[lxc-devel] LXC Autostart and order...

Stéphane Graber stgraber at ubuntu.com
Thu May 15 20:07:15 UTC 2014


On Thu, May 15, 2014 at 03:58:10PM -0400, Michael H. Warfield wrote:
> On Wed, 2014-05-14 at 13:19 +0000, Serge Hallyn wrote:
> > Quoting Michael H. Warfield (mhw at WittsEnd.com):
> > > This is more directed at Stéphane but other thoughts and comments are
> > > welcome.
> > > 
> > > I'm also looking at the lxc-autostart code and I've noticed a couple of
> > > things...
> > > 
> > > The -g / --groups option is only a single instance option.  Should this
> > > allow for multiple options?  i.e.  "-g ,onboot -g Mygroup"  Right now,
> > > it looks like last one wins.
> 
> > Yes, supporting multiple options is a desired feature, I think Stéphane
> > had said that if you want to pursue a patch to do that that'd be great.
> 
> That patch is now ready.  I'll be submitting it before too long.
> 
> In light of the fact that the other autostart patches from Dwight and I
> have not been acked or pushed and that this patch affects those patches
> (obviates the need to call lxc-autostart twice), I'll role them up into
> a larger patch.

Sounds good, thanks!

I'm back to work tomorrow (until Tuesday) so I'm planning on doing a bit
of catching up on those patches and push whatever's left to push.

> 
> > > That could be handled just by appending multiple instances, separated by
> > > commas, when processing the command line, even though we later break the
> > > list apart into a list.
> > > 
> > > It looks like the sort ordering is not taking into account group
> > > membership.  It goes through the list of containers ordered by the
> > > lxc.start.order parameter and sorts them without regard to what groups
> > > may have been specified.  That means that "onboot,myboot" is the same as
> > > "myboot,onboot" and that "WittsEnd-web,WittsEnd-DNS" is the same as
> > > "WittsEnd-DNS,Wittsend.web".
> > > 
> > > So the -g option is then order independent for the specified groups.  Is
> > > that our desired behavior?  If so, that should be documented or there
> > 
> > I suspect it is, then if you want one group started before the other you
> > can just call lxc-autostart multiple times.
> > 
> > > may be some undesirable results if dependencies fail.  That gives me
> > > some heartburn that we may need to document that you need to group your
> > > orderings to insure that members of one group do not get started before
> > > members of other groups.  Just doesn't feel like a clean paradigm there.
> > 
> > It could be more flexible than always starting them in the group order.
> > 
> > Although I guess actually I prefer going the other way:  allow containers
> > to be associated with multiple groups, and only allow one group name to
> > be specified with lxc-autostart.  Then if you want groups x1 and x2 started
> > at the same time, you just add all x1 and x2 containers to group y1 as well
> > and start that group.
> > 
> > That seems simpler to think about, but as I'm not one of the power users
> > here I'll defer to Stéphane and yourself.
> > 
> > > It's that loop that runs through the containers after the qsort and then
> > > queries lists_contain_common_entry() that's doing that.  That's where
> > > adding a catch for the NULL group may be a challenge.  Special case
> > > where there's a empty string in the group list and no membership in any
> > > group in the lists_contain_common_entry() would catch that.
> > > 
> > > Regards,
> > > Mike
> > > -- 
> > > Michael H. Warfield (AI4NB) | (770) 978-7061 |  mhw at WittsEnd.com
> > >    /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
> > >    NIC whois: MHW9          | An optimist believes we live in the best of all
> > >  PGP Key: 0x674627FF        | possible worlds.  A pessimist is sure of it!
> > > 
> > 
> > 
> > 
> > > _______________________________________________
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> > > lxc-devel at lists.linuxcontainers.org
> > > http://lists.linuxcontainers.org/listinfo/lxc-devel
> > 
> > _______________________________________________
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> > http://lists.linuxcontainers.org/listinfo/lxc-devel
> > 
> 
> -- 
> Michael H. Warfield (AI4NB) | (770) 978-7061 |  mhw at WittsEnd.com
>    /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
>    NIC whois: MHW9          | An optimist believes we live in the best of all
>  PGP Key: 0x674627FF        | possible worlds.  A pessimist is sure of it!
> 



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-- 
Stéphane Graber
Ubuntu developer
http://www.ubuntu.com
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