Re: [openstack-dev] [magnum] Nesting /containers resource under /bays

[Kyle Kelley]

What are the reasons for keeping /containers?

On Fri, Jan 15, 2016 at 9:14 PM, Hongbin Lu <hongbin...@huawei.com> wrote:

> Disagree.
>
>
>
> If the container managing part is removed, Magnum is just a COE deployment
> tool. This is really a scope-mismatch IMO. The middle ground I can see is
> to have a flag that allows operators to turned off the container managing
> part. If it is turned off, COEs are not managed by Magnum and requests sent
> to the /container endpoint will return a reasonable error code. Thoughts?
>
>
>
> Best regards,
>
> Hongbin
>
>
>
> *From:* Mike Metral [mailto:mike.met...@rackspace.com]
> *Sent:* January-15-16 6:24 PM
> *To:* openstack-dev@lists.openstack.org
>
> *Subject:* Re: [openstack-dev] [magnum] Nesting /containers resource
> under /bays
>
>
>
> I too believe that the /containers endpoint is obstructive to the overall
> goal of Magnum.
>
>
>
> IMO, Magnum’s scope should *only* be concerned with:
>
>1. Provisioning the underlying infrastructure required by the
>Container Orchestration Engine (COE) and
>2. Instantiating the COE itself on top of said infrastructure from
>step #1.
>
> Anything further regarding Magnum interfacing or interacting with
> containers starts to get into a gray area that could easily evolve into:
>
>- Potential race conditions between Magnum and the designated COE and
>- Would create design & implementation overhead and debt that could
>bite us in the long run seeing how all COE’s operate & are based off
>various different paradigms in terms of describing & managing containers,
>and this divergence will only continue to grow with time.
>- Not to mention, the recreation of functionality around managing
>containers in Magnum seems redundant in nature as this is the very reason
>to want to use a COE in the first place – because it’s a more suited tool
>for the task
>
> If there is low-hanging fruit in terms of common functionality across
> *all* COE’s, then those generic capabilities *could* be abstracted and
> integrated into Magnum, but these have to be carefully examined beforehand
> to ensure true parity exists for the capability across all COE’s.
>
>
>
> However, I still worry that going down this route toes the line that
> Magnum should and could be a part of the managing container story to some
> degree – which again should be the sole responsibility of the COE, not
> Magnum.
>
>
>
> I’m in favor of doing away with the /containers endpoint – continuing with
> it just looks like a snowball of scope-mismatch and management issues just
> waiting to happen.
>
>
>
> Mike Metral
>
> Product Architect – Private Cloud R - Rackspace
> --
>
> *From:* Hongbin Lu <hongbin...@huawei.com>
> *Sent:* Thursday, January 14, 2016 1:59 PM
> *To:* OpenStack Development Mailing List (not for usage questions)
> *Subject:* Re: [openstack-dev] [magnum] Nesting /containers resource
> under /bays
>
>
>
> In short, the container IDs assigned by Magnum are independent of the
> container IDs assigned by Docker daemon. Magnum do the IDs mapping before
> doing a native API call. In particular, here is how it works.
>
>
>
> If users create a container through Magnum endpoint, Magnum will do the
> followings:
>
> 1.   Generate a uuid (if not provided).
>
> 2.   Call Docker Swarm API to create a container, with its hostname
> equal to the generated uuid.
>
> 3.   Persist container to DB with the generated uuid.
>
>
>
> If users perform an operation on an existing container, they must provide
> the uuid (or the name) of the container (if name is provided, it will be
> used to lookup the uuid). Magnum will do the followings:
>
> 1.   Call Docker Swarm API to list all containers.
>
> 2.   Find the container whose hostname is equal to the provided uuid,
> record its “docker_id” that is the ID assigned by native tool.
>
> 3.   Call Docker Swarm API with “docker_id” to perform the operation.
>
>
>
> Magnum doesn’t assume all operations to be routed through Magnum
> endpoints. Alternatively, users can directly call the native APIs. In this
> case, the created resources are not managed by Magnum and won’t be
> accessible through Magnum’s endpoints.
>
>
>
> Hope it is clear.
>
>
>
> Best regards,
>
> Hongbin
>
>
>
> *From:* Kyle Kelley [mailto:kyle.kel...@rackspace.com
> <kyle.kel...@rackspace.com>]
> *Sent:* January-14-16 11:39 AM
> *To:* OpenStack Development Mailing List (not for usage questions)
> *Subject:* Re: [openstack-dev] [magnum] Ne

Re: [openstack-dev] [magnum] Nesting /containers resource under /bays

[Kyle Kelley]

When using the native Docker tooling, the Docker daemon controls the UUID of 
the container, not Magnum.

