[openstack-dev] [zun] Some general ZUN use case / drivers type questions

Waines, Greg Greg.Waines at windriver.com
Fri Jul 7 11:04:55 UTC 2017

Thanks for the responses.
A couple of follow up, clarifying questions ...

·         You mentioned that currently Zun supports the container-in-baremetal scenario

o    is this done by leveraging Ironic baremetal service ?

§  e.g. does Zun launch an Ironic baremetal instance (running docker) in order to host containers being launched by Zun ?

o    OR

o    do you must mean that, in this scenario, OpenStack Hosts are deployed&configured with docker software,
and Zun expects docker to be running on each OpenStack Host, in order to launch its containers ?

·         In the future, when Zun supports the container-in-coe scenario

o    is the idea that the COE (Kubernetes or Swarm) will abstract from Zun whether the COE’s minion nodes are OpenStack VMs or OpenStack Baremetal Instances (or OpenStack Hosts) ?

o    is the idea that Magnum will support launching COEs with VM minion nodes and/or Baremetal minion nodes ?


From: Hongbin Lu <hongbin.lu at huawei.com>
Reply-To: "openstack-dev at lists.openstack.org" <openstack-dev at lists.openstack.org>
Date: Thursday, July 6, 2017 at 2:39 PM
To: "openstack-dev at lists.openstack.org" <openstack-dev at lists.openstack.org>
Subject: Re: [openstack-dev] [zun] Some general ZUN use case / drivers type questions

Hi Greg,

Please find my replies inline.

Best regards,

From: Waines, Greg [mailto:Greg.Waines at windriver.com]
Sent: July-06-17 11:49 AM
To: openstack-dev at lists.openstack.org
Subject: [openstack-dev] [zun] Some general ZUN use case / drivers type questions

Apologize I have some ‘newbie’ questions on zun.
I have looked a bit at zun ... a few slide decks and a few summit presentation videos.
I am somewhat familiar with old container orchestration attempts in openstack ... nova and heat.
And somewhat familiar with Magnum for COEs on VMs.

Question 1:

-          in long term, will ZUN manage containers hosted by OpenStack VMs or OpenStack Hosts or both ?

o    I think the answer is both, and

o    I think technically ZUN will manage the containers in OpenStack VM(s) or OpenStack Host(s), thru a COE

•  where the COE is kubernetes, swarm, mesos ... or, initially, some very simple default COE provided by ZUN itself.

[Hongbin Lu] Yes. Zun aims to support containers in VMs, baremetal, or COEs in long term. A clarification is Zun doesn’t aim to become a COE, but it could be used together with Heat [1] to achieve some container orchestration equivalent functionalities.

[1] https://review.openstack.org/#/c/437810/
Question 2:
-          what is currently supported in MASTER ?

[Hongbin Lu] What currently supported is container-in-baremetal scenario. The next release might introduce container-in-vm. COE integration might be the long term pursue.

Question 3:
-          in the scenario where ZUN is managing containers thru Kubernetes directly on OpenStack Host(s)
o    I believe the intent is that,
at the same time, and on the same OpenStack Host(s),
NOVA is managing VMs on the OpenStack Host(s)
o    ??? Has anyone started to look at the Resource Management / Arbitration of the OpenStack Host’s Resources,
       between ZUN and NOVA ???
[Hongbin Lu] No, it hasn’t. We started with an assumption that Zun and Nova are managing disjoined set of resources (i.e. compute hosts) so there is not resource contention. The ability to share compute resources across multiple OpenStack services for VMs and containers is cool and it might require discussions across multiple teams to build consensus of this pursue.
Question 4:
-          again, in the scenario where ZUN is managing containers thru Kubernetes directly on OpenStack Host(s)
-          what are the Technical Pros / Cons of this approach, relative to using OpenStack VM(s) ?
o    PROs
•  ??? does this really use less resources than the VM Scenario ???
•         is there an example you can walk me thru ?
•  I suppose that instead of pre-allocating resources to a fairly large VM for hosting containers,
you would only use the resources for the containers that are actually launched,
o    CONs
•  for application containers, you are restricted by the OS running on the OpenStack Host,

[Hongbin Lu] Yes, there are pros and cons of either approach, and Zun is not biased on either approach. Instead, Zun aims to support both if it is feasible.

Titanium Cloud
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