[libvirt-users] Failed to access the console after starting the lxc container
Daniel P. Berrange
berrange at redhat.com
Wed Nov 20 12:15:54 UTC 2013
On Wed, Nov 20, 2013 at 05:28:29PM +0530, Aarti Sawant wrote:
> Hello,
>
> I am starting the system container without "/" directory So that it can
> share the host /bin /sbin /lib and /lib64 and i have sepeartely mounted
> /var, /etc and /usr directory for the container
> Below is xml file
> <domain type='lxc'>
> <name>test6</name>
> <memory>102400</memory>
> <os>
> <type>exe</type>
> <init>/sbin/init</init>
Ok, so you're starting a real "init" process. By default this
won't respond to any input on the console. You need to make
sure that your init system is setup to start a mingtty process
on the console.
Typically if you're trying to share the '/' diretory between
the host & container though, you don't want to run a full
"init" system. Instead you'd want to just run a specific
application binary instead. In fact I'd go as far to
recommend against running 'init' if you're sharing '/'.
That said, I see you're setting up private /etc & /var
so you should be mostly OK from a writable file clash
POV.
If you want a full OS container installed to a new location
though, I've got a guide for this
https://www.berrange.com/posts/2013/08/12/running-a-full-fedora-os-inside-a-libvirt-lxc-guest/
> </os>
> <vcpu>1</vcpu>
> <clock offset='utc'/>
> <on_poweroff>destroy</on_poweroff>
> <on_reboot>restart</on_reboot>
> <on_crash>destroy</on_crash>
>
> <devices>
> <console type='pty'/>
> <emulator>/usr/libexec/libvirt_lxc</emulator>
> <filesystem type='mount' accessmode='passthrough'>
> <source dir='/lxc/test6/etc'/>
> <target dir='/etc'/>
> </filesystem>
>
> <filesystem type='mount' accessmode='passthrough'>
> <source dir='/lxc/test6/var'/>
> <target dir='/var'/>
> </filesystem>
> <filesystem type='mount' accessmode='passthrough'>
> <source dir='/lxc/test6/usr'/>
> <target dir='/usr'/>
> </filesystem>
>
> <filesystem type='mount' accessmode='passthrough'>
> <source dir='/pg_data/'/>
> <target dir='/pg_data'/>
> </filesystem>
>
> <filesystem type='ram' accessmode='passthrough'>
> <source usage='0' units='KiB'/>
> <target dir='/dev/shm'/>
> </filesystem>
> <interface type='bridge'>
> <source bridge='br0' />
> </interface>
> </devices>
> </domain>
>
>
> when i start the container it get start , but when i try to access console
> it get stuck
Basically you need to see why the mingetty processes aren't being
started. On F19 with systemd, it should all 'just work' from a
console POV, aside from needing to edit /etc/securetty to allow
root login per my blog above.
>
> virsh # list
> Id Name State
> ----------------------------------------------------
> 18238 test4 running
> 20435 test6 running
>
>
> virsh #
>
> virsh # start test6
> Domain test6 started
>
> virsh # console test6
> Connected to domain test6
> Escape character is ^]
>
>
> But when i mount the "/" in xml it works, i have also share host
> /bin,/sbin, /lib and /lib64.
That should not make any difference, at least with a fairly
recent libvirt. If you don't have any <filesystem> listed
with a target of '/', then libvirt will secretly add one
using source=/ and target=/.
You don't mention what version of libvirt / kernel, or host
OS you have here btw. That would be generally useful info
for troubleshooting this.
Regards,
Daniel
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