Open Stack

After coming across the no-flavors blueprint at
https://blueprints.launchpad.net/nova/+spec/no-flavors and exchanging a few
e-mails with the author, we thought it would be good to take Russell's
advice and take to the mailing list for feedback.

A more detailed specification is at
https://wiki.openstack.org/wiki/DynamicFlavors.

To summarize, this proposal is about allowing the create server and resize
server APIs to take the same flavor element as used in create flavor in
addition to a flavorRef element.  The use of the flavor element should be
controlled by policy and by default be restricted to admins to keep with
current behavior.  Deployments that wish to expose this to non-admins would
have to make an explicit policy change.

>From an implementation standpoint, extensions would be added to the APIs to
handle the flavor element.  When encountered, a MD5 hash is computed on the
flavor data structure and a matching hash looked for among existing
flavors. If no match is found, a new, non-public flavor is created. The
flavor element is then replaced with a flavorRef element and processing
continues as-is today.   This implementation should be non-invasive and
have minimal impact to existing code paths (other than to refactor create
flavor to re-use in all 3 places)

One open question is if we need more constraints on the values other than
overall usage being constrained by quota and the size of any single
resource by what the scheduler can deploy. One proposal is to add min, max,
and/or step values to be enforced by the extension.  However, one side
effect is that it adds complexity by requiring a new API to convey those
limits.

Would others find this useful?  If desired, we can post an initial
implementation.

Michael

-------------------------------------------------
Michael Fork
Architect, OpenStack Development
IBM Systems & Technology Group
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