[openstack-dev] [nova] Microversions support for extensions without Controller

Alexandre Levine alexandrelevine at gmail.com
Sat Dec 12 18:34:00 UTC 2015

Hi all,

os-user-data extension implements server_create method to add user_data 
for server creation. No Controller is used for this, only "class 

I want to add server_update method allowing to update the user_data. 
Obviously I have to add it as a microversioned functionality.

And here is the problem: there is no information about the incoming 
request version in this code. It is available for Controllers only. But 
checking the version in controller would be too late, because the 
instance is already updated (non-generator extensions are post-processed).

Can anybody guide me how to resolve this collision?

Would it be possible to just retroactively add the user_data 
modification for the whole 2.1 version skipping the microversioning? Or 
we need to change nova so that request version is passed through to 

Best regards,
   Alex Levine

P.S. Sorry for the second attempt - previous letter went with 
[openstack] instead of [openstack-dev] in the Subject.

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