Open Stack

On 05/21/2014 08:23 PM, John Dickinson wrote:
> On May 21, 2014, at 4:26 PM, Adam Young <ayoung at redhat.com> wrote:
>
>> On 05/21/2014 03:36 PM, Kurt Griffiths wrote:
>>> Good to know, thanks for clarifying. One thing I'm still fuzzy on, however, is why we want to deprecate use of UUID tokens in the first place? I'm just trying to understand the history here...
>> Because they are wasteful, and because they are the chattiest part of OpenStack.  I can go into it in nauseating detail if you really want, including the plans for future enhancements and the weaknesses of bearer tokens.
>>
>>
>> A token is nothing more than a snap shot of the data you get from Keystone distributed.  It is stored in Memcached and in the Horizon session uses the hash of it for a key.
>>
>> You can do the same thing.  Once you know the token has been transferred once to a service, assuming that service has caching on, you can pass the hash of the key instead of the whole thing.
> So this would mean that a Swift client would auth against Keystone to get the PKI token, send that to Swift, and then get back from Swift a "short" token that can be used for subsequent requests? It's an interesting idea to consider, but it is a new sort of protocol for clients to implement.
It would probably be more correct for Swift to calculate that, yes, but 
the client could also just calculate the hash and send it on subsequent 
requests.  As you pointed out, it is a matter of performance.


>
>
>> Actually, you can do that up front, as auth_token middleware will just default to an online lookup. However, we are planning on moving to ephemeral tokens (not saved in the database) and an online lookup won't be possible with those.  The people that manage Keystone will be happy with that, and forcing an online lookup will make them sad.
> An "online lookup" is one that calls the Keystone service to validate a token? Which implies that by disabling online lookup there is enough info in the token to validate it without any call to Keystone?
Yes.  the whole popen call to openssl to verify the messages.
>
> I understand how it's advantageous to offload token validation away from Keystone itself (helps with scaling), but the current "solution" here seems to be pushing a lot of pain to consumers and deployers of data APIs (eg Marconi and Swift and others).
We try to encapsulate it all within auth_token middleware, but the 
helper functions are in python-keystoneclient if you need more specific 
handling.

>
>
>> Hash is MD5 up through what is released in Icehouse.  The next version of auth_token middleware will support a configurable algorithm.  The default should be updated to sha256 in the near future.
> If a service (like Horizon) is hashing the token and using that as a session key, then why does it matter what the auth_token middleware supports? Isn't the hashing handled in the service itself? I'm thinking in the context of how we would implement this idea in Swift (exploring possibilities, not committing to a patch).
That is after it has received the token.  So, Horizon could send the 
hash to Nova, and Nova would then be required to make the call to 
Keystone, just like UUID tokens.  That would break on the ephemeral 
approach.

I'm exploring the Horizon side of the equasion for some other reasons, 
primarily in the context of Kerberos support, but also for better 
revocation rules.  If the onus is on the client (in this case Horizon) 
to remember if it has send a particular token in full form it might be a 
little hard to keep track.

What communication is most impacted by the large token size?  Is it 
fetching out images for a web page or something like that?


>
>>
>>
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>>
>>> From: Morgan Fainberg <morgan.fainberg at gmail.com>
>>> Reply-To: OpenStack Dev <openstack-dev at lists.openstack.org>
>>> Date: Wednesday, May 21, 2014 at 1:23 PM
>>> To: OpenStack Dev <openstack-dev at lists.openstack.org>
>>> Subject: Re: [openstack-dev] Concerns about the ballooning size of keystone tokens
>>>
>>> This is part of what I was referencing in regards to lightening the data stored in the token. Ideally, we would like to see an "ID only" token that only contains the basic information to act. Some initial tests show these tokens should be able to clock in under 1k in size. However all the details are not fully defined yet. Coupled with this data reduction there will be explicit definitions of the data that is meant to go into the tokens. Some of the data we have now is a result of convenience of accessing the data.
>>>
>>> I hope to have this token change available during Juno development cycle.
>>>
>>> There is a lot of work to be done to ensure this type of change goes smoothly. But this is absolutely on the list of things we would like to address.
>>>
>>> Cheers,
>>> Morgan
>>>
>>> Sent via mobile
>>>
>>> On Wednesday, May 21, 2014, Kurt Griffiths <kurt.griffiths at rackspace.com> wrote:
>>>> adding another ~10kB to each request, just to save a once-a-day call to
>>>> Keystone (ie uuid tokens) seems to be a really high price to pay for not
>>>> much benefit.
>>> I have the same concern with respect to Marconi. I feel like KPI tokens
>>> are fine for control plane APIs, but don't work so well for high-volume
>>> data APIs where every KB counts.
>>>
>>> Just my $0.02...
>>>
>>> --Kurt
>>>
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