Creating a separate driver for every new need brings up a concern I have had.  
If we are to implement a separate driver for every need then the permutations 
are endless and may cause a lot drivers and technical debt.  If someone wants 
an ha-haproxy driver then great.  What if they want it to be scalable and/or 
HA, is there supposed to be scalable-ha-haproxy, scalable-haproxy, and 
ha-haproxy drivers?  Then what if instead of doing spinning up processes on the 
host machine we want a nova VM or a container to house it?  As you can see the 
permutations will begin to grow exponentially.  I'm not sure there is an easy 
answer for this.  Maybe I'm worrying too much about it because hopefully most 
cloud operators will use the same driver that addresses those basic needs, but 
worst case scenarios we have a ton of drivers that do a lot of similar things 
but are just different enough to warrant a separate driver.
________________________________
From: Susanne Balle [[email protected]]
Sent: Monday, March 24, 2014 4:59 PM
To: OpenStack Development Mailing List (not for usage questions)
Subject: Re: [openstack-dev] [Neutron][LBaaS] Neutron LBaaS, Libra and "managed 
services"

Eugene,

Thanks for your comments,

See inline:

Susanne


On Mon, Mar 24, 2014 at 4:01 PM, Eugene Nikanorov 
<[email protected]<mailto:[email protected]>> wrote:
Hi Susanne,

a couple of comments inline:



We would like to discuss adding the concept of “managed services” to the 
Neutron LBaaS either directly or via a Neutron LBaaS plug-in to Libra/HA proxy. 
The latter could be a second approach for some of the software load-balancers 
e.g. HA proxy since I am not sure that it makes sense to deploy Libra within 
Devstack on a single VM.

Currently users would have to deal with HA, resiliency, monitoring and managing 
their load-balancers themselves.  As a service provider we are taking a more 
managed service approach allowing our customers to consider the LB as a black 
box and the service manages the resiliency, HA, monitoring, etc. for them.

As far as I understand these two abstracts, you're talking about making LBaaS 
API more high-level than it is right now.
I think that was not on our roadmap because another project (Heat) is taking 
care of more abstracted service.
The LBaaS goal is to provide vendor-agnostic management of load balancing 
capabilities and quite fine-grained level.
Any higher level APIs/tools can be built on top of that, but are out of LBaaS 
scope.


[Susanne] Yes. Libra currently has some internal APIs that get triggered when 
an action needs to happen. We would like similar functionality in Neutron LBaaS 
so the user doesn’t have to manage the load-balancers but can consider them as 
black-boxes. Would it make sense to maybe consider integrating Neutron LBaaS 
with heat to support some of these use cases?


We like where Neutron LBaaS is going with regards to L7 policies and SSL 
termination support which Libra is not currently supporting and want to take 
advantage of the best in each project.
We have a draft on how we could make Neutron LBaaS take advantage of Libra in 
the back-end.
The details are available at: 
https://wiki.openstack.org/wiki/Neutron/LBaaS/LBaaS%2Band%2BLibra%2Bintegration%2BDraft

I looked at the proposal briefly, it makes sense to me. Also it seems to be the 
simplest way of integrating LBaaS and Libra - create a Libra driver for LBaaS.

[Susanne] Yes that would be the short team solution to get us where we need to 
be. But We do not want to continue to enhance Libra. We would like move to 
Neutron LBaaS and not have duplicate efforts.


While this would allow us to fill a gap short term we would like to discuss the 
longer term strategy since we believe that everybody would benefit from having 
such “managed services” artifacts built directly into Neutron LBaaS.
I'm not sure about building it directly into LBaaS, although we can discuss it.

[Susanne] The idea behind the “managed services” aspect/extensions would be 
reusable for other software LB.

For instance, HA is definitely on roadmap and everybody seems to agree that HA 
should not require user/tenant to do any specific configuration other than 
choosing HA capability of LBaaS service. So as far as I see it, requirements 
for HA in LBaaS look very similar to requirements for HA in Libra.


[Susanne] Yes. Libra works well for us in the public cloud but we would like to 
move to Neutron LBaaS and not have duplicate efforts: Libra and Neutron LBaaS. 
We were hoping to be able to take the best of Libra and add it to Neutron LBaaS 
and help shape Neutron LBaaS to fit a wider spectrum of customers/users.


There are blueprints on high-availability for the HA proxy software 
load-balancer and we would like to suggest implementations that fit our needs 
as services providers.

One example where the managed service approach for the HA proxy load balancer 
is different from the current Neutron LBaaS roadmap is around HA and 
resiliency. The 2 LB HA setup proposed 
(https://blueprints.launchpad.net/neutron/+spec/lbaas-ha-haproxy) isn’t 
appropriate for service providers in that users would have to pay for the extra 
load-balancer even though it is not being actively used.
One important idea of the HA is that its implementation is vendor-specific, so 
each vendor or cloud provider can implement it in the way that suits their 
needs. So I don't see why particular HA solution for haproxy should be 
considered as a common among other vendors/providers.

[Susanne] Are you saying that we should create a driver that would be a peer to 
the current loadbalancer/ ha-proxy driver? So for example  
loadbalancer/managed-ha-proxy (please don’t get hung-up on the name I picked) 
would be a driver we would implement to get our interaction with a pool of 
stand-by load-and preconfigured load balancers instead of the 2 LB HA servers? 
And it would be part of the Neutron LBaaS branch?

I am assuming that blueprints need to be approved before the feature is 
accepted into a release. Then the feature is implemented and accepted by the 
core members into the main repo. What the process would we have to follow if we 
wanted to get such a driver into Neutron LBaaS? It is hard to imagine that even 
thought it would be a “vendor-specific ha-proxy” driver that people in the 
Neutron LBaaS team wouldn't want to have a say around how it is architected.


An alternative approach is to implement resiliency using a pool of stand-by 
load-and preconfigured load balancers own by e.g. LBaaS tenant and assign 
load-balancers from the pool to tenants environments. We currently are using 
this approach in the public cloud with Libra and it takes approximately 80 
seconds for the service to decide that a load-balancer has failed, swap the 
floating ip and update the db, etc. and have a new LB running.

That for sure can be implemented. I only would recommend to implement such kind 
of management system out of Neutron/LBaaS tree, e.g. to only have client within 
Libra driver that will communicate with the management backend.

[Susanne] Again this would only be a short term solution since as we move 
forward and want to contribute new features it would result in duplication of 
efforts because the features might need to be done in Libra and not Neutron 
LBaaS.

In the longer term I would like to discuss how we make Neutron LBaaS have 
features that are a little friendlier towards service providers' use cases. It 
is very important to us that services like the LBaaS service is viewed as a 
managed service e.g. black-box to our customers.



Thanks,
Eugene.


Regards Susanne
-------------------------------------------
Susanne M. Balle
Hewlett-Packard
HP Cloud Services
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