[openstack-dev] [magnum] Discussion of supporting single/multiple OS distro

Cammann, Tom tom.cammann at hpe.com
Mon Feb 29 17:01:13 UTC 2016

One of the main reasons for moving to a "bay driver” model was to allow us to
focus our efforts. We talked about focusing our support to the distros with a
religion around them, e.g. Ubuntu and a Red Hat derivative.

Being frank, I do not see much benefit in supporting a small distro if we have
support for a big one. We have seen the templates for these various distros
languish in the past and become quickly outdated. I would much rather have a
concerted effort around a single distro.

The way we could support multiple distros in Magnum would be to create a new
“bay driver” for that distro+template+template_definition. This set of items
would be self contained and would not interact with another bay driver that
used that same COE. This will allow that bay driver to move at the pace of the
team working on it and explicitly list out the features supported by this bay
driver. As it currently stands it is difficult to understand the parity between
two distros using the same COE.

I raised the concern that this could lead to a duplication of code, but we felt
that this refactor had more benefits and we could easily work around this


From: Hongbin Lu <hongbin.lu at huawei.com<mailto:hongbin.lu at huawei.com>>
Reply-To: "OpenStack Development Mailing List (not for usage questions)" <openstack-dev at lists.openstack.org<mailto:openstack-dev at lists.openstack.org>>
Date: Monday, 29 February 2016 at 16:40
To: "openstack-dev at lists.openstack.org<mailto:openstack-dev at lists.openstack.org>" <openstack-dev at lists.openstack.org<mailto:openstack-dev at lists.openstack.org>>
Subject: [openstack-dev] [magnum] Discussion of supporting single/multiple OS distro

Hi team,

This is a continued discussion from a review [1]. Corey O'Brien suggested to have Magnum support a single OS distro (Atomic). I disagreed. I think we should bring the discussion to here to get broader set of inputs.

Corey O'Brien
From the midcycle, we decided we weren't going to continue to support 2 different versions of the k8s template. Instead, we were going to maintain the Fedora Atomic version of k8s and remove the coreos templates from the tree. I don't think we should continue to develop features for coreos k8s if that is true.
In addition, I don't think we should break the coreos template by adding the trust token as a heat parameter.

Hongbin Lu
I was on the midcycle and I don't remember any decision to remove CoreOS support. Why you want to remove CoreOS templates from the tree. Please note that this is a very big decision and please discuss it with the team thoughtfully and make sure everyone agree.

Corey O'Brien
Removing the coreos templates was a part of the COE drivers decision. Since each COE driver will only support 1 distro+version+coe we discussed which ones to support in tree. The decision was that instead of trying to support every distro and every version for every coe, the magnum tree would only have support for 1 version of 1 distro for each of the 3 COEs (swarm/docker/mesos). Since we already are going to support Atomic for swarm, removing coreos and keeping Atomic for kubernetes was the favored choice.

Hongbin Lu
Strongly disagree. It is a huge risk to support a single distro. The selected distro could die in the future. Who knows. Why make Magnum take this huge risk? Again, the decision of supporting single distro is a very big decision. Please bring it up to the team and have it discuss thoughtfully before making any decision. Also, Magnum doesn't have to support every distro and every version for every coe, but should support *more than one* popular distro for some COEs (especially for the popular COEs).

Corey O'Brien
The discussion at the midcycle started from the idea of adding support for RHEL and CentOS. We all discussed and decided that we wouldn't try to support everything in tree. Magnum would provide support in-tree for 1 per COE and the COE driver interface would allow others to add support for their preferred distro out of tree.

Hongbin Lu
I agreed the part that "we wouldn't try to support everything in tree". That doesn't imply the decision to support single distro. Again, support single distro is a huge risk. Why make Magnum take this huge risk?

[1] https://review.openstack.org/#/c/277284/

Best regards,

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