[lxc-devel] [PATCH 3/9] lxc_start: ERROR if container is already running.

[Dwight Engen]

On Wed, 22 Oct 2014 14:31:15 +0000
Serge Hallyn <serge.hallyn at ubuntu.com> wrote:

> Quoting Alexandru Gheorghe (alghe.global at gmail.com):
> > On 10/21/2014 07:54 PM, Serge Hallyn wrote:
> > > Quoting Dwight Engen (dwight.engen at oracle.com):
> > >> On Tue, 21 Oct 2014 09:58:29 -0500
> > >> Tycho Andersen <tycho.andersen at canonical.com> wrote:
> > >>
> > >>> On Tue, Oct 21, 2014 at 02:54:34PM +0000, Serge Hallyn wrote:
> > >>>> Quoting Tycho Andersen (tycho.andersen at canonical.com):
> > >>>>> On Tue, Oct 21, 2014 at 02:29:28PM +0000, Serge Hallyn wrote:
> > >>>>>> Quoting Tycho Andersen (tycho.andersen at canonical.com):
> > >>>>>>> On Fri, Oct 10, 2014 at 11:16:54AM +0800, Dongsheng Yang
> > >>>>>>> wrote:
> > >>>>>>>> We should exit with a error when starting a running
> > >>>>>>>> container.
> > >>>>>>>
> > >>>>>>> Is this intentional? I just noticed it when pulling from
> > >>>>>>> master that it breaks some of my scripts. Are we sure it
> > >>>>>>> doesn't break anything else?
> > >>>>>>
> > >>>>>> Which scripts does it break?
> > >>>>>
> > >>>>> No public ones, just some that I wrote myself. Just curious
> > >>>>> if the behavior change was intentional or not (I prefer the
> > >>>>> previous behavior :)
> > >>>>
> > >>>> What exactly is the change?  Did it used to return true
> > >>>> instead of false?  The intent was simply to shortcut a bunch
> > >>>> of extra work in the case where the container was already
> > >>>> running.
> > >>>
> > >>> Yes, sorry. It used to exit 0 instead of 1 when the container
> > >>> was already running (and didn't print any ERROR or anything).
> > >>
> > >> I also find this a bit inconsistent, we purposefully don't
> > >> report an error when doing stop on an already stopped container
> > >> (see the early return 0 in lxc_cmd_stop()). I think it can be
> > >> argued that its not an error since the command did what the
> > >> caller wanted (ensure the container is started/stopped).
> > > 
> > > Ok - I don't want to revert the patch, but am happy to have it
> > > return 0.
> > 
> > Why not return a different code, like 5, when is already running
> > (and trying to start)/stopped (and trying to stop it), so wrappers
> > can detect this and use the information further?
> 
> Yup, that sounds good.  I could just do it I suppose, I've just been
> waiting for someone to send a patch :)

Won't that still break shell scripts that are testing $?
 
> > Could this be useful? At least it will allow some more handling by
> > knowing if it's an error (1) or it really succeeded (0), and that is
> > already in the state wanted (5) when tried so.
> > 
> > --
> > ; Alexandru Gheorghe
> > ; alghe.global {at} gmail {dot} com
> > ; OpenPGP key ID 0xCAF985D2
> > 
> 
> 
> 
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