Open Stack

Excerpts from Mike Spreitzer's message of 2014-07-16 10:50:42 -0700:
> Clint Byrum <clint at fewbar.com> wrote on 07/02/2014 01:54:49 PM:
> 
> > Excerpts from Qiming Teng's message of 2014-07-02 00:02:14 -0700:
> > > Just some random thoughts below ...
> > > 
> > > On Tue, Jul 01, 2014 at 03:47:03PM -0400, Mike Spreitzer wrote:
> > > > In AWS, an autoscaling group includes health maintenance 
> > functionality --- 
> > > > both an ability to detect basic forms of failures and an abilityto 
> react 
> > > > properly to failures detected by itself or by a load balancer.  What 
> is 
> > > > the thinking about how to get this functionality in OpenStack? Since 
> 
> > > 
> > > We are prototyping a solution to this problem at IBM Research - China
> > > lab.  The idea is to leverage oslo.messaging and ceilometer events for
> > > instance (possibly other resource such as port, securitygroup ...)
> > > failure detection and handling.
> > > 
> > 
> > Hm.. perhaps you should be contributing some reviews here as you may
> > have some real insight:
> > 
> > https://review.openstack.org/#/c/100012/
> > 
> > This sounds a lot like what we're working on for continuous convergence.
> 
> I noticed that health checking in AWS goes beyond convergence.  In AWS an 
> ELB can be configured with a URL to ping, for application-level health 
> checking.  And an ASG can simply be *told* the health of a member by a 
> user's own external health system.  I think we should have analogous 
> functionality in OpenStack.  Does that make sense to you?  If so, do you 
> have any opinion on the right way to integrate, so that we do not have 
> three completely independent health maintenance systems?

The check url is already a part of Neutron LBaaS IIRC. What may not be
a part is notifications for when all members are reporting down (which
might be something to trigger scale-up).

If we don't have push checks in our auto scaling implementation then we
don't have a proper auto scaling implementation.