.com>wrote:
> 
> > Quoting Serge Hallyn (serge.hallyn at ubuntu.com):
> > > Quoting Jäkel, Guido (G.Jaekel at dnb.de):
> >
> 
> 
> > > > >> By the other hand if I prevent inside the container by
> > configuration that eth0 is driven down, then right at the termination of
> > the lxc
> > > > >>process the ssh terminal quits and also, the veth disappears. Beside
> > from the test, I noticed the similar effect on other "in-real-usage"-
> > > > >>containers with connection to listeners inside: The veth stays a
> > while until theses inbounding connection have died.
> > > >
> > > > ... , but what causes this "helpful" effect? I guess that the open
> > connection are reset, maybe by the stack as a result of closing the network
> > namespace. But why this will happen only if the interface was left up
> > (which is the anormal case)?
> > >
> > > You bring up a good point - we should be able to inject a tcp rst to
> > > force it to close.  So we may in fact be able to watch for this and
> > > fix it from userspace in lxc.  (in fact that may be the only place
> > > where it really makes sense to do - since we *know* the container
> > > should be dying.)
> >
> > If someone wants to experiment with this and send a patch with
> > a good example of how to test the patch - that would rock.
> >
> 
> Would injecting tcp rst really be necessary? In my test, doing "ip link
> del" on the host side of the interface ALWAYS succeed, no matter what the
> state the guest container's interface is.
> 
> Serge, do you have the particular commit ids for "lxc.network.script.down"
> support? Backporting that would probably be the best step for me to try.

commit 74a2b5864f2ece87bf522d1c1cbd590dc24c0c53
Author: Jan Kiszka <jan.kiszka at siemens.com>
Date:   Mon Jul 9 19:15:48 2012 +0200

    Add network-down script

-serge