Open Stack

On 2/14/15 9:49 PM, Adam Young wrote:
> On 02/13/2015 04:19 PM, Morgan Fainberg wrote:
>> On February 13, 2015 at 11:51:10 AM, Lance Bragstad
>> (lbragstad at gmail.com <mailto:lbragstad at gmail.com>) wrote:
>>> Hello all,
>>>
>>>
>>> I'm proposing the Authenticated Encryption (AE) Token specification
>>> [1] as an SPFE. AE tokens increases scalability of Keystone by
>>> removing token persistence. This provider has been discussed prior
>>> to, and at the Paris summit [2]. There is an implementation that is
>>> currently up for review [3], that was built off a POC. Based on the
>>> POC, there has been some performance analysis done with respect to
>>> the token formats available in Keystone (UUID, PKI, PKIZ, AE) [4].
>>>
>>> The Keystone team spent some time discussing limitations of the
>>> current POC implementation at the mid-cycle. One case that still
>>> needs to be addressed (and is currently being worked), is federated
>>> tokens. When requesting unscoped federated tokens, the token contains
>>> unbound groups which would need to be carried in the token. This case
>>> can be handled by AE tokens but it would be possible for an unscoped
>>> federated AE token to exceed an acceptable AE token length (i.e. <
>>> 255 characters). Long story short, a federation migration could be
>>> used to ensure federated AE tokens never exceed a certain length.
>>>
>>> Feel free to leave your comments on the AE Token spec.
>>>
>>> Thanks!
>>>
>>> Lance
>>>
>>> [1] https://review.openstack.org/#/c/130050/
>>> [2] https://etherpad.openstack.org/p/kilo-keystone-authorization
>>> [3] https://review.openstack.org/#/c/145317/
>>> [4] http://dolphm.com/benchmarking-openstack-keystone-token-formats/
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>>
>>
>> I am for granting this exception as long as it’s clear that the
>> following is clear/true:
>>
>> * All current use-cases for tokens (including federation) will be
>> supported by the new token provider.
>>
>> * The federation tokens being possibly over 255 characters can be
>> addressed in the future if they are not addressed here (a “federation
>> migration” does not clearly state what is meant.
>>
> I think the length of the token is not a real issue.  We need to keep
> them within header lengths.  That is 8k.  Anything smaller than that
> will work.

I'd like to respectfully disagree here. Large tokens can dramatically 
increase the overhead for users of Swift with small objects since the 
token must be passed along with every request.

For example, I have a small static web site: 68 files, mean file size 
5508 bytes, median 636 bytes, total 374517 bytes. (It's an actual site; 
these are genuine data.)

If I upload these things to Swift using a UUID token, then I incur maybe 
400 bytes of overhead per file in the HTTP request, which is a 7.3% 
bloat. On the other hand, if the token + other headers is 8K, then I'm 
looking at 149% bloat, so I've more than doubled my transfer 
requirements just from tokens. :/

I think that, for users of Swift and any other OpenStack data-plane 
APIs, token size is a definite concern. I am very much in favor of 
anything that shrinks token sizes while keeping the scalability benefits 
of PKI tokens.