-- Kyle


From: Ryan Brown 
Sent: Wednesday, January 13, 2016 3:16 PM
To: openstack-dev@lists.openstack.org
Subject: Re: [openstack-dev] [magnum] Nesting /containers resource under
/bays

On 01/13/2016 04:42 AM, Jamie Hannaford wrote:
> I've recently been gathering feedback about the Magnum API and one of
> the things that people commented on​ was the global /containers
> endpoints. One person highlighted the danger of UUID collisions:
>
>
> """
>
> It takes a container ID which is intended to be unique within that
> individual cluster. Perhaps this doesn't matter, considering the surface
> for hash collisions. You're running a 1% risk of collision on the
> shorthand container IDs:
>
>
> In [14]: n = lambda p,H: math.sqrt(2*H * math.log(1/(1-p)))
>
> In [15]: n(.01, 0x1)
> Out[15]: 2378620.6298183016
>
>
> (this comes from the Birthday Attack -
> https://en.wikipedia.org/wiki/Birthday_attack)
> 
>
>
> The main reason I questioned this is that we're not in control of how
> the hashes are created whereas each Docker node or Swarm cluster will
> pick a new ID under collisions. We don't have that guarantee when
> aggregating across.
>
>
> The use case that was outlined appears to be aggregation and reporting.
> That can be done in a different manner than programmatic access to
> single containers.​
>
> """
>
>
> Representing a resource without reference to its parent resource also
> goes against the convention of many other OpenStack APIs.
>
>
> Nesting a container resource under its parent bay would mitigate both of
> these issues:
>
>
> /bays/{uuid}/containers/{uuid}​
>
>
> I'd like to get feedback from folks in the Magnum team and see if
> anybody has differing opinions about this.
>
>
> Jamie

I'm not a member of the Magnum community, but I am on the API working
group, so my opinions come from a slightly different perspective.

Nesting resources is not a "bad" thing, and as long as containers will
always be in bays (from what I understand of the Magnum architecture,
this is indeed true) then nesting them makes sense.

Of course, it's a big change and will have to be communicated to users &
client libraries, probably via a version bump.

--
Ryan Brown / Senior Software Engineer, Openstack / Red Hat, Inc.

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Re: [openstack-dev] [magnum] Nesting /containers resource under /bays

[Kyle Kelley]

This presumes a model where Magnum is in complete control of the IDs of 
individual containers. How does this work with the Docker daemon?


> In Rest API, you can set the “uuid” field in the json request body (this is 
> not supported in CLI, but it is an easy add).​


In the Rest API for Magnum or Docker? Has Magnum completely broken away from 
exposing native tooling - are all container operations assumed to be routed 
through Magnum endpoints?


> For the idea of nesting container resource, I prefer not to do that if there 
> are alternatives or it can be work around. IMO, it sets a limitation that a 
> container must have a bay, which might not be the case in future. For 
> example, we might add a feature that creating a container will automatically 
> create a bay. If a container must have a bay on creation, such feature is 
> impossible.


If that's *really* a feature you need and are fully involved in designing for, 
this seems like a case where creating a container via these endpoints would 
create a bay and return the full resource+subresource.


Personally, I think these COE endpoints need to not be in the main spec, to 
reduce the surface area until these are put into further use.





From: Hongbin Lu 
Sent: Wednesday, January 13, 2016 5:00 PM
To: OpenStack Development Mailing List (not for usage questions)
Subject: Re: [openstack-dev] [magnum] Nesting /containers resource under /bays

Hi Jamie,

I would like to clarify several things.

First, a container uuid is intended to be unique globally (not within 
individual cluster). If you create a container with duplicated uuid, the 
creation will fail regardless of its bay. Second, you are in control of the 
uuid of the container that you are going to create. In Rest API, you can set 
the “uuid” field in the json request body (this is not supported in CLI, but it 
is an easy add). If a uuid is provided, Magnum will use it as the uuid of the 
container (instead of generating a new uuid).

For the idea of nesting container resource, I prefer not to do that if there 
are alternatives or it can be work around. IMO, it sets a limitation that a 
container must have a bay, which might not be the case in future. For example, 
we might add a feature that creating a container will automatically create a 
bay. If a container must have a bay on creation, such feature is impossible.

Best regards,
Hongbin

From: Jamie Hannaford [mailto:jamie.hannaf...@rackspace.com]
Sent: January-13-16 4:43 AM
To: openstack-dev@lists.openstack.org
Subject: [openstack-dev] [magnum] Nesting /containers resource under /bays


I've recently been gathering feedback about the Magnum API and one of the 
things that people commented on​ was the global /containers endpoints. One 
person highlighted the danger of UUID collisions:



"""

It takes a container ID which is intended to be unique within that individual 
cluster. Perhaps this doesn't matter, considering the surface for hash 
collisions. You're running a 1% risk of collision on the shorthand container 
IDs:



In [14]: n = lambda p,H: math.sqrt(2*H * math.log(1/(1-p)))
In [15]: n(.01, 0x1)
Out[15]: 2378620.6298183016



(this comes from the Birthday Attack - 
https://en.wikipedia.org/wiki/Birthday_attack)



The main reason I questioned this is that we're not in control of how the 
hashes are created whereas each Docker node or Swarm cluster will pick a new ID 
under collisions. We don't have that guarantee when aggregating across.



The use case that was outlined appears to be aggregation and reporting. That 
can be done in a different manner than programmatic access to single 
containers.​

"""



Representing a resource without reference to its parent resource also goes 
against the convention of many other OpenStack APIs.



