Open Stack

On Thu, Jun 09, 2016 at 06:17:56PM +0100, Lucas Alvares Gomes wrote:
> Hi,
> 
> Thanks for writing it down Jim.
> 
> > So, I've been thinking about this quite a bit. We've also talked about
> > doing a v2 API (as evil as that may be) in Ironic here and there. We've
> > had lots of lessons learned from the v1 API, mostly that our API is
> > absolutely terrible for humans. I'd love to fix that (whether that
> > requires a v2 API or not is unclear, so don't focus on that).
> >
> > I've noticed that people keep talking about the Nova driver API
> > not being public/stable/whatever in this thread - let's ignore that and
> > think bigger.
> >
> > So, there's two large use cases for ironic that we support today:
> >
> > * Ironic as a backend to nova. Operators still need to interact with the
> >   Ironic API for management, troubleshooting, and fixing issues that
> >   computers do not handle today.
> >
> > * Ironic standalone - by this I mean ironic without nova. The primary
> >   deployment method here is using Bifrost, and I also call it the
> >   "better than cobbler" case. I'm not sure if people are using this
> >   without bifrost, or with other non-nova services, today. Users in this
> >   model, as I understand things, do not interact with the Ironic API
> >   directly (except maybe for troubleshooting).
> >
> > There's other use cases I would like to support:
> >
> > * Ironic standalone, without Bifrost. I would love for a deployer to be
> >   able to stand up Ironic as an end-user facing API, probably with
> >   Keystone, maybe with Neutron/Glance/Swift if needed. This would
> >   require a ton of discussion and work (e.g. ironic has no concept of
> >   tenants/projects today, we might want a scheduler, a concept of an
> >   instance, etc) and would be a very long road. The ideal solution to
> >   this is to break out the Compute API and scheduler to be separate from
> >   Nova, but that's an even longer road, so let's pretend I didn't say
> >   that and not devolve this thread into that conversation (yet).
> >
> > * Ironic as a backend to other things. Josh pointed out kubernetes
> >   somewhere, I'd love to be an official backend there. Heat today goes
> >   through Nova to get an ironic instance, it seems reasonable to have
> >   heat talk directly to ironic. Things like that. The amount of work
> >   here might depend on the application using ironic (e.g. I think k8s
> >   has it's own scheduler, heat does not, right?).
> >
> > So all that said, I think there is one big step we can take in the
> > short-term that works for all of these use cases: make our API better.
> > Make it simpler. Take a bunch of the logic in the Nova driver, and put
> > it in our API instead. spawn() becomes /v1/nodes/foo/deploy or
> > something, etc (I won't let us bikeshed those specifics in this thread).
> > Just doing that allows us to remove a bunch of code from a number of
> > places (nova, bifrost, shade, tempest(?)) and make those simpler. It
> > allows direct API users to more easily deploy things, making one API
> > call instead of a bunch (we could even create Neutron ports and such for
> > them). It allows k8s and friends to write less code. Oh, let's also stop
> > directly exposing state machine transitions as API actions, that's
> > crazy, kthx.
> >
> > I think this is what Josh is trying to get at, except maybe with a
> > separate API service in between, which doesn't sound very desirable to
> > me.
> >
> > Thoughts on this?
> >
> > Additionally, in the somewhat-short term, I'd like us to try to
> > enumerate the major use cases we're trying to solve, and make those use
> > cases ridiculously simple to deploy. Ironic is quickly becoming a
> > tangled mess of configuration options and tweaking surrounding services
> > (nova, neutron) to deploy it. Once it's figured out, it works very well.
> > However, it's incredibly difficult to figure out how to get there.
> >
> > Ultimately, I'd like someone that wants to deploy ironic in a common use
> > case, with off-the-shelf hardware, to be able to get a POC up and
> > running in a matter of hours, not days or weeks.
> >
> > Who's in? :)
> >
> 
> I agree in general with the idea but I think it needs a tad more
> context. We need to remember that Ironic (ex-Nova Baremetal) was
> created to fill a gap in OpenStack that was missing for TripleO
> project to get off the ground. That was the problem being solved and
> these aspects are reflected in the ReST API: Being admin-only, not
> "human-friendly" (standalone came later), etc...

Sorry, I didn't mean to slag on people here. In fact, I tried to come up
with a way to say "no offense" but couldn't figure the words out. Ironic
did start with a very specific use case, it's come a super long way, and
you all did what you had to do to get things going. For that I'm forever
indebted to you. :)

> > * Ironic as a backend to other things. Josh pointed out kubernetes
> >   somewhere, I'd love to be an official backend there. Heat today goes
> >   through Nova to get an ironic instance, it seems reasonable to have
> >   heat talk directly to ironic. Things like that. The amount of work
> >   here might depend on the application using ironic (e.g. I think k8s
> >   has it's own scheduler, heat does not, right?).
> 
> There was an attempt to do that before in heat, but they were refused
> at the time because it didn't fit the context above [0]. That wasn't
> the goal/scope of the project.
> 
> Now we have v1 is (almost) 3 years and during this time Ironic evolved
> a _lot_, it does covers way more use cases than we ever imagined and,
> the ReST API specially is having a hard time to cope with it.
> 
> I don't think that v2 is evil, in fact, looking at how many changes
> proposals/ideas we have in flight that not necessarily "fits" very
> well in the current API (off the top of my head): Driver composition,
> portgroups, trunk port representation, the "thing" to  management a
> group of nodes (bulk operation), composing nodes on-demand,
> claiming/reserving resources...
> 
> And now moving some of the logic from the nova ironic virt driver to
> the API. The main problem I have with this being done in the v1 is
> that the API will have two (or more) different ways of doing the
> same/similar thing, e.g, POST v1/nodes/foo/deploy Vs. PUT {'target':
> 'active'} v1/nodes/foo/states/provision.
> 
> I really think we should get all these ideas, the things we learned in
> (almost) 3 years of the v1 existence, put it all in the table and
> start solving those problems _by design_. I even believe that by
> designing a v2 that address such problems from the beggining will be
> much faster to land than trying to get it on v1. Take driver
> composition as an example, it's being around for 1.5 years and the
> spec is not approved yet, in fact we had 3 design sessions in 3
> different summits about it already.

++, I do agree we could make a v2 faster than shoehorning things into
v1. The "evil" part of my comment is around removing v1 in the future,
actually. No matter the project, it's a long hard road, and will take
years to do (and even then some tools will likely be left old and
broken).

// jim

> 
> Also, I would like to apologize for focusing on v2 in my reply even
> tho you explicitly said to "not focus on that". But, I think that it's
> the way forward.
> 
> [0] https://review.openstack.org/#/q/topic:bp/ironic-resource,n,z
> 
> Cheers,
> Lucas
> 
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