[Lxc-users] lxc-wait doesn't notice container shutdown

[Michael H. Warfield]

On Mon, 2013-07-08 at 18:27 +1000, Christoph Willing wrote: 
> On 05/07/2013, at 9:53 PM, Serge Hallyn <serge.hallyn at ubuntu.com> wrote:
> 
> > Quoting Christoph Willing (cwilling at users.sourceforge.net):
> >> Since upgrading from lxc-0.7.5 to 0.9.0 I have a problem with lxc-wait.
> >> 
> >> Previously, scripts containing an lxc-wait for the STOPPED state would continue as expected when the nominated container shut itself down i.e. the script received the STOPPED state and lxc-wait exits. However with 0.9.0, lxc-wait doesn't seem to receive the STOPPED state when the container shuts itself down  - the scripts just keep waiting. I can run lxc-stop manually, whereupon the waiting script then sees that the container gets the message and continues as before.
> >> 
> >> On the other hand, the same scripts see the RUNNING state of a newly started container and continue execution as before.
> >> 
> >> So although lxc-wait is working (receives states sent explicitly via lxc-start/stop), it no longer receives any indication from the container that is is shutting down.
> >> 
> >> Is this new behaviour expected in 0.9.0?
> > 
> > No it sounds unexpected.  Would you be able to code the above into a
> > little test script to reproduce?  (something like
> > 
> > 	sudo lxc-create -t ubuntu -n x1
> > 	sudo lxc-start -n x1 -d
> > 	sudo nohup lxc-wait -s STOPPED -n x1 > /tmp/outout 2>&1 &
> > 	pid=$!
> > 	sudo lxc-sttach -n x1 -- poweroff
> > 	tail /tmp/outout
> > 	ps -p $pid && echo "lxc-wait still running - FAIL"
> > 	ps -p $pid || echo "lxc-wait exited - PASS"
> > 
> > )
> > 
> > Also please tell us which distro+release you're on and the exact package
> > or upstream git version (there have been very recent changes...)  Is
> > lxc-wait a script or a program in yours?  (which lxc-wait;  file `which lxc-wait`)
> 
> I found & fixed the problem but, for interest, the affected distro is Slackware "current" (the next release), using package lxc-0.9.0-x86_64-1 from which lxc-wait is a program:
> 
> chris at current:~$ which lxc-wait;  file `which lxc-wait`
> /usr/bin/lxc-wait
> /usr/bin/lxc-wait: ELF 64-bit LSB  executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), stripped
> 
> 
> Since there is no distributed lxc-slackware template, I've made my own
> which I install locally. I've been using the same basic template for
> about the last 3 Slackware releases and have had no problems. Part of
> the the template's execution involves patching some of Slackware's
> default rc.d scripts for use in the container. For some reason, the
> patching removes the reboot/poweroff calls in rc.6 (the shutdown
> script). I don't recall now why that was done - whether it was
> mistaken or intentional - yet everything had all worked as expected
> until now. Anyway, assuming it was a mistake and so changing my
> template to leave the reboot/poweroff calls intact has fixed the
> problem - lxc-wait receives the STOPPED state again.

Historically, removing the calls to "reboot/poweroff" were done, at the
very least, to circumvent the "read-only" remounts of mounted file
systems in the host.  We've been plagued by that problem on and off
again for some time and never really nailed it.  I think the latest
fixes for dealing with systemd based systems is ultimately incompatible
with some of the host workarounds (bind mounts) which some of use were
using to avoid that problem as well.  There may have been other reasons
but that was, most emphatically, one of them.

> chris

Regards,
Mike
-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
   /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
   NIC whois: MHW9          | An optimist believes we live in the best of all
 PGP Key: 0x674627FF        | possible worlds.  A pessimist is sure of it!
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