[Lxc-users] lxcpath

[Serge Hallyn]

Quoting Stéphane Graber (stgraber at ubuntu.com):
> On 03/02/2013 06:45 PM, Papp Tamas wrote:
> > On 02/25/2013 02:56 PM, Serge Hallyn wrote:
> >>
> >> Quoting Papp Tamas (tompos at martos.bme.hu):
> >>> hi Serge and Others,
> >>>
> >>> lxc version: 0.9.0.alpha3
> >>>
> >>> lxcpath=/data/lxc
> >>>
> >>> tank/lxc/ltest on /tank/lxc/ltest type zfs (rw,noatime)
> >>>
> >>>
> >>> # sh -x /usr/bin/lxc-create -n ltest -t ubuntu
> >>> + . /usr/share/lxc/lxc.functions
> >>> + globalconf=/etc/lxc/lxc.conf
> >>> + bindir=/usr/bin
> >>> + templatedir=/usr/share/lxc/templates
> >>> + lxcinitdir=/usr/lib/x86_64-linux-gnu
> >>> + get_default_lxcpath
> >>> + grep -v ^# /etc/lxc/lxc.conf
> >>> + grep [ \t]*lxcpath[ \t]*=
> >>> + awk -F= { print $2 }
> >>> + lxc_path=/data/lxc
> >>> + backingstore=_unset
> >>> + fstype=ext4
> >>> + fssize=500M
> >>> + vgname=lxc
> >>> + custom_rootfs=
> >>> + [ 4 -gt 0 ]
> >>> + opt=-n
> >>> + shift
> >>> + optarg_check -n ltest
> >>> + [ -z ltest ]
> >>> + lxc_name=ltest
> >>> + shift
> >>> + [ 2 -gt 0 ]
> >>> + opt=-t
> >>> + shift
> >>> + optarg_check -t ubuntu
> >>> + [ -z ubuntu ]
> >>> + lxc_template=ubuntu
> >>> + shift
> >>> + [ 0 -gt 0 ]
> >>> + wantedhelp=0
> >>> + [ -z /data/lxc ]
> >>> + [ ! -r /data/lxc ]
> >>> + [ -z ltest ]
> >>> + [ -z  ]
> >>> + lvname=ltest
> >>> + id -u
> >>> + [ 0 != 0 ]
> >>> + [ -n  ]
> >>> + :
> >>> + [ -d /data/lxc/ltest ]
> >>> + basename /usr/bin/lxc-create
> >>> + echo lxc-create: 'ltest' already exists
> >>> lxc-create: 'ltest' already exists
> >>> + exit 1
> >>>
> >>>
> >>>
> >>> So a new container cannot be created, because the directory already exists, as it's on an own
> >>> filesystem.
> >>
> >> Yes lxcpath does not address the case of wanting to import an existing
> >> rootfs.  Only the case of wanting to keep the rootfs on a different
> >> partition.  But you can now keep the container config in
> >> /data/lxc/ltest/config instead of under /var/lib/lxc/ltest, which
> >> might keep things (like where the fstab should be) less confused.
> > 
> > I'm not sure, I understand, what you get to point. Or maybe I miss that:)
> > 
> > This is, what I do:
> > 
> > 1. I create a partition or zfs volume for the container to keep
> > 2. lxc-create -t ubuntu
> > 
> > 
> > What about this small change?
> > 
> > --- /usr/bin/lxc-create.ORIG	2013-03-03 00:38:19.749777404 +0100
> > +++ /usr/bin/lxc-create	2013-03-03 00:39:17.050725908 +0100
> > @@ -205,7 +205,7 @@
> >           ;;
> >   esac
> > 
> > -if [ -d "$lxc_path/$lxc_name" ]; then
> > +if [ -d "$lxc_path/$lxc_name/rootfs" ]; then
> >       echo "$(basename $0): '$lxc_name' already exists" >&2
> >       exit 1
> >   fi
> > 
> > 
> > Though not perfect at all since it cannot handle the case, when there is a mountpoint inside the 
> > rootfs (eg. rootfs/var).
> > But I think with this change it would work way comfortable.
> > 
> > 
> > tamas
> 
> 
> The change proposed above wouldn't work for cases where you create the
> container config in /var/lib/lxc/<container> but don't store the rootfs
> there. For example when using lvm-backed containers.

... lvm backed containers seems like a bad example?

> In such case, a second call to lxc-create would completely destroy the
> config of the existing container...

But given that we have a configurable lxcpath with system-wide
configurable default, is there any good reason left do do that?

> I guess we could do 'if [ -f "$lxc_path/$lxc_name/config" ]' instead,
> which should work fine for any lxc-create generated container.
> 
> -- 
> Stéphane Graber
> Ubuntu developer
> http://www.ubuntu.com
> 



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