[openstack-dev] [Neutron][LBaaS] Unanswered questions in object model refactor blueprint

Stephen Balukoff sbalukoff at bluebox.net
Mon Jun 2 18:29:39 UTC 2014


Hi Brandon,

Apologies-- this slipped my mind last week. In any case yes, unless you've
already got something in the works, I'd be happy to take this on. But I
will need a little direction here:  Where do we actually keep the
authoritative source for API documentation?  Should I just make this a text
document that lives in the neutron-specs repository?

Also, I'm assuming we want to start with where we left off on our mailing
list / google doc discussion (with changes from the summit, ie.
loadbalancer as root) made part of this specification?

Thanks,
Stephen


On Fri, May 30, 2014 at 4:10 PM, Brandon Logan <brandon.logan at rackspace.com>
wrote:

> Stephen,
>
> Were you still planning on doing the second blueprint that will
> implement the new API calls?
>
> Thanks,
> Brandon
>
> On Thu, 2014-05-29 at 22:36 -0700, Bo Lin wrote:
> > Hi Brandon and Stephen,
> > Really thanks for your responses and i got to know it.
> >
> >
> > Thanks!
> > ---Bo
> >
> > ______________________________________________________________________
> > From: "Brandon Logan" <brandon.logan at RACKSPACE.COM>
> > To: "OpenStack Development Mailing List (not for usage questions)"
> > <openstack-dev at lists.openstack.org>
> > Sent: Friday, May 30, 2014 1:17:57 PM
> > Subject: Re: [openstack-dev] [Neutron][LBaaS] Unanswered questions in
> > object model refactor blueprint
> >
> >
> > Hi Bo,
> > Sorry, I forgot to respond but yes what Stephen said lol :)
> >
> > ______________________________________________________________________
> > From: Stephen Balukoff [sbalukoff at bluebox.net]
> > Sent: Thursday, May 29, 2014 10:42 PM
> > To: OpenStack Development Mailing List (not for usage questions)
> > Subject: Re: [openstack-dev] [Neutron][LBaaS] Unanswered questions in
> > object model refactor blueprint
> >
> >
> >
> >
> > Hi Bo--
> >
> >
> > Haproxy is able to have IPv4 front-ends with IPv6 back-ends (and visa
> > versa) because it actually initiates a separate TCP connection between
> > the front end client and the back-end server. The front-end thinks
> > haproxy is the server, and the back-end thinks haproxy is the client.
> > In practice, therefore, its totally possible to have an IPv6 front-end
> > and IPv4 back-end with haproxy (for both http and generic TCP service
> > types).
> >
> >
> > I think this is similarly true for vendor appliances that are capable
> > of doing IPv6, and are also initiating new TCP connections from the
> > appliance to the back-end.
> >
> >
> > Obviously, the above won't work if your load balancer implementation
> > is doing something "transparent" on the network layer like LVM load
> > balancing.
> >
> >
> > Stephen
> >
> >
> >
> >
> > On Wed, May 28, 2014 at 9:14 PM, Bo Lin <linb at vmware.com> wrote:
> >         Hi Brandon,
> >
> >         I have one question. If we support LoadBalancer to Listener
> >         relationship M:N, then one listener with IPV4 service members
> >         backend may be shared by a loadbalancer instance with IPV6
> >         forntend. Does it mean we also need to provide IPV6 - IPV4
> >         port forwarding functions in LBaaS services products? Does
> >         iptables or most LBaaS services products such as haproxy or so
> >         on provide such function? Or I am just wrong in some technique
> >         details on these LBaaS products.
> >
> >
> >         Thanks!
> >
> >         ______________________________________________________________
> >         From: "Vijay B" <os.vbvs at gmail.com>
> >
> >         To: "OpenStack Development Mailing List (not for usage
> >         questions)" <openstack-dev at lists.openstack.org>
> >
> >         Sent: Thursday, May 29, 2014 6:18:42 AM
> >
> >         Subject: Re: [openstack-dev] [Neutron][LBaaS] Unanswered
> >         questions in object model refactor blueprint
> >
> >
> >         Hi Brandon!
> >
> >
> >         Please see inline..
> >
> >
> >
> >
> >
> >
> >
> >         On Wed, May 28, 2014 at 12:01 PM, Brandon Logan
> >         <brandon.logan at rackspace.com> wrote:
> >                 Hi Vijay,
> >
> >                 On Tue, 2014-05-27 at 16:27 -0700, Vijay B wrote:
> >                 > Hi Brandon,
> >                 >
> >                 >
> >                 > The current reviews of the schema itself are
> >                 absolutely valid and
> >                 > necessary, and must go on. However, the place of
> >                 implementation of
> >                 > this schema needs to be clarified. Rather than make
> >                 any changes
> >                 > whatsoever to the existing neutron db schema for
> >                 LBaaS, this new db
> >                 > schema outlined needs to be implemented for a
> >                 separate LBaaS core
> >                 > service.
> >                 >
> >
> >                 Are you suggesting a separate lbaas database from the
> >                 neutron database?
> >                 If not, then I could use some clarification. If so,
> >                 I'd advocate against
> >                 that right now because there's just too many things
