Open Stack

Excerpts from Flavio Percoco's message of 2014-09-18 02:07:09 -0700:
> Greetings,
> 
> If I recall correctly, Heat was planning to adopt Zaqar regardless of
> the result of the graduation attempt (please correct me if I'm wrong).
> Based on this assumption, I'd like to start working on a plan forward to
> make this integration happen.
> 
> So far, these are the use cases I've collected from past discussions:
> 
> * Notify  heat user before an action is taken, and after - Heat may want
> to wait  for a response before proceeding - notifications not
> necessarily needed  and signed read-only queues might help, but not
> necessary
>     * For integrating with user's tools
>         * Monitoring
>         * Control surface
>         * Config management tools
>     * Does not require notifications and/or read-only/signed queue endpoints
>         *[These may be helpful, but were not brought up in the discussion]

This is perhaps the most important need. It would be fully satisfied by
out of order messages as long as we have guaranteed "at least once"
delivery.

[for the rest, I've reduced the indent, as I don't think they were meant
to be underneath the one above]

> * Subscribe to an aggregate feed of interesting events from other
>   open-stack components (such as Nova)
>     * Heat is often deployed in a different place than other
>       components and doesn't have access to the AMQP bus
>     * Large  deployments consist of multiple AMQP brokers, and there
>       doesn't seem to  be a nice way to aggregate all those events [need to
>       confirm]

I've also heard tell that Ceilometer wants to be a sieve for these. I've
no idea why that makes sense, but I have heard it said.

> * Push metadata updates to os-collect-config agent running in
>   servers, instead of having them poll Heat

This one is fine with an out of order durable queue.

> 
> 
> Few questions that I think we should start from:
> 
> - Does the above list cover Heat's needs?
> - Which of the use cases listed above should be addressed first?
> - Can we split the above into milestones w/ due dates?
> 
> 
> Thanks,
> Flavio
>