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Dmitriy,

New tests, that cover new functionality already know which API version they
require. So, even in testing, it is not needed. All other existing tests do
not require API update.

So, I raise hand for restricting "latest".

On Fri, Aug 28, 2015 at 10:20 AM, Dmitry Tantsur <dtantsur at redhat.com>
wrote:

> On 08/27/2015 09:38 PM, Ben Swartzlander wrote:
>
>> Manila recently implemented microversions, copying the implementation
>> from Nova. I really like the feature! However I noticed that it's legal
>> for clients to transmit "latest" instead of a real version number.
>>
>> THIS IS A TERRIBLE IDEA!
>>
>> I recommend removing support for "latest" and forcing clients to request
>> a specific version (or accept the default).
>>
>
> I think "latest" is needed for integration testing. Otherwise you have to
> update your tests each time new version is introduced.
>
>
>
>> Allowing clients to request the "latest" microversion guarantees
>> undefined (and likely broken) behavior* in every situation where a
>> client talks to a server that is newer than it.
>>
>> Every client can only understand past and present API implementation,
>> not future implementations. Transmitting "latest" implies an assumption
>> that the future is not so different from the present. This assumption
>> about future behavior is precisely what we don't want clients to make,
>> because it prevents forward progress. One of the main reasons
>> microversions is a valuable feature is because it allows forward
>> progress by letting us make major changes without breaking old clients.
>>
>> If clients are allowed to assume that nothing will change too much in
>> the future (which is what asking for "latest" implies) then the server
>> will be right back in the situation it was trying to get out of -- it
>> can never change any API in a way that might break old clients.
>>
>> I can think of no situation where transmitting "latest" is better than
>> transmitting the highest version that existed at the time the client was
>> written.
>>
>> -Ben Swartzlander
>>
>> * Undefined/broken behavior unless the server restricts itself to never
>> making any backward-compatiblity-breaking change of any kind.
>>
>>
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>
>
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-- 
Kind Regards
Valeriy Ponomaryov
www.mirantis.com
vponomaryov at mirantis.com
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