[openstack-dev] [nova] how to handle vendor-specific API microversions?

Chris Friesen chris.friesen at windriver.com
Fri Mar 27 19:03:30 UTC 2015

On 03/27/2015 12:44 PM, Dan Smith wrote:
>> To quote John from an earlier email in this thread:
>> Its worth noting, we do have the "experimental" flag:
>> "
>> The first header specifies the version number of the API which was
>> executed. Experimental is only returned if the operator has made a
>> modification to the API behaviour that is non standard. This is only
>> intended to be a transitional mechanism while some functionality used
>> by cloud operators is upstreamed and it will be removed within a small
>> number of releases.
>> "
>> So if you have an extension that gets accepted upstream you can use the
>> experimental flag until you migrate to the upstream version of the
>> extension.
> Yes, but please note the last sentence in the quoted bit. This is to
> help people clean their dirty laundry. Going forward, you shouldn't
> expect to deliver features to your customers via this path.
>> That is *not* what I would call interoperability, this is exactly what
>> we do not want.
> +1.

So for the case where a customer really wants some functionality, and wants it 
*soon* rather than waiting for it to get merged upstream, what is the 
recommended implementation path for a vendor?

And what about stuff that's never going to get merged upstream because it's too 
specialized or too messy or depends on proprietary stuff?

I ask this as an employee of a vendor that provides some modifications that 
customers seem to find useful (using the existing extensions mechanism to 
control them) and we want to do the right thing here.  Some of the modifications 
could make sense upstream and we are currently working on pushing those, but 
it's not at all clear how we're supposed to handle the above scenarios once the 
existing extension code gets removed.


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