> >                 that would need to
> >                 be changed.  Later, when LBaaS becomes its own service
> >                 then yeah that
> >                 will need to happen.
> >
> >
> >         v> Ok, so as I understand it, in this scheme, there is no new
> >         schema or db, there will be a new set of tables resident in
> >         neutron_db schema itself, alongside legacy lbaas tables. Let's
> >         consider a rough view of the implementation.
> >
> >
> >         Layer 1 - We'll have a new lbaas v3.0 api in neutron, with the
> >         current lbaas service plugin having to support it in addition
> >         to the legacy lbaas extensions that it already supports. We'll
> >         need to put in new code anyway that will process the v3.0
> >         lbaas api no matter what our approach is.
> >         Layer 2 - Management code that will take care of updating the
> >         db with entities in pending_create, then invoking the right
> >         provider driver, choosing/scheduling the plugin drivers or the
> >         agent drivers, invoking them, getting the results, and
> >         updating the db.
> >         Layer 3 - The drivers themselves (either plugin drivers (like
> >         the HAProxy namespace driver/Netscaler) or plugin drivers +
> >         agent drivers).
> >
> >
> >         While having the new tables sit alongside the legacy tables is
> >         one way to implement the changes, I don't see how this
> >         approach leads to a lesser amount of changes overall. Layer 2
> >         above will be the major place where changes can be
> >         complicated. Also, it will be confusing to have two sets of
> >         lbaas tables in the same schema.
> >
> >
> >         I don't want a separate lbaas database under neutron, and
> >         neither do I want it within neutron. I'm not suggesting that
> >         we create a db schema alone, I'm saying we must build it with
> >         the new LBaaS service (just like neutron itself when it got
> >         created). If we don't do this now, we'll end up reimplementing
> >         the logic implemented in neutron for the new lbaas v3.0 API
> >         all over again for the new core LBaaS service. We'd rather do
> >         it in the new one in one effort.
> >
> >
> >
> >         I could be missing some constraints that drive taking the
> >         former approach - please help me understand those - I don't
> >         want to be discounting any one approach without thorough
> >         consideration. Right now, it looks to me like this approach is
> >         being taken only to accommodate the HAProxy namespace driver.
> >         Really that is the only driver which seems to be very
> >         intertwined with neutron in the way it uses namespaces.
> >
> >
> >
> >
> >                 >
> >                 > What we should be providing in neutron is a switch
> >                 (a global conf)
> >                 > that can be set to instruct neutron to do one of two
> >                 things:
> >                 >
> >                 >
> >                 > 1. Use the existing neutron LBaaS API, with the
> >                 backend being the
> >                 > existing neutron LBaaS db schema. This is the status
> >                 quo.
> >                 > 2. Use the existing neutron LBaaS API, with the
> >                 backend being the new
> >                 > LBaaS service. This will invoke calls not to
> >                 neutron's current LBaaS
> >                 > code at all, rather, it will call into a new set of
> >                 proxy "backend"
> >                 > code in neutron that will translate the older LBaaS
> >                 API calls into the
> >                 > newer REST calls serviced by the new LBaaS service,
> >                 which will write
> >                 > down these details accordingly in its new db schema.
> >                 As long as the
> >                 > request and response objects to legacy neutron LBaaS
> >                 calls are
> >                 > preserved as is, there should be no issues. Writing
> >                 unit tests should
> >                 > also be comparatively more straightforward, and old
> >                 functional tests
> >                 > can be retained, and newer ones will not clash with
> >                 legacy code.
> >                 > Legacy code itself will work, having not been
> >                 touched at all. The
> >                 > blueprint for the db schema that you have referenced
> >                 >
> >                 (
> https://review.openstack.org/#/c/89903/5/specs/juno/lbaas-api-and-objmodel-improvement.rst)
> should be implemented for this new LBaaS service, post reviews.
> >                 >
> >
> >                 I think the point of this blueprint is to get the API
> >                 and object model
> >                 less confusing for the Neutron LBaaS service plugin.
> >                  I think it's too
> >                 early to create an LBaaS service because we have not
> >                 yet cleaned up the
> >                 tight integration points between Neutron LBaaS and
> >                 LBaaS.  Creating a
