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On 09/28/2015 10:11 AM, Andrew Laski wrote:
> On 09/28/15 at 08:50am, Monty Taylor wrote:
>> On 09/28/2015 07:58 AM, Sylvain Bauza wrote:
<snip>
>>
>> Specifically, I want "nova boot" to get me a VM with an IP address. I
>> don't want it to do fancy orchestration - I want it to not need fancy
>> orchestration, because needing fancy orchestration to get a VM  on a
>> network is not a feature.
> 
> In the networking case there is a minimum of orchestration because the
> time required to allocate a port is small.  What has been requiring
> orchestration is the creation of volumes because of the requirement of
> Cinder to download an image, or be on a backend that support fast
> cloning and rely on a cache hit.  So the question under discussion is
> when booting an instance relies on another service performing a long
> running operation where is a good place to handle that.
> 
> My thinking for a while has been that we could use another API that
> could manage those things.  And be the central place you're looking for
> to pass a simple "nova boot" with whatever options are required so you
> don't have to manage the complexities of calls to
> Neutron/Cinder/Nova(current API).  What's become clear to me from this
> thread is that people don't seem to oppose that idea, however they don't
> want their users/clients to need to switch what API they're currently
> using(Nova).
> 
> The right way to proceed with this idea seems to be to by evolving the
> Nova API and potentially creating a split down the road.  And by split I
> more mean architectural within Nova, and not necessarily a split API. 
> What I imagine is that we follow the model of git and have a plumbing
> and porcelain API and each can focus on doing the right things.

Right, and I think that's a fine approach. Nova's job is "give me a
working VM". Working includes networking, persistent storage. The API
semantics for "give me a working VM" should exist in Nova.

It is also fine if there are lower level calls that tweak parts of that,
but nova boot shouldn't have to be a multi step API process for the
user. Building one working VM you can do something with is really the
entire point of Nova.

	-Sean

-- 
Sean Dague
http://dague.net