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Hello again Stephen,

As usual, responses in-line!


On 04/17/2014 08:39 PM, Stephen Balukoff wrote:
> Hello German and Brandon!
>
> Responses in-line:
>
>
> On Thu, Apr 17, 2014 at 3:46 PM, Brandon Logan 
> <brandon.logan at rackspace.com <mailto:brandon.logan at rackspace.com>> wrote:
>
>     Stephen,
>     I have responded to your questions below.
>
>
>     On 04/17/2014 01:02 PM, Stephen Balukoff wrote:
>>     Howdy folks!
>>
>>     Based on this morning's IRC meeting, it seems to me there's some
>>     contention and confusion over the need for "single call"
>>     functionality for load balanced services in the new API being
>>     discussed. This is what I understand:
>>
>>     * Those advocating "single call" are arguing that this simplifies
>>     the API for users, and that it more closely reflects the users'
>>     experience with other load balancing products. They don't want to
>>     see this functionality necessarily delegated to an orchestration
>>     layer (Heat), because coordinating how this works across two
>>     OpenStack projects is unlikely to see success (ie. it's hard
>>     enough making progress with just one project). I get the
>>     impression that people advocating for this feel that their
>>     current users would not likely make the leap to Neutron LBaaS
>>     unless some kind of functionality or workflow is preserved that
>>     is no more complicated than what they currently have to do.
>     Another reason, which I've mentioned many times before and keeps
>     getting ignored, is because the more primitives you add the longer
>     it will take to provision a load balancer.  Even if we relied on
>     the orchestration layer to build out all the primitives, it still
>     will take much more time to provision a load balancer than a
>     single create call provided by the API.  Each request and response
>     has an inherent time to process.  Many primitives will also have
>     an inherent build time. Combine this in an environment that
>     becomes more and more dense, build times will become very
>     unfriendly to end users whether they are using the API directly,
>     going through a UI, or going through an orchestration layer. This
>     industry is always trying to improve build/provisioning times and
>     there are no reasons why we shouldn't try to achieve the same goal.
>
>
> Noted.
>
>>     * Those (mostly) against the idea are interested in seeing the
>>     API provide primitives and delegating "higher level" single-call
>>     stuff to Heat or some other orchestration layer. There was also
>>     the implication that if "single-call" is supported, it ought to
>>     support both simple and advanced set-ups in that single call.
>>     Further, I sense concern that if there are multiple ways to
>>     accomplish the same thing supported in the API, this redundancy
>>     breeds complication as more features are added, and in developing
>>     test coverage. And existing Neutron APIs tend to expose only
>>     primitives. I get the impression that people against the idea
>>     could be convinced if more compelling reasons were illustrated
>>     for supporting single-call, perhaps other than "we don't want to
>>     change the way it's done in our environment right now."
>     I completely disagree with "we dont want to change the way it's
>     done in our environment right now".  Our proposal has changed the
>     way our current API works right now.  We do not have the notion of
>     primitives in our current API and our proposal included the
>     ability to construct a load balancer with primitives individually.
>     We kept that in so that those operators and users who do like
>     constructing a load balancer that way can continue doing so.  What
>     we are asking for is to keep our users happy when we do deploy
>     this in a production environment and maintain a single create load
>     balancer API call.
>
>
> There's certainly something to be said for having a less-disruptive 
> user experience. And after all, what we've been discussing is so 
> radical a change that it's close to starting over from scratch in many 
> ways.
Yes, we assumed that starting from scratch would be the case at least as 
far as the API is concerned.
>
>>
>>     I've mostly stayed out of this debate because our solution as
>>     used by our customers presently isn't "single-call" and I don't
>>     really understand the requirements around this.
>>
>>     So! I would love it if some of you could fill me in on this,
>>     especially since I'm working on a revision of the proposed API.
>>     Specifically, what I'm looking for is answers to the following
>>     questions:
>>
>>     1. Could you please explain what you understand single-call API
>>     functionality to be?
>     Single-call API functionality is a call that supports adding
>     multiple features to an entity (load balancer in this case) in one
>     API request.  Whether this supports all features of a load
>     balancer or a subset is up for debate.  I prefer all features to
>     be supported.  Yes it adds complexity, but complexity is always
>     introduced by improving the end user experience and I hope a good
>     user experience is a goal.
>
>
> Got it. I think we all want to improve the user experience.
>
>>
>>     2. Could you describe the simplest use case that uses single-call
>>     API in your environment right now? Please be very specific--
>>      ideally, a couple examples of specific CLI commands a user might
>>     run, or API (along with specific configuration data) would be great.
>     http://docs.rackspace.com/loadbalancers/api/v1.0/clb-devguide/content/Create_Load_Balancer-d1e1635.html
>
>     This page has many different ways to configure a load balancer
>     with one call.  It ranges from a simple load balancer to a load
>     balancer with a much more complicated configuration.  Generally,
>     if any of those features are allowed on a load balancer then it is
>     supported through the single call.
>>
> I'm going to use example 4.10 as the "simplest" case I'm seeing there. 
> (Also because I severely dislike XML ;) )
>
>>     3. Could you describe the most complicated use case that your
>>     single-call API supports? Again, please be very specific here.
>     Same data can be derived from the link above.
>
>
> Ok, I'm actually not seeing and complicated examples, but I'm guessing 
> that any attributes at the top of the page could be expanded on 
> according the the syntax described.
>
> Hmmm...  one of the draw-backs I see with a "one-call" approach is 
> you've got to have really good syntax checking for everything right 
> from the start, or (if you plan to handle primitives one at a time) a 
> really solid roll-back strategy if anything fails or has problems, 
> cleaning up any primitives that might already have been created before 
> the whole call completes.
>
> The alternative is to not do this with primitives... but then I don't 
> see how that's possible either. (And certainly not easy to write tests 
> for:  The great thing about small primitives is their methods tend to 
> be easier to unit test.)

