[openstack-dev] [TripleO] podman: varlink interface for nice API calls

Steve Baker sbaker at redhat.com
Mon Aug 27 02:01:46 UTC 2018



On 24/08/18 04:36, Fox, Kevin M wrote:
> Or use kubelet in standalone mode. It can be configured for either Cri-o or Docker. You can drive the static manifests from heat/ansible per host as normal and it would be a step in the greater direction of getting to Kubernetes without needing the whole thing at once, if that is the goal.

I was an advocate for using kubectl standalone for our container 
orchestration needs well before we started containerizing TripleO. After 
talking to a few kubernetes folk I cooled on the idea, because they had 
one of two responses:
- cautious encouragement, but uncertainty about kubectl standalone 
interface support and consideration for those use cases
- googly eyed incomprehension followed by "why would you do that??"

This was a while ago now so this could be worth revisiting in the 
future. We'll be making gradual changes, the first of which is using 
podman to manage single containers. However podman has native support 
for the pod format, so I'm hoping we can switch to that once this 
transition is complete. Then evaluating kubectl becomes much easier.

>
> Question. Rather then writing a middle layer to abstract both container engines, couldn't you just use CRI? CRI is CRI-O's native language, and there is support already for Docker as well.

We're not writing a middle layer, we're leveraging one which is already 
there.

CRI-O is a socket interface and podman is a CLI interface that both sit 
on top of the exact same Go libraries. At this point, switching to 
podman needs a much lower development effort because we're replacing 
docker CLI calls.
> Thanks,
> Kevin
> ________________________________________
> From: Jay Pipes [jaypipes at gmail.com]
> Sent: Thursday, August 23, 2018 8:36 AM
> To: openstack-dev at lists.openstack.org
> Subject: Re: [openstack-dev] [TripleO] podman: varlink interface for nice API calls
>
> Dan, thanks for the details and answers. Appreciated.
>
> Best,
> -jay
>
> On 08/23/2018 10:50 AM, Dan Prince wrote:
>> On Wed, Aug 15, 2018 at 5:49 PM Jay Pipes <jaypipes at gmail.com> wrote:
>>> On 08/15/2018 04:01 PM, Emilien Macchi wrote:
>>>> On Wed, Aug 15, 2018 at 5:31 PM Emilien Macchi <emilien at redhat.com
>>>> <mailto:emilien at redhat.com>> wrote:
>>>>
>>>>       More seriously here: there is an ongoing effort to converge the
>>>>       tools around containerization within Red Hat, and we, TripleO are
>>>>       interested to continue the containerization of our services (which
>>>>       was initially done with Docker & Docker-Distribution).
>>>>       We're looking at how these containers could be managed by k8s one
>>>>       day but way before that we plan to swap out Docker and join CRI-O
>>>>       efforts, which seem to be using Podman + Buildah (among other things).
>>>>
>>>> I guess my wording wasn't the best but Alex explained way better here:
>>>> http://eavesdrop.openstack.org/irclogs/%23openstack-tc/%23openstack-tc.2018-08-15.log.html#t2018-08-15T17:56:52
>>>>
>>>> If I may have a chance to rephrase, I guess our current intention is to
>>>> continue our containerization and investigate how we can improve our
>>>> tooling to better orchestrate the containers.
>>>> We have a nice interface (openstack/paunch) that allows us to run
>>>> multiple container backends, and we're currently looking outside of
>>>> Docker to see how we could solve our current challenges with the new tools.
>>>> We're looking at CRI-O because it happens to be a project with a great
>>>> community, focusing on some problems that we, TripleO have been facing
>>>> since we containerized our services.
>>>>
>>>> We're doing all of this in the open, so feel free to ask any question.
>>> I appreciate your response, Emilien, thank you. Alex' responses to
>>> Jeremy on the #openstack-tc channel were informative, thank you Alex.
>>>
>>> For now, it *seems* to me that all of the chosen tooling is very Red Hat
>>> centric. Which makes sense to me, considering Triple-O is a Red Hat product.
>> Perhaps a slight clarification here is needed. "Director" is a Red Hat
>> product. TripleO is an upstream project that is now largely driven by
>> Red Hat and is today marked as single vendor. We welcome others to
>> contribute to the project upstream just like anybody else.
>>
>> And for those who don't know the history the TripleO project was once
>> multi-vendor as well. So a lot of the abstractions we have in place
>> could easily be extended to support distro specific implementation
>> details. (Kind of what I view podman as in the scope of this thread).
>>
>>> I don't know how much of the current reinvention of container runtimes
>>> and various tooling around containers is the result of politics. I don't
>>> know how much is the result of certain companies wanting to "own" the
>>> container stack from top to bottom. Or how much is a result of technical
>>> disagreements that simply cannot (or will not) be resolved among
>>> contributors in the container development ecosystem.
>>>
>>> Or is it some combination of the above? I don't know.
>>>
>>> What I *do* know is that the current "NIH du jour" mentality currently
>>> playing itself out in the container ecosystem -- reminding me very much
>>> of the Javascript ecosystem -- makes it difficult for any potential
>>> *consumers* of container libraries, runtimes or applications to be
>>> confident that any choice they make towards one of the other will be the
>>> *right* choice or even a *possible* choice next year -- or next week.
>>> Perhaps this is why things like openstack/paunch exist -- to give you
>>> options if something doesn't pan out.
>> This is exactly why paunch exists.
>>
>> Re, the podman thing I look at it as an implementation detail. The
>> good news is that given it is almost a parity replacement for what we
>> already use we'll still contribute to the OpenStack community in
>> similar ways. Ultimately whether you run 'docker run' or 'podman run'
>> you end up with the same thing as far as the existing TripleO
>> architecture goes.
>>
>> Dan
>>
>>> You have a tough job. I wish you all the luck in the world in making
>>> these decisions and hope politics and internal corporate management
>>> decisions play as little a role in them as possible.
>>>
>>> Best,
>>> -jay
>>>
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