Nesting a container resource under its parent bay would mitigate both of these 
issues:



/bays/{uuid}/containers/{uuid}​



I'd like to get feedback from folks in the Magnum team and see if anybody has 
differing opinions about this.



Jamie






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Re: [openstack-dev] [magnum] Nesting /containers resource under /bays

[Kyle Kelley]

With /containers gone, what Magnum offers is a workflow for consuming container 
orchestration engines:

* Deployment of a cluster
* Management of that cluster
* Key handling (creation, upload, revocation, etc.)

The first two are handled underneath by Nova + Heat, the last is in the purview 
of Barbican. That doesn't matter though.

What users care about is getting access to these resources without having to 
write their own heat template, create a backing key store, etc. They'd like to 
get started immediately with container technologies that are proven.

If you're looking for analogies Hongbin, this would be more like saying that 
Cinder shouldn't have an endpoint that let you work with individual files on a 
volume. It would be unreasonable to try to abstract across filesystems in a 
meaningful and sustainable way.


From: Hongbin Lu <hongbin...@huawei.com>
Sent: Tuesday, January 19, 2016 9:43 AM
To: OpenStack Development Mailing List (not for usage questions)
Subject: Re: [openstack-dev] [magnum] Nesting /containers resource under /bays

Assume your logic is applied. Should Nova remove the endpoint of managing VMs? 
Should Cinder remove the endpoint of managing volumes?

I think the best way to deal with the heterogeneity is to introduce a common 
abstraction layer, not to decouple from it. The real critical functionality 
Magnum could offer to OpenStack is to provide a Container-as-a-Service. If 
Magnum is a Deployment-as-a-service, it will be less useful and won't bring too 
much value to the OpenStack ecosystem.

Best regards,
Hongbin

-Original Message-
From: Clark, Robert Graham [mailto:robert.cl...@hpe.com]
Sent: January-19-16 5:19 AM
To: OpenStack Development Mailing List (not for usage questions)
Subject: Re: [openstack-dev] [magnum] Nesting /containers resource under /bays

+1

Doing this, and doing this well, provides critical functionality to OpenStack 
while keeping said functionality reasonably decoupled from the COE API vagaries 
that would inevitably encumber a solution that sought to provide ‘one api to 
control them all’.

-Rob

From: Mike Metral
Reply-To: OpenStack List
Date: Saturday, 16 January 2016 02:24
To: OpenStack List
Subject: Re: [openstack-dev] [magnum] Nesting /containers resource under /bays

The requirements that running a fully containerized application optimally & 
effectively requires the usage of a dedicated COE tool such as Swarm, 
Kubernetes or Marathon+Mesos.

OpenStack is better suited for managing the underlying infrastructure.

Mike Metral
Product Architect – Private Cloud R
email: mike.met...@rackspace.com<mailto:mike.met...@rackspace.com>
cell: +1-<tel:%2B1-305-282-7606>305-282-7606<tel:%2B1-305-282-7606>

From: Hongbin Lu
Reply-To: "OpenStack Development Mailing List (not for usage questions)"
Date: Friday, January 15, 2016 at 8:02 PM
To: "OpenStack Development Mailing List (not for usage questions)"
Subject: Re: [openstack-dev] [magnum] Nesting /containers resource under /bays

A reason is the container abstraction brings containers to OpenStack: Keystone 
for authentication, Heat for orchestration, Horizon for UI, etc.

From: Kyle Kelley [mailto:rgb...@gmail.com]
Sent: January-15-16 10:42 PM
To: OpenStack Development Mailing List (not for usage questions)
Subject: Re: [openstack-dev] [magnum] Nesting /containers resource under /bays

What are the reasons for keeping /containers?

On Fri, Jan 15, 2016 at 9:14 PM, Hongbin Lu 
<hongbin...@huawei.com<mailto:hongbin...@huawei.com>> wrote:
Disagree.

If the container managing part is removed, Magnum is just a COE deployment 
tool. This is really a scope-mismatch IMO. The middle ground I can see is to 
have a flag that allows operators to turned off the container managing part. If 
it is turned off, COEs are not managed by Magnum and requests sent to the 
/container endpoint will return a reasonable error code. Thoughts?

Best regards,
Hongbin

From: Mike Metral 
[mailto:mike.met...@rackspace.com<mailto:mike.met...@rackspace.com>]
Sent: January-15-16 6:24 PM
To: openstack-dev@lists.openstack.org<mailto:openstack-dev@lists.openstack.org>

Subject: Re: [openstack-dev] [magnum] Nesting /containers resource under /bays

I too believe that the /containers endpoint is obstructive to the overall goal 
of Magnum.

IMO, Magnum’s scope should only be concerned with:

  1.  Provisioning the underlying infrastructure required by the Container 
Orchestration Engine (COE) and
  2.  Instantiating the COE itself on top of said infrastructure from step #1.
Anything further regarding Magnum interfacing or interacting with containers 
starts to get into a gray area that could easily evolve into:

  *   Potential race conditions between Magnum and the designated COE and
  *   Would create design & implementation overhead and debt that could bite us 
in the long run seeing how all COE’s operate & are bas