Yes, most of those features that are in that document for a load 
balancer can be done in the single create call.
There is definitely more validation added on for this call.  The 
roll-back strategy is solid but its really pretty trivial especially 
when the code is designed well enough.  Thought would have to go into 
making the code the best, but I don't see this as a bad thing at all.  
I'd prefer the code base be thoroughly thought out and designed to 
handle complexities elegantly.

If the API only allowed primitives, and creating a load balancer in one 
call is done through an orchestration layer, that orchestration layer 
would then be responsible for rolling back.  This could cause problems 
because rolling back may involve performing actions that are not exposed 
through the API and so the orchestration layer has no way to do a proper 
rollback.
>
>>
>>     4. What percentage of your customer base are used to using
>>     single-call functionality, and what percentage are used to
>>     manipulating primitives?
>     100% but just like others it is the only way to create a load
>     balancer in our API.  So this data doesn't mean much.
>
>         Oh! One other question:
>
>         5. Should "single-call" stuff work for the lifecycle of a load
>     balancing service? That is to say, should "delete" functionality
>     also clean up all primitives associated with the service?
>
>     How we were thinking was that it would just "detach" the
>     primitives from the load balancer but keep them available for
>     association with another load balancer. A user would only be able
>     to actually delete a primitive if it went through the root
>     primitive resource (i.e. /pools, /vips).  However, this is
>     definitely up for debate and there are pros and cons to doing it
>     both ways.  If the system completely deletes the primitives on the
>     deletion of the load balancer, then the system has to handle when
>     one of those primitives is being shared with another load balancer.
>
>
> That makes sense--  but I think it could end in disaster for the poor 
> fool who isn't aware of that and makes "deploying load balancing 
> services" part of their continuous integration run. In very little 
> time, they'd have bazillions of abandoned primitives. At the same 
> time, it doesn't make sense to delete shared primitives, lest you 
> horribly break things for service B by nuking service A.
>
> So, going with the principle of least surprise here, it seems to me 
> that most people attempting a delete in a single call are going to 
> want all the non-shared primitives deleted (in a cascading effect) 
> unless they specify that they want the primitives preserved. It would 
> be great if there were a good way to set this as an option somehow 
> (though I know an HTTP DELETE doesn't allow for this kind of 
> flexibility-- maybe something appended to the URI if you want to 
> preserve non-shared primitives?)
>
> Deleting a primitive (ie. not using single-call) should clearly just 
> delete the primitive. Though, of course, it would be nice to specify 
> (using some flag) that the delete should be ignored if the primitive 
> happens to be shared.

