Open Stack

On 11/04/2015 09:32 AM, Sean Dague wrote:
> On 11/04/2015 09:00 AM, Jay Pipes wrote:
>> On 11/03/2015 05:20 PM, Boris Pavlovic wrote:
>>> Hi stackers,
>>>
>>> Usually such projects like Heat, Tempest, Rally, Scalar, and other tool
>>> that works with OpenStack are working with resources (e.g. VM, Volumes,
>>> Images, ..) in the next way:
>>>
>>>   >>> resource = api.resouce_do_some_stuff()
>>>   >>> while api.resource_get(resource["uuid"]) != expected_status
>>>   >>>    sleep(a_bit)
>>>
>>> For each async operation they are polling and call many times
>>> resource_get() which creates significant load on API and DB layers due
>>> the nature of this request. (Usually getting full information about
>>> resources produces SQL requests that contains multiple JOINs, e,g for
>>> nova vm it's 6 joins).
>>>
>>> What if we add new API method that will just resturn resource status by
>>> UUID? Or even just extend get request with the new argument that returns
>>> only status?
>>
>> +1
>>
>> All APIs should have an HTTP HEAD call on important resources for
>> retrieving quick status information for the resource.
>>
>> In fact, I proposed exactly this in my Compute "vNext" API proposal:
>>
>> http://docs.oscomputevnext.apiary.io/#reference/server/serversid/head
>>
>> Swift's API supports HEAD for accounts:
>>
>> http://developer.openstack.org/api-ref-objectstorage-v1.html#showAccountMeta
>>
>>
>> containers:
>>
>> http://developer.openstack.org/api-ref-objectstorage-v1.html#showContainerMeta
>>
>>
>> and objects:
>>
>> http://developer.openstack.org/api-ref-objectstorage-v1.html#showObjectMeta
>>
>> So, yeah, I agree.
>> -jay
>
> How would you expect this to work on "servers"? HEAD specifically
> forbids returning a body, and, unlike swift, we don't return very much
> information in our headers.

I didn't propose doing it on a collection resource like "servers". Only 
on an entity resource like a single "server".

HEAD /v2/{tenant}/servers/{uuid}
HTTP/1.1 200 OK
Content-Length: 1022
Last-Modified: Thu, 16 Jan 2014 21:12:31 GMT
Content-Type: application/json
Date: Thu, 16 Jan 2014 21:13:19 GMT
OpenStack-Compute-API-Server-VM-State: ACTIVE
OpenStack-Compute-API-Server-Power-State: RUNNING
OpenStack-Compute-API-Server-Task-State: NONE

Best,
-jay