[Lxc-users] how to troubleshoot lxc service

[Rintcius Blok]

Hi,

I get an unusable lxc service in my host every now and then after 
creating a new container.
Only after a reboot I can get it back to normal.

This is basically what I do (12.10 host):

lxc-create -t ubuntu-cloud -n c.lxc -- --auth-key $HOME/.ssh/id_rsa.pub 
--userdata /root/webdocs.txt.gz

The problem must occur quite early in the process, since there is no 
cloudinit log file in the container yet.

Also I cannot ssh into the container:

$ ssh c.lxc
nc: getaddrinfo: Name or service not known
ssh_exchange_identification: Connection closed by remote host

And these are the only files I see in the container's var/lib/cloud:

$ cd /var/lib/lxc/c.lxc/rootfs/var/lib/cloud
$ ls -R
.:
seed

./seed:
nocloud-net

./seed/nocloud-net:
meta-data  user-data

The lxc service gets unusable in the sense that:
- I cannot stop the lxc service anymore
- containers cannot be started anymore (also simple containers)

The lxc processes stay in these state (even though I stopped and 
destroyed the containers & they do not turn up lxc-list anymore):
# ps auxwww | grep lxc
103       1179  0.0  0.0  26032   964 ?        S    11:59 0:00 dnsmasq 
-u lxc-dnsmasq --strict-order --bind-interfaces 
--pid-file=/var/run/lxc/dnsmasq.pid --conf-file= --listen-address 
10.0.3.1 --dhcp-range 10.0.3.2,10.0.3.254 --dhcp-lease-max=253 
--dhcp-no-override --except-interface=lo --interface=lxcbr0
root     12741  0.0  0.0  27540   972 ?        Ds   19:05 0:00 lxc-start 
-d -n c.lxc
root     13159  0.0  0.0  27540   976 ?        Ds   19:28 0:00 lxc-start 
-d -n e.lxc
root     13445  0.0  0.0  27540   972 ?        Ds   19:47 0:00 lxc-start 
-d -n b.lxc

Note the "D" state of the container processes (D =  Uninterruptible 
sleep (usually IO))

I don't have a reproduction path for this yet.

Any ideas how to troubleshoot this further, in order to get a 
reproduction path?

Thanks,
Rintcius