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 ---- On Tue, 17 Sep 2019 06:46:31 -0700 Sean Mooney <smooney at redhat.com> wrote ----
 > On Tue, 2019-09-17 at 09:23 -0400, Eric Harney wrote:
 > > On 9/16/19 6:59 PM, Sean Mooney wrote:
 > > > On Mon, 2019-09-16 at 17:11 -0500, Sean McGinnis wrote:
 > > > > > 
 > > > > > Backend/type specific information leaking out of the API dynamically like
 > > > > > that is definitely an interoperability problem and as you said it sounds
 > > > > > like it's been that way for a long time. The compute servers diagnostics API
 > > > > > had a similar problem for a long time and the associated Tempest test for
 > > > > > that API was disabled for a long time because the response body was
 > > > > > hypervisor specific, so we eventually standardized it in a microversion so
 > > > > > it was driver agnostic.
 > > > > > 
 > > > > 
 > > > > Except this isn't backend specific information that is leaking. It's just
 > > > > reflecting the configuration of the system.
 > > > 
 > > > yes and config driven api behavior is also an iterop problem.
 > > > ideally you should not be able to tell if cinder is abcked by ceph or emc form the
 > > > api responce at all.
 > > > 
 > > > sure you might have a volume type call ceph and another called emc but both should be
 > > > report capasty in the same field with teh same unit.
 > > > 
 > > > ideally you would have a snapshots or gigabytes quota and option ly associate that with a volume types
 > > > but shanshot_ceph is not interoperable aross could if that exstis with that name solely becaue ceph was used on the
 > > > backend. as a client i would have to look at snapshost* to figure out my quotat and in princiapal that is an
 > > > ubounded
 > > > set.
 > > 
 > > I think you are confusing types vs backends here.  In my example, it was 
 > > called "snapshots_ceph" because there was a type called "ceph".  That's 
 > > an admin choice, not a behavior of the API.
 > or it could have been express in the api with a dedicated type filed and 
 > 
 > so you would always have a snapshots filed regardless of the volume type but have a since
 > type filed per quota set  that identifed what type it applied too.

IMO, the best way is to make it in an array structure and volume_type specific quotas can be optional items in mandatory 'snapshots' array field. 
For example:

{
    "quota_set": {
       .
       .
        "snapshots": {
            "total/project": 10,
            "ceph": -1,
            "lvm-thin": -1,
            "lvmdriver-1": -1,
        }
}

-gmann

 > 
 > 
 >