Open Stack

> From: Mike Spreitzer <mspreitz at us.ibm.com>
> To: "OpenStack Development Mailing List \(not for usage questions\)"
> <openstack-dev at lists.openstack.org>
> Date: 03/04/2014 07:10
> Subject: Re: [openstack-dev] [heat] metadata for a HOT
>
> Zane Bitter <zbitter at redhat.com> wrote on 04/02/2014 05:36:43 PM:
>
> > I think that if you're going to propose a new feature, you should at
> > least give us a clue who you think is going to use it and what for ;)
>
> I was not eager to do that yet because I have not found a fully
> satisfactory answer yet, at this point I am exploring options.  But
> the problem I am thinking about is how Heat might connect to a
> holistic scheduler (a scheduler that makes a joint decision about a
> bunch of resources of various types).  Such a scheduler needs input
> describing the things to be scheduled and the policies to apply in
> scheduling; the first half of that sounds a lot like a Heat
> template, so my thoughts go in that direction.  But the HOT language
> today (since https://review.openstack.org/#/c/83758/ was merged)
> does not have a place to put policy that is not specific to a
singleresource.

I think you bring up a specific use case here, i.e. applying "policies" for
placement/scheduling when deploying a stack. This is just a thought, but I
wonder whether it would make more sense to then define a specific extension
to HOT instead of having a generic metadata section and stuffing everything
that does not fit into other places into metadata.

I mean, the use case Keith brought up are completely different (UI and user
related), and I understand both use cases. But is the idea to put just
everything into metadata, or would different classes of use cases justify
different section? The latter would enforce better documentation of
semantics. If everyhing goes into a metadata section, the contents also
need to be clearly specified. Otherwise, the resulting template won't be
portable. Ok, the standard HOT stuff will be portable, but not the
metadata, so no two users will be able to interpret it the same way.

>
> > IIRC this has been discussed in the past and the justifications for
> > including it in the template (as opposed to allowing metadata to be
> > attached in the ReST API, as other projects already do for many things)

> > were not compelling.
>
> I see that Keith Bray mentioned https://wiki.openstack.org/wiki/
> Heat/StackMetadata and https://wiki.openstack.org/wiki/Heat/UI in
> another reply on this thread.  Are there additional places to look
> to find that discussion?
>
> I have also heard that there has been discussion of language
> extension issues.  Is that a separate discussion and, if so, where
> can I read it?
>
> Thanks,
> Mike
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