[Lxc-users] Networking between host and container

[Marko Anastasov]

On Fri, Dec 28, 2012 at 1:57 PM, Stéphane Graber <stgraber at ubuntu.com>wrote:

> On 12/28/2012 01:20 PM, Marko Anastasov wrote:
> >
> > On Dec 28, 2012, at 11:47 , Stéphane Graber <stgraber at ubuntu.com> wrote:
> >
> >> On 12/28/2012 10:27 AM, Marko Anastasov wrote:
> >>> Hello,
> >>>
> >>> What is the best way to broadcast container's hostname to host? I want
> to be able to ssh from host into the container using its hostname as
> handle, instead of an IP address.
> >>>
> >>> I'm using the default template in Ubuntu 12.04. I have made a
> container template that I want to reuse. My first attempt was to install
> avahi-daemon on host and container, replace hostname in container config,
> fstab, /etc/hosts, /etc/hostname and dhclient.conf with some unique id.
> This worked in VirtualBox, but for some reason not on a real machine.
> >>>
> >>> Thanks,
> >>> Marko
> >>
> >> Not exactly an answer to your question, but should be an answer to your
> >> problem anyway:
> >>
> http://www.stgraber.org/2012/07/17/easily-ssh-to-your-containers-and-vms-on-ubuntu-12-04-lts/
> >
> > Hi Stéphane,
> >
> > I should note that I'm working with a server installation of 12.04, and
> packages dnsmasq and resolvconf are actually not installed by default. I've
> added them but I'm not sure what's next. So I think I'm missing some
> configuration that you assume on your blog.
>
> LXC in Ubuntu comes with dnsmasq-base and resolvconf was introduced by
> default by me in Ubuntu 12.04, so you have it for sure or you're not
> using a supported Ubuntu installation (resolvconf is part of
> ubuntu-minimal).
>
> >
> > Eg output of host $(echo %h | sed "s/\\.lxc//g") 10.0.3.1 is
> >
> > Using domain server:
> > Name: 10.0.3.1
> > Address: 10.0.3.1#53
> > Aliases:
> >
> > Host %h not found: 3(NXDOMAIN)
>
> That's because once put in your ssh config, the %h will be replaced by
> the name of your container.
>
> Try "host <container name> 10.0.3.1", that'll return the IP address of
> your container as long as it's using DHCP for its IP configuration.
>
>
Thanks for your help Stéphane. This all works. A quick recap:

 - no additional packages aside from dnsmasq-base and resolvconf on host
are needed
 - "host container-name 10.0.3.1" is a way of getting the container's IP
address; Stéphane's blog post shows a clever way of using that in ssh
config to address containers by their name

I guess the next step forward would be to have the container name
resolveable as a network name system-wide (again, having more knowledge
about the networking stack would help). For my purposes it isn't absolutely
necessary though.

Marko
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