openstack team mailing list archive

[Erik Carlin <erik.carlin@xxxxxxxxxxxxx>]

The way I see it, there isn't a singular OpenStack API (even today there is swift, nova, and glance).  OpenStack is a suite of IaaS each with their own API – so there is a SUITE of standard OS APIs.  And each OS service should strive to define the canonical API for automating that particular service.  If I just want to run an image repo, I deploy glance.  If my SAN guy can't get storage provisioned fast enough, I deploy the OS block storage service (once we have it).  And if I want a full cloud suite, I deploy all the services.  They are loosely coupled and (ideally) independent building blocks.  Whether one chooses to front the different service endpoints with a proxy to unify them or have separate service endpoints is purely a deployment decision.  Either way, there are no competing OS APIs.  Support for 3rd party APIs (e.g. EC2) is secondary IMO, and to some degree, detrimental.  Standards are defined largely in part by ubiquity.  We want OS to become ubiquitous and we want the OS APIs to become defacto.  Supporting additional APIs (or even variations of the same API like AMQP per the other thread) doesn't help us here.  I would love to see the community rally behind a per service standard OS REST API that we can own and drive.

To that end, the goal as I see it is to launch canonical OpenStack Compute (nova) and Image (glance) APIs with Cactus.  In Diablo, we would then work to introduce separate network and block storage services with REST APIs as well.  All APIs would be independently versioned and stable.  I'm ALL for per language OpenStack bindings that implement support for the entire suite of services.

Re: extensions, it's actually the technical aspects that are driving it.  There is a tension between standards and innovation that needs to be resolved.  In addition, we need to be able to support niche functionality (e.g. Rackspace may want to support API operations related to managed services) without imposing it on everyone.  These problems are not new.  We've seen the same exact thing with OpenGL and they have a very successful extension model that has solved this.  Jorge studied this when did his PhD and has designed extensions with that in mind.  He has a presentation on extensions here<4:20
Jorge%20Williams
http://wiki.openstack.org/JorgeWilliams?action=AttachFile&do=view&target=Extensions.pdf> if you haven't seen it.  I think extensions are critically important and would encourage dialog amongst the community to come to a consensus on this.  Per my points above, I would prefer to avoid separate APIs for the same service.  Let's see if we can get behind a per service API that becomes THE defacto standard way for automating that service.

Erik

From: Justin Santa Barbara <justin@xxxxxxxxxxxx<mailto:justin@xxxxxxxxxxxx>>
Date: Fri, 18 Feb 2011 09:57:12 -0800
To: Paul Voccio <paul.voccio@xxxxxxxxxxxxx<mailto:paul.voccio@xxxxxxxxxxxxx>>
Cc: "openstack@xxxxxxxxxxxxxxxxxxx<mailto:openstack@xxxxxxxxxxxxxxxxxxx>" <openstack@xxxxxxxxxxxxxxxxxxx<mailto:openstack@xxxxxxxxxxxxxxxxxxx>>
Subject: Re: [Openstack] OpenStack Compute API 1.1

> How is the 1.1 api proposal breaking this?

Because if we launch an OpenStack API, the expectation is that this will be the OpenStack API :-)

If we support a third-party API (CloudServers or EC2), then people will continue to use their existing wrappers (e.g. jclouds)  Once there's an OpenStack API, then end-users will want to find a library for that, and we don't want that to be a poor experience.  To maintain a good experience, we either can't break the API, or we need to write and maintain a lot of proxying code to maintain compatibility.  We know we're not ready for the first commitment, and I don't think we get enough to justify the second.

> I think the proxy would make sense if you wanted to have a single api. Not all service providers will but I see this as entirely optional, not required to use the services.

But then we have two OpenStack APIs?  Our ultimate end users don't use the API, they use a wrapper library.  They want a stable library that works and is kept up to date with recent changes and don't care about what's going on under the covers.  Wrapper library authors want an API that is (1) one API and (2) stable with reasonable evolution, otherwise they'll abandon their wrapper or not update it.

> The extensions mechanism is the biggest change, iirc.

I'm not a big fan of the extensions idea, because it feels more like a reflection of a management goal, rather than a technical decision ("OpenStack is open to extensions")  Supporting separate APIs feels like a better way to do that.  I'm very open to be corrected here, but I think we need to see code that wants to use the extension API and isn't better done as a separate API.  Right now I haven't seen any patches, and that makes me uneasy.





On Fri, Feb 18, 2011 at 9:29 AM, Paul Voccio <paul.voccio@xxxxxxxxxxxxx<mailto:paul.voccio@xxxxxxxxxxxxx>> wrote:
The spec for 1.0 and 1.1 are pretty close. The extensions mechanism is the biggest change, iirc.

