It boils down to two aspects:
1. How common is it for tenant to care about affinity or have more than a
single VIP used in a way that adding an additional (mandatory) construct makes
sense for them to handle?
For example if 99% of users do not care about affinity or will only use a
single VIP (with multiple listeners). In this case does adding an additional
object that tenants need to know about makes sense?
2. Scheduling this so that it can be handled efficiently by different
vendors and SLAs. We can elaborate on this F2F next week.
Can providers share their statistics to assist to understand how common are
those use cases?
Regards,
-Sam.
From: Stephen Balukoff [mailto:[email protected]]
Sent: Friday, May 09, 2014 9:26 PM
To: OpenStack Development Mailing List (not for usage questions)
Subject: Re: [openstack-dev] [Neutron][LBaaS] API proposal review thoughts
Hi Eugene,
This assumes that 'VIP' is an entity that can contain both an IPv4 address and
an IPv6 address. This is how it is in the API proposal and corresponding object
model that I suggested, but it is a slight re-definition of the term "virtual
IP" as it's used in the rest of the industry. (And again, we're not yet in
agreement that 'VIP' should actually contain two ip addresses like this.)
In my mind, the main reasons I would like to see the container object are:
* It solves the colocation / apolcation (or affinity / anti-affinity)
problem for VIPs in a way that is much more intuitive to understand and less
confusing for users than either the "hints" included in my API, or something
based off the nova blueprint for doing the same for virtual servers/containers.
(Full disclosure: There probably would still be a need for some anti-affinity
logic at the logical load balancer level as well, though at this point it would
be an operator concern only and expressed to the user in the "flavor" of the
logical load balancer object, and probably be associated with different billing
strategies. "The user wants a dedicated physical load balancer? Then he should
create one with this flavor, and note that it costs this much more...")
* From my experience, users are already familiar with the concept of what a
logical load balancer actually is (ie. something that resembles a physical or
virtual appliance from their perspective). So this probably fits into their
view of the world better.
* It makes sense for "Load Balancer as a Service" to hand out logical load
balancer objects. I think this will aid in a more intuitive understanding of
the service for users who otherwise don't want to be concerned with operations.
* This opens up the option for private cloud operators / providers to bill
based on number of physical load balancers used (if the "logical load balancer"
happens to coincide with physical load balancer appliances in their
implementation) in a way that is going to be seen as "more fair" and "more
predictable" to the user because the user has more control over it. And it
seems to me this is accomplished without producing any undue burden on public
cloud providers, those who don't bill this way, or those for whom the "logical
load balancer" doesn't coincide with physical load balancer appliances.
* Attaching a "flavor" attribute to a logical load balancer seems like a
better idea than attaching it to the VIP. What if the user wants to change the
flavor on which their VIP is deployed (ie. without changing IP addresses)? What
if they want to do this for several VIPs at once? I can definitely see this
happening in our customer base through the lifecycle of many of our customers'
applications.
* Having flavors associated with load balancers and not VIPs also allows
for operators to provide a lot more differing product offerings to the user in
a way that is simple for the user to understand. For example:
* "Flavor A" is the cheap load balancer option, deployed on a "shared"
platform used by many tenants that has fewer guarantees around performance and
costs X.
* "Flavor B" is guaranteed to be deployed on "vendor Q's Super Special
Product (tm)" but to keep down costs, may be shared with other tenants, though
not among a single tenant's "load balancers" unless the tenant uses the same
load balancer id when deploying their VIPs (ie. user has control of affinity
among their own VIPs, but no control over whether affinity happens with other
tenants). It may experience variable performance as a result, but has higher
guarantees than the above and costs a little more.
* "Flavor C" is guaranteed to be deployed on "vendor P's Even Better
Super Special Product (tm)" and is also guaranteed not to be shared among
tenants. This is essentially the "dedicated load balancer" option that gets you
the best guaranteed performance, but costs a lot more than the above.
* ...and so on.
* A logical load balancer object is a great demarcation point
<http://en.wikipedia.org/wiki/Demarcation_point> between operator concerns and
user concerns. It seems likely that there will be an operator API created, and
this will need to interface with the user API at some well-defined interface.
(If you like, I can provide a couple specific operator concerns which are much
more easily accomplished without disrupting the user experience using the
demarc at the 'load balancer' instead of at the 'VIP'.)
So what are the main arguments against having this container object? In
answering this question, please keep in mind:
* If you say "implementation details," please just go ahead and be more
specific because that's what I'm going to ask you to do anyway. If
"implementation details" is the concern, please follow this with a hypothetical
or concrete example as to what kinds of implementations this object would
invalidate simply by existing in the model, or what restrictions this object
introduces.
* If you say "I don't see a need" then you're really just asking people to
come up with a use case that is more easily solved using the logical load
balancer object rather than the VIP without the load balancer. I hope my
reasons above address this, but I'm happy to be more specific if you'd like:
Please point out how my examples above are not convincing reasons for having
this object, and I will be more specific.
Thanks,
Stephen
On Fri, May 9, 2014 at 1:36 AM, Eugene Nikanorov
<[email protected]<mailto:[email protected]>> wrote:
Hi Brandon
Let me know if I am misunderstanding this,and please explain it
further.
A single neutron port can have many fixed ips on many subnets. Since
this is the case you're saying that there is no need for the API to
define multiple VIPs since a single neutron port can represent all the
IPs that all the VIPs require?
Right, if you want to to have both ipv4 and ipv6 addresses on the VIP then it's
possible with single neutron port.
So multiple VIPs for this case are not needed.
Eugene.
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Blue Box Group, LLC
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