> >                 new service would require only API interactions
> >                 between Neutron and this
> >                 LBaaS service, which currently is not possible due to
> >                 these tight
> >                 integration points.
> >
> >
> >         v> The tight integration points between LBaaS and neutron that
> >         I see are:
> >
> >
> >         1. The usage of namespaces.
> >         2.  L2 and L3 plumbing within the namespaces and tracking them
> >         in the neutron and lbaas tables,
> >         3. Plugin driver and agent driver scheduling
> >         framework/mechanism for LB drivers.
> >         4. The way drivers directly update the neutron db, which I
> >         think makes for a lack of clear functional demarcation.
> >
> >
> >         Regardless of how we use the new API and db model, will
> >         namespaces be used? If they still need to be supported, the
> >         tight integration isn't going to go anywhere.
> >
> >
> >         This is why I think it will be best to keep the legacy drivers
> >         within neutron, and not give an option to newer deployments to
> >         use that concurrently with the new lbaas core service. The
> >         changes will be lesser this way because we won't touch legacy
> >         code.
> >
> >
> >
> >         While I fully understand that we're trying to change the way
> >         we look at the lbaas deployments, and the db object model is
> >         an effort towards that, we need to ensure that the execution
> >         is kept elegant as well. For drivers for lb solutions like f5
> >         or Netscaler, these pain points can be done away with because
> >         they do their own network provisioning and we keep track of
> >         them only to clean up (especially for virtual appliance
> >         solutions).
> >
> >
> >         It will however mean that we'll have the additional task of
> >         implementing the new core service before we can use the new db
> >         object model. I say we should just go for that effort and make
> >         it happen.
> >
> >
> >
> >
> >
> >
> >                 >
> >                 > The third option would be to turn off neutron LBaaS
> >                 API, and use the
> >                 > new LBaaS core service directly, but for this we can
> >                 simply disable
> >                 > neutron lbaas, and don't need a config parameter in
> >                 neutron.
> >                 >
> >                 >
> >                 > Implementing this db schema within neutron instead
> >                 will be not just
> >                 > complicated, but a huge effort that will go waste in
> >                 future once the
> >                 > new LBaaS service is implemented. Also, migration
> >                 will unnecessarily
> >                 > retain the same steps needed to go from legacy
> >                 neutron LBaaS to the
> >                 > new core LBaaS service in this approach (twice, in
> >                 succession) in case
> >                 > for any reason the version goes from legacy neutron
> >                 LBaaS -> new
> >                 > neutron LBaaS -> new LBaaS core service.
> >
> >                 I totally agree that this is technical debt, but I
> >                 believe it is the
> >                 best option we have right now since LBaaS needs to
> >                 live in the Neutron
> >                 code and process because of the tight integration
> >                 points.  Since this
> >                 object model refactor has been slated for Juno, and
> >                 these tight
> >                 integration points may or may not be cleaned up by
> >                 Juno, staying within
> >                 Neutron seems to be the best option right now.
> >
> >
> >         v> As I described above, I think the tight integration points
> >         are best kept in legacy code and not carried over to the new
> >         implementation. The cleanest way to do it would be to clearly
> >         demarcate neutron related operations (L2/L3) from LBaaS. But I
> >         am keen to get your views on what the difficult integration
> >         points are so that I get a better understanding of the
> >         motivations behind keeping the new tables in neutron.
> >
> >
> >
> >
> >         Regards,
> >         Vijay
> >
> >
> >
> >
> >                 >
> >                 >
> >                 > Going forward, the legacy neutron LBaaS API can be
> >                 deprecated, and the
> >                 > new API that directly contacts the new LBaaS core
> >                 service can be used.
> >                 >
> >                 >
> >                 > We have discussed the above architecture previously,
> >                 but outside of
> >                 > the ML, and a draft of the blueprint for this new
> >                 LBaaS core service
> >                 > is underway, and is a collation of all the
> >                 discussions among a large
> >                 > number of LBaaS engineers including yourself during
> >                 the summit - I
> >                 > will be posting it for review within a couple of
> >                 days, as planned.
