[lxc-users] fetching application update out of container's space

[Tycho Andersen]

On Thu, Jun 11, 2015 at 12:07:21AM +0200, Genco Yilmaz wrote:
> On Wed, Jun 10, 2015 at 11:06 PM, Tycho Andersen <
> tycho.andersen at canonical.com> wrote:
> 
> > On Wed, Jun 10, 2015 at 09:22:10PM +0200, Genco Yilmaz wrote:
> > > Hi,
> > >    I have been playing with containers for a few days only and deployed
> > > several to test some networking features. I have searched on the net to
> > get
> > > an answer but couldn't find any post/page yet. Issue is that I set up a
> > > small LAB
> > > containers of which has no internet access. If I need to install an
> > > application e.g apache2
> > > I attach to the container like;
> > >
> > > #lxc-attach -n container1
> > > container1#apt-get install apache2
> > >
> > > but for this to work, I add a veth peer to let the container access
> > outside
> > > network (This isn't something I prefer to do as I need to isolate these
> > > containers)
> >
> > Why not just run an apt mirror on the isolated network?
> >
> > > I wonder if there is any way to install this app from the master host i.e
> > > by using master
> > > host's network space but install the app on the container something like
> > > this imaginary command;
> > >
> > > #*lxc-run* -n container -c "apt-get install apache2"
> > >
> > > i.e pulling the application from repository on the master space but
> > pushing
> > > it onto the container.
> > >
> > > There is lxc-execute, lxc-attach but they all run inside container's
> > space
> > > which doesn't work for me.
> >
> > You might like the -s option to lxc-attach.
> >
> > Tycho
> >
> > > Thanks,
> > >
> > > Genco.
> >
> >
> Hi Tycho,
>  Thanks for the reply. I have tried this one now. Apparently I didn't
> notice this option:) but there seems to be an issue with name resolution.
> Not sure what I am doing wrong though but although I am not attaching to
> container's network namespace,
> system still checks the resolv.conf file inside the container instead of
> host's resolv.conf. As you can see,
> if I add the nameserver to container resolv.conf, name resolution works. Is
> this expected or there is a missing/incorrect option in my command?

This is expected, because you're using the container's mount
namespace, and thus the tools look at the container's
/etc/resolv.conf.

Tycho

> or is
> it because of the MOUNT namespace. Because of this name resolution issue,
> apt-get also fails
> 
> 
> 
> root at vhost3:~# lsb_release -a
> No LSB modules are available.
> Distributor ID: Ubuntu
> Description:    Ubuntu 14.04.2 LTS
> Release:        14.04
> Codename:       trusty
> 
> root at vhost3:~# ping archive.ubuntu.com -c 1
> PING archive.ubuntu.com (91.189.91.15) 56(84) bytes of data.
> 64 bytes from likho.canonical.com (91.189.91.15): icmp_seq=1 ttl=51
> time=81.6 ms
> 
> --- archive.ubuntu.com ping statistics ---
> 1 packets transmitted, 1 received, 0% packet loss, time 0ms
> rtt min/avg/max/mdev = 81.607/81.607/81.607/0.000 ms
> 
> root at vhost3:~# lxc-attach -n LAB1016-co -e -s 'UTSNAME|MOUNT|PID|IPC' --
> ping archive.ubuntu.com -c 1
> ping: unknown host archive.ubuntu.com
> 
> root at vhost3:~# lxc-attach -n LAB1016-co -e -s 'UTSNAME|MOUNT|PID|IPC' --
> ping 91.189.91.15 -c 1
> PING 91.189.91.15 (91.189.91.15) 56(84) bytes of data.
> 64 bytes from 91.189.91.15: icmp_seq=1 ttl=51 time=80.7 ms
> 
> --- 91.189.91.15 ping statistics ---
> 1 packets transmitted, 1 received, 0% packet loss, time 0ms
> rtt min/avg/max/mdev = 80.739/80.739/80.739/0.000 ms
> 
> root at vhost3:~# cat /etc/resolv.conf
> # Dynamic resolv.conf(5) file for glibc resolver(3) generated by
> resolvconf(8)
> #     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
> nameserver 8.8.8.8
> search example.com
> 
> root at vhost3:~# lxc-attach -n LAB1016-co
> root at LAB1016-co:~# echo "nameserver 8.8.8.8" >> /etc/resolv.conf
> root at LAB1016-co:~# exit
> exit
> root at vhost3:~# lxc-attach -n LAB1016-co -e -s 'UTSNAME|MOUNT|PID|IPC' --
> ping archive.ubuntu.com -c 1
> PING archive.ubuntu.com (91.189.91.14) 56(84) bytes of data.
> 64 bytes from orobas.canonical.com (91.189.91.14): icmp_seq=1 ttl=52
> time=87.2 ms
> 
> --- archive.ubuntu.com ping statistics ---
> 1 packets transmitted, 1 received, 0% packet loss, time 0ms
> rtt min/avg/max/mdev = 87.250/87.250/87.250/0.000 ms

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