[lxc-devel] [PATCH] lxc-create: conside create succeed when container is already created

[Serge Hallyn]

Quoting Qiang Huang (h.huangqiang at huawei.com):
> On 2013/9/17 11:27, Serge Hallyn wrote:
> > Quoting Qiang Huang (h.huangqiang at huawei.com):
> >> On 2013/9/16 12:23, Stéphane Graber wrote:
> >>> On Mon, Sep 16, 2013 at 11:37:02AM +0800, Qiang Huang wrote:
> >>>> Sometimes we use:
> >>>> lxc-create -n xxx -f config
> >>>> to copy config to the default lxcpath with the rootfs already
> >>>> exist.
> >>>> But we will get error right now, so fix this.
> >>>
> >>> Hmm, I'm not sure I understand.
> >>>
> >>> Running "lxc-create -n xxx -f config" when xxx already exists is an
> >>> error and should return an error code so the current code seems
> >>> perfectly right to me.
> >>
> >> Well, it did works this way in the former lxc_create version.
> >>
> >> We used to use LXC this way:
> >> - We made a template(rootfs, config and fstab) manually.
> > 
> >>From here, can you just write a script 'lxc-homebrew' which
> > copies the rootfs+config+fstab into place, and call
> > 
> > 	lxc-create -t homebrew -n c1
> > 
> > ?
> > 
> > If you want to just copy the stuff in by hand, you can
> > do that.  You don't *have* to run lxc-create if you've done
> > everything by hand.
> 
> OK, thanks Serge.
> 
> So we are still not supposed to use lxc-create without -t option?

I just don't see the point, and I worry that people using the
common case will end up accidentally deleting existing container
data.

Well, the current code says

        /* container is already created if we have a config and rootfs.path is accessible */
        if (lxcapi_is_defined(c) && c->lxc_conf && c->lxc_conf->rootfs.path && access(c->lxc_conf->rootfs.path, F_OK) == 0)
                goto out;

Maybe what we want to do is add a '&& access(c->configfile, F_OK) to that
test?  I think that would give you what you want, and I think it's what
I really meant to say.

> Is lxc-create only used for creating templates?

For running template scripts.  Near as I can tell the only thing
you want lxc-create to do is to copy a file (the config file).
That just seems like way overkill.

-serge