> >                 >
> >                 >
> >                 >
> >                 >
> >                 > Regards,
> >                 > Vijay
> >                 >
> >                 >
> >                 > On Tue, May 27, 2014 at 12:32 PM, Brandon Logan
> >                 > <brandon.logan at rackspace.com> wrote:
> >                 >         Referencing this blueprint:
> >                 >
> >
> https://review.openstack.org/#/c/89903/5/specs/juno/lbaas-api-and-objmodel-improvement.rst
> >                 >
> >                 >         Anyone who has suggestions to possible
> >                 issues or can answer
> >                 >         some of
> >                 >         these questions please respond.
> >                 >
> >                 >
> >                 >         1. LoadBalancer to Listener relationship M:N
> >                 vs 1:N
> >                 >         The main reason we went with the M:N was so
> >                 IPv6 could use the
> >                 >         same
> >                 >         listener as IPv4.  However this can be
> >                 accomplished by the
> >                 >         user just
> >                 >         creating a second listener and pool with the
> >                 same
> >                 >         configuration.  This
> >                 >         will end up being a bad user experience when
> >                 the listener and
> >                 >         pool
> >                 >         configuration starts getting complex (adding
> >                 in TLS, health
> >                 >         monitors,
> >                 >         SNI, etc). A good reason to not do the M:N
> >                 is because the
> >                 >         logic on might
> >                 >         get complex when dealing with status.  I'd
> >                 like to get
> >                 >         people's opinions
> >                 >         on this on whether we should do M:N or just
> >                 1:N.  Another
> >                 >         option, is to
> >                 >         just implement 1:N right now and later
> >                 implement the M:N in
> >                 >         another
> >                 >         blueprint if it is decided that the user
> >                 experience suffers
> >                 >         greatly.
> >                 >
> >                 >         My opinion: I like the idea of leaving it to
> >                 another blueprint
> >                 >         to
> >                 >         implement.  However, we would need to watch
> >                 out for any major
> >                 >         architecture changes in the time itis not
> >                 implemented that
> >                 >         could make
> >                 >         this more difficult than what it needs to
> >                 be.
> >                 >
> >                 >         2. Pool to Health Monitor relationship 1:N
> >                 vs 1:1
> >                 >         Currently, I believe this is 1:N however it
> >                 was suggested to
> >                 >         deprecate
> >                 >         this in favor of 1:1 by Susanne and Kyle
> >                 agreed.  Are there
> >                 >         any
> >                 >         objections to channging to 1:1?
> >                 >
> >                 >         My opinion: I'm for 1:1 as long as there
> >                 aren't any major
> >                 >         reasons why
> >                 >         there needs to be 1:N.
> >                 >
> >                 >         3. Does the Pool object need a status field
> >                 now that it is a
> >                 >         pure
> >                 >         logical object?
> >                 >
> >                 >         My opinion: I don't think it needs the
> >                 status field.  I think
> >                 >         the
> >                 >         LoadBalancer object may be the only thing
> >                 that needs a status,
> >                 >         other
> >                 >         than the pool members for health
> >                 monitoring.  I might be
> >                 >         corrected on
> >                 >         this though.
> >                 >
> >                 >
> >                 _______________________________________________
> >                 >         OpenStack-dev mailing list
> >                 >         OpenStack-dev at lists.openstack.org
> >                 >
> >
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> >                 >
> >                 >
> >                 > _______________________________________________
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> >                 >
> >
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> >
> >
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> >
> >
> > --
> > Stephen Balukoff
> > Blue Box Group, LLC
> > (800)613-4305 x807
> >
> > _______________________________________________
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-- 
Stephen Balukoff
Blue Box Group, LLC
(800)613-4305 x807
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