Open Stack

On 20/11/13 23:49, Christopher Armstrong wrote:
> On Wed, Nov 20, 2013 at 2:07 PM, Zane Bitter <zbitter at redhat.com
> <mailto:zbitter at redhat.com>> wrote:
>
>     On 20/11/13 16:07, Christopher Armstrong wrote:
>
>         On Tue, Nov 19, 2013 at 4:27 PM, Zane Bitter <zbitter at redhat.com
>         <mailto:zbitter at redhat.com>
>         <mailto:zbitter at redhat.com <mailto:zbitter at redhat.com>>> wrote:
>
>              On 19/11/13 19:14, Christopher Armstrong wrote:
>
>         thought we had a workable solution with the "LoadBalancerMember"
>         idea,
>         which you would use in a way somewhat similar to
>         CinderVolumeAttachment
>         in the above example, to hook servers up to load balancers.
>
>
>     I haven't seen this proposal at all. Do you have a link? How does it
>     handle the problem of wanting to notify an arbitrary service (i.e.
>     not necessarily a load balancer)?
>
>
> It's been described in the autoscaling wiki page for a while, and I
> thought the LBMember idea was discussed at the summit, but I wasn't
> there to verify that :)
>
> https://wiki.openstack.org/wiki/Heat/AutoScaling#LBMember.3F
>
> Basically, the LoadBalancerMember resource (which is very similar to the
> CinderVolumeAttachment) would be responsible for removing and adding IPs
> from/to the load balancer (which is actually a direct mapping to the way
> the various LB APIs work). Since this resource lives with the server
> resource inside the scaling unit, we don't really need to get anything
> _out_ of that stack, only pass _in_ the load balancer ID.

I see a couple of problems with this approach:

1) It makes the default case hard. There's no way to just specify a 
server and hook it up to a load balancer like you can at the moment. 
Instead, you _have_ to create a template (or template snippet - not 
really any better) to add this extra resource in, even for what should 
be the most basic, default case (scale servers behind a load balancer).

2) It relies on a plugin being present for any type of thing you might 
want to notify.

At summit and - to the best of my recollection - before, we talked about 
scaling a generic group of resources and passing notifications to a 
generic controller, with the types of both defined by the user. I was 
expecting you to propose something based on webhooks, which is why I was 
surprised not to see anything about it in the API. (I'm not prejudging 
that that is the way to go... I'm actually wondering if Marconi has a 
role to play here.)

cheers,
Zane.