[openstack-dev] [Neutron][LBaaS] Unanswered questions in object model refactor blueprint
Stephen Balukoff
sbalukoff at bluebox.net
Mon Jun 2 20:03:50 UTC 2014
Hi Eugene,
Sounds good. Should I put it in neutron-specs/specs/juno or somewhere else?
Thanks,
Stephen
On Mon, Jun 2, 2014 at 12:45 PM, Eugene Nikanorov <enikanorov at mirantis.com>
wrote:
> > Where do we actually keep the authoritative source for API
> documentation?
> I think it makes sense to actually put it in the code on gerrit and
> discuss API details there, it might save another step.
>
> Thanks,
> Eugene.
>
>
>
>
> On Mon, Jun 2, 2014 at 10:29 PM, Stephen Balukoff <sbalukoff at bluebox.net>
> wrote:
>
>> 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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>
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--
Stephen Balukoff
Blue Box Group, LLC
(800)613-4305 x807
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