I think the proxy would make sense if you wanted to have a single api. Not all service providers will but I see this as entirely optional, not required to use the services.

The push to get a completed compute api is the desire move away from the ec2 api to something that we can guide, extend and vote on as a community. The sooner we do the the better.

How is the 1.1 api proposal breaking this?

From: Justin Santa Barbara <justin@xxxxxxxxxxxx<mailto:justin@xxxxxxxxxxxx>>
Date: Fri, 18 Feb 2011 09:10:19 -0800
To: Paul Voccio <paul.voccio@xxxxxxxxxxxxx<mailto:paul.voccio@xxxxxxxxxxxxx>>
Cc: Jay Pipes <jaypipes@xxxxxxxxx<mailto:jaypipes@xxxxxxxxx>>, "openstack@xxxxxxxxxxxxxxxxxxx<mailto:openstack@xxxxxxxxxxxxxxxxxxx>" <openstack@xxxxxxxxxxxxxxxxxxx<mailto:openstack@xxxxxxxxxxxxxxxxxxx>>

Subject: Re: [Openstack] OpenStack Compute API 1.1

Jay: The AMQP->REST was the re-architecting I was referring to, which would not be customer-facing (other than likely introducing new bugs.)  Spinning off the services, if this is visible at the API level, is much more concerning to me.

So Paul, I think the proxy is good because it acknowledges the importance of keeping a consistent API.  But - if our API isn't finalized - why push it out at all, particularly if we're then going to have the overhead of maintaining another translation layer?  For Cactus, let's just support EC2 and/or CloudServers 1.0 API compatibility (again a translation layer, but one we probably have to support anyway.)  Then we can design the right OpenStack API at our leisure and meet all of our goals: a stable Cactus and stable APIs.  If anyone ends up coding to a Cactus OpenStack API, we shouldn't have them become second-class citizens 3 months later.

Justin





On Fri, Feb 18, 2011 at 6:31 AM, Paul Voccio <paul.voccio@xxxxxxxxxxxxx<mailto:paul.voccio@xxxxxxxxxxxxx>> wrote:
Jay,

I understand Justin's concern if we move /network and /images and /volume
to their own endpoints then it would be a change to the customer. I think
this could be solved by putting a proxy in front of each endpoint and
routing back to the appropriate service endpoint.

I added another image on the wiki page to describe what I'm trying to say.
http://wiki.openstack.org/api_transition

I think might not be as bad of a transition since the compute worker would
receive a request for a new compute node then it would proxy over to the
admin or public api of the network or volume node to request information.
It would work very similar to how the queues work now.

pvo

On 2/17/11 8:33 PM, "Jay Pipes" <jaypipes@xxxxxxxxx<mailto:jaypipes@xxxxxxxxx>> wrote:

>Sorry, I don't view the proposed changes from AMQP to REST as being
>"customer facing API changes". Could you explain? These are internal
>interfaces, no?
>
>-jay
>
>On Thu, Feb 17, 2011 at 8:13 PM, Justin Santa Barbara
><justin@xxxxxxxxxxxx<mailto:justin@xxxxxxxxxxxx>> wrote:
>> An API is for life, not just for Cactus.
>> I agree that stability is important.  I don't see how we can claim to
>> deliver 'stability' when the plan is then immediately to destablize
>> everything with a very disruptive change soon after, including customer
>> facing API changes and massive internal re-architecting.
>>
>>
>> On Thu, Feb 17, 2011 at 4:18 PM, Jay Pipes <jaypipes@xxxxxxxxx<mailto:jaypipes@xxxxxxxxx>> wrote:
>>>
>>> On Thu, Feb 17, 2011 at 6:57 PM, Justin Santa Barbara
>>> <justin@xxxxxxxxxxxx<mailto:justin@xxxxxxxxxxxx>> wrote:
>>> > Pulling volumes & images out into separate services (and moving from
>>> > AMQP to
>>> > REST) sounds like a huge breaking change, so if that is indeed the
>>>plan,
>>> > let's do that asap (i.e. Cactus).
>>>
>>> Sorry, I have to disagree with you here, Justin :)  The Cactus release
>>> is supposed to be about stability and the only features going into
>>> Cactus should be to achieve API parity of the OpenStack Compute API
>>> with the Rackspace Cloud Servers API. Doing such a huge change like
>>> moving communication from AMQP to HTTP for volume and network would be
>>> a change that would likely undermine the stability of the Cactus
>>> release severely.
>>>
>>> -jay
>>
>>



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