[openstack-dev] [TripleO][Heat][Kolla][Magnum] The zen of Heat, containers, and the future of TripleO

Dan Prince dprince at redhat.com
Mon Mar 28 19:07:22 UTC 2016

On Wed, 2016-03-23 at 07:54 -0400, Ryan Hallisey wrote:
> *Snip*
> > 
> > Indeed, this has literally none of the benefits of the ideal Heat 
> > deployment enumerated above save one: it may be entirely the wrong
> > tool 
> > in every way for the job it's being asked to do, but at least it
> > is 
> > still well-integrated with the rest of the infrastructure.
> > 
> > Now, at the Mitaka summit we discussed the idea of a 'split
> > stack', 
> > where we have one stack for the infrastructure and a separate one
> > for 
> > the software deployments, so that there is no longer any tight 
> > integration between infrastructure and software. Although it makes
> > me a 
> > bit sad in some ways, I can certainly appreciate the merits of the
> > idea 
> > as well. However, from the argument above we can deduce that if
> > this is 
> > the *only* thing we do then we will end up in the very worst of
> > all 
> > possible worlds: the wrong tool for the job, poorly integrated.
> > Every 
> > single advantage of using Heat to deploy software will have
> > evaporated, 
> > leaving only disadvantages.
> I think Heat is a very powerful tool having done the container
> integration
> into the tripleo-heat-templates I can see its appeal.  Something I
> learned
> from integration, was that Heat is not the best tool for container
> deployment,
> at least right now.  We were able to leverage the work in Kolla, but
> what it
> came down to was that we're not using containers or Kolla to its max
> potential.
> I did an evaluation recently of tripleo and kolla to see what we
> would gain
> if the two were to combine. Let's look at some items on tripleo's
> roadmap.
> Split stack, as mentioned above, would be gained if tripleo were to
> adopt
> Kolla.  Tripleo holds the undercloud and ironic.  Kolla separates
> config
> and deployment.  Therefore, allowing for the decoupling for each
> piece of
> the stack.  Composable roles, this would be the ability to land
> services
> onto separate hosts on demand.  Kolla also already does this [1].
> Finally,
> container integration, this is just a given :).
> In the near term, if tripleo were to adopt Kolla as its overcloud it
> would
> be provided these features and retire heat to setting up the
> baremetal nodes
> and providing those ips to ansible.  This would be great for kolla
> too because
> it would provide baremetal provisioning.
> Ian Main and I are currently working on a POC for this as of last
> week [2].
> It's just a simple heat template :).
> I think further down the road we can evaluate using kubernetes [3].
> For now though,  kolla-anisble is rock solid and is worth using for
> the
> overcloud.

Yeah, well TripleO heat Overclouds are rock solid too. They just aren't
using containers everywhere yet. So lets fix that.

I'm not a fan of replacing the TripleO overcloud configuration with
Kolla. I don't think there is feature parity, the architectures are
different (HA, etc.) and I don't think you could easily pull off an
upgrade from one deployment to the other (going from TripleO Heat
template deployed overcloud to Kolla deployed overcloud).

> Thanks!
> -Ryan
> [1] - https://github.com/openstack/kolla/blob/master/ansible/inventor
> y/multinode
> [2] - https://github.com/rthallisey/kolla-heat-templates
> [3] - https://review.openstack.org/#/c/255450/
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