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Greetings,

The v3 API effort has been going for a few release cycles now.  As we
approach the Icehouse release, we are faced with the following question:
"Is it time to mark v3 stable?"

My opinion is that I think we need to leave v3 marked as experimental
for Icehouse.

There are a number of reasons for this:

1) Discussions about the v2 and v3 APIs at the in-person Nova meetup
last week made me come to the realization that v2 won't be going away
*any* time soon.  In some cases, users have long term API support
expectations (perhaps based on experience with EC2).  In the best case,
we have to get all of the SDKs updated to the new API, and then get to
the point where everyone is using a new enough version of all of these
SDKs to use the new API.  I don't think that's going to be quick.

We really don't want to be in a situation where we're having to force
any sort of migration to a new API.  The new API should be compelling
enough that everyone *wants* to migrate to it.  If that's not the case,
we haven't done our job.

2) There's actually quite a bit still left on the existing v3 todo list.
 We have some notes here:

https://etherpad.openstack.org/p/NovaV3APIDoneCriteria

One thing is nova-network support.  Since nova-network is still not
deprecated, we certainly can't deprecate the v2 API without nova-network
support in v3.  We removed it from v3 assuming nova-network would be
deprecated in time.

Another issue is that we discussed the tasks API as the big new API
feature we would include in v3.  Unfortunately, it's not going to be
complete for Icehouse.  It's possible we may have some initial parts
merged, but it's much smaller scope than what we originally envisioned.
 Without this, I honestly worry that there's not quite enough compelling
functionality yet to encourage a lot of people to migrate.

3) v3 has taken a lot more time and a lot more effort than anyone
thought.  This makes it even more important that we're not going to need
a v4 any time soon.  Due to various things still not quite wrapped up,
I'm just not confident enough that what we have is something we all feel
is Nova's API of the future.


Let's all take some time to reflect on what has happened with v3 so far
and what it means for how we should move forward.  We can regroup for Juno.

Finally, I would like to thank everyone who has helped with the effort
so far.  Many hours have been put in to code and reviews for this.  I
would like to specifically thank Christopher Yeoh for his work here.
Chris has done an *enormous* amount of work on this and deserves credit
for it.  He has taken on a task much bigger than anyone anticipated.
Thanks, Chris!

-- 
Russell Bryant