[Lxc-users] eth0 not coming online in LXC environment

Wed Apr 10 08:40:19 UTC 2013

I just ran some more tests. We've got 3 servers with LXC on them, and all 3
servers encounter this same problem, when you reboot a container eth0 is
down and not visible in /run/network/ifstate (and networking  isn't
configured).  Adding eth0=eth0 to that file, manually, and restarting
networking resolves it. I did send an email a few days ago saying 1 server
was working, I don't know how it worked once, but I can clearly reproduce it
now on all servers now.

The hosts are Ubuntu 12.10 just installed, pretty close to vanilla except
for the configuration settings below.

I reproduce the issue on both a vanilla 12.04 container built from the LXC
template, and on a 12.10 container built from Ubuntu cloud (I was hoping it
was just an issue with the cloud templates, but no, it seems to be some way
I'm configuring things on the host I guess).

Any ideas on my next troubleshooting steps here? It's a royal pain to cycle
our ~8 containers so I want to address it.

# Disable lxcbr0 as it's unused.

Edit /etc/default/lxc, set USE_LXC_BRIDGE to false:

# Leave USE_LXC_BRIDGE as "true" if you want to use lxcbr0 for your
# containers. Set to "false" if you'll use virbr0 or another existing
# bridge, or mavlan to your host's NIC.
USE_LXC_BRIDGE="false"

Disable virbr0 as it's unused (a duplicate of lxcbr0)

virsh net-destroy default
virsh net-undefine default

From: Fajar A. Nugraha [mailto:list at fajar.net] 
Sent: Friday, April 05, 2013 6:00 PM
To: David Parks
Cc: LXC
Subject: Re: [Lxc-users] eth0 not coming online in LXC environment

Now that's weird!

I'm sure Serge would love to get more details about your setup (e.g.
software versions, how you create the containers, etc). In the mean time, if
you're using Ubuntu-packaged lxc, can you try:

- apt-get update and upgrade, to make sure you have latest version of kernel
and lxc

- install new container using ubuntu template: "lxc-create -t ubuntu ...."

I don't know about ubuntu-cloud template, but the normal ubuntu template
works fine for me.

-- 

Fajar

On Fri, Apr 5, 2013 at 4:13 PM, David Parks <davidparks21 at yahoo.com> wrote:

Oops, forgot that important detail, running Ubuntu 12.10 as the host OS
installed off media, and I have 12.10 running in these LXC containers built
from the Ubuntu cloud distros (12.10 64bit).  

From: Fajar A. Nugraha [mailto:list at fajar.net] 
Sent: Friday, April 05, 2013 4:09 PM
To: David Parks
Cc: LXC
Subject: Re: [Lxc-users] eth0 not coming online in LXC environment

On Fri, Apr 5, 2013 at 10:33 AM, David Parks <davidparks21 at yahoo.com> wrote:

I've got an environment set up now where the host OS has a static IP
directly connected to the LAN. I'm bridging the containers to have their own
static LAN IP as well.

When I start my container eth0 is *not* configured. If I manually add
`eth0=eth0` in /run/network/ifstate and `service restart networking`, it
gets configured properly.

After looking at dmesg output I noticed that there are (unexpected)
references to em1, which is the host's physical NIC.

The bridging all works, networking is fine, it's just when I start the
container, rebooting reproduces the problem, then manually updating ifstate
and rebooting resolves it.

I'm not sure how to configure it so it configure eth0 on reboot as I would
expect.

Well, a description on which distro/version you're running as host and
container would be nice.

Short version is if you use Ubuntu (preferably quantal/raring for newer lxc
version, but precise is also fine), then it will just work. If you use some
other combination (e.g. Centos for container), then be prepared for hickups.

I had problems with Centos container, and the "fix" was to force-clean
/var/run and /var/lock/subsys on container startup:
https://github.com/fajarnugraha/lxc/blob/centos-template/templates/lxc-cento
s.in#L90

-- 

Fajar

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