[openstack-dev] Is the pendulum swinging on PaaS layers?

Sean Dague sean at dague.net
Fri May 19 13:18:16 UTC 2017

On 05/19/2017 09:04 AM, Chris Dent wrote:
> On Fri, 19 May 2017, Duncan Thomas wrote:
>> On 19 May 2017 at 12:24, Sean Dague <sean at dague.net> wrote:
>>> I do get the concerns of extra logic in Nova, but the decision to break
>>> up the working compute with network and storage problem space across 3
>>> services and APIs doesn't mean we shouldn't still make it easy to
>>> express some pretty basic and common intents.
>> Given that we've similar needs for retries and race avoidance in and
>> between glance, nova, cinder and neutron, and a need or orchestrate
>> between at least these three (arguably other infrastructure projects
>> too, I'm not trying to get into specifics), maybe the answer is to put
>> that logic in a new service, that talks to those four, and provides a
>> nice simple API, while allowing the cinder, nova etc APIs to remove
>> things like internal retries?
> This is what enamel was going to be, but we got stalled out because
> of lack of resources and the usual raft of other commitments:
>     https://github.com/jaypipes/enamel

There was a conversation in the Cell v2 discussion around searchlight
that puts me more firmly in the anti enamel camp. Because of some
complexities around server list, Nova was planning on using Searchlight
to provide an efficient backend.

Q: Who in this room is running ELK already in their environment?
A: 100% of operators in room

Q: Who would be ok with standing up Searchlight for this?
A: 0% of operators in the room

We've now got an ecosystem that understands how to talk to our APIs
(yay! -
so saying "you need to also run this other service to *actually* do the
thing you want, and redo all your applications, and 3rd party SDKs" is
just weird.

And, yes, this is definitely a slider, and no I don't want Instance HA
in Nova. But we felt that "get-me-a-network" was important enough a user
experience to bake that in and stop poking users with sticks. And trying
hard to complete an expressed intent "POST /server" seems like it falls
on the line. Especially if the user received a conditional success (202).


Sean Dague

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