This is definitely an option as well and gives you the best of both 
worlds.  As long as there is a way to detach a primitive from the load 
balancer, this would be a good option (especially if not doing the 
cascading delete can be specified).  I do like the idea of it cleaning 
up everything for the user, just like German said when a user leaves it 
could make life easier for someone.  Though, I think the best option is 
the one that makes the most sense from an end-user's perspective, in 
which case I would need to spend more time weighing the pros and cons of 
all three.
>
>
>
> On Thu, Apr 17, 2014 at 2:23 PM, Eichberger, German 
> <german.eichberger at hp.com <mailto:german.eichberger at hp.com>> wrote:
>
>     Hi Stephen,
>
>     1. Could you please explain what you understand single-call API
>     functionality to be?
>
>     From my perspective most of our users will likely create load
>     balancers via  a web interface. Thought not necessary, having a
>     single API call makes it easier to develop the web interface.
>
>     For the "expert" users I envision them to create a load balancer,
>     tweak with the settings, and when they arrive at the load balancer
>     they need to automate the creation of it. So if they have to
>     create several objects with multiple calls in a particular order
>     that is far too complicated and makes the learning curve very
>     steep from the GUI to the API. Hence, I like being able to do one
>     call and get a functioning load balancer. I like that aspect from
>     Jorge's proposal. On the other hand making a single API call
>     contain all possible settings might make it too complex for the
>     casual user who just wants some feature activated the GUI doesn't
>     provide....
>
>
> That makes sense. Are you envisioning having a function in the GUI to 
> "show me the CLI or API command to do this" once a user has ticked all 
> the check-boxes they want and filled in the fields they want?
>
> For our power users-- I could see some of them occasionally updating 
> primitives. Probably the most common API command we see has to do with 
> users who have written their own scaling algorithms which add and 
> remove members from a pool as they see load on their app servers 
> change throughout the day (and spin up / shut down app server clones 
> in response).
>
>     2. Could you describe the simplest use case that uses single-call
>     API in your environment right now?
>
>     Please be very specific--  ideally, a couple examples of specific
>     CLI commands a user might run, or API (along with specific
>     configuration data) would be great.
>
>     http://libra.readthedocs.org/en/latest/api/rest/load-balancer.html#create-a-new-load-balancer
>
>
>
> Got it. Looks straight-forward.
>
>     5. Should "single-call" stuff work for the lifecycle of a load
>     balancing service? That is to say, should "delete" functionality
>     also clean up all primitives associated with the service?
>
>     Yes. If a customer doesn't like a load balancer any longer one
>     call will remove it. This makes a lot of things easier:
>
>     -GUI development -- one call does it all
>
>     -Cleanup scripts: If a customer leaves us we just need to run
>     delete on a list of load balancers -- ideally if the API had a
>     call to delete all load balancers of a specific user/project that
>     would be even better J
>
>     -The customer can tear down test/dev/etc. load balancer very quickly
>
>
> What do you think of my "conditional cascading delete" idea (ie. nuke 
> everything but shared primitives) above for the usual / least surprise 
> case?
>
> Thanks,
> Stephen
>
>
>
> -- 
> Stephen Balukoff
> Blue Box Group, Inc.
> (800)613-4305 x807
>
>
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