[Openstack-operators] [nova] Should we allow passing new user_data during rebuild?

Clint Byrum clint at fewbar.com
Tue Oct 3 17:12:51 UTC 2017

Excerpts from Matt Riedemann's message of 2017-10-03 10:53:44 -0500:
> We plan on deprecating personality files from the compute API in a new 
> microversion. The spec for that is here:
> https://review.openstack.org/#/c/509013/
> Today you can pass new personality files to inject during rebuild, and 
> at the PTG we said we'd allow passing new user_data to rebuild as a 
> replacement for the personality files.
> However, if the only reason one would need to pass personality files 
> during rebuild is because we don't persist them during the initial 
> server create, do we really need to also allow passing user_data for 
> rebuild? The initial user_data is stored with the instance during 
> create, and re-used during rebuild, so do we need to allow updating it 
> during rebuild?

My personal opinion is that rebuild is an anti-pattern for cloud, and
should be frozen and deprecated. It does nothing but complicate Nova
and present challenges for scaling.

That said, if it must stay as a feature, I don't think updating the
user_data should be a priority. At that point, you've basically created an
entirely new server, and you can already do that by creating an entirely
new server.

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