[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
> > >
> >
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
> > >
> > >
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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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