[openstack-dev] [cinder] adding a new /v3 endpoint for api-microversions

Duncan Thomas duncan.thomas at gmail.com
Sun Feb 21 17:59:17 UTC 2016

On 21 February 2016 at 19:34, Jay S. Bryant <jsbryant at electronicjungle.net>

> Spent some time talking to Sean about this on Friday afternoon and bounced
> back and forth between the two options.  At first, /v3 made the most sense
> to me ... at least it did at the meetup.  With people like Sean Dague and
> Morgan Fainberg weighing in with concerns, it seems like we should
> reconsider.  Duncan, your comment here about customers moving when they are
> ready is somewhat correct.  That, however, I am concerned is a a small
> subset of the users.  I think many users want to move but don't know any
> better.  That was what we encountered with our consumers.  They didn't
> understand that they needed to update the endpoint and couldn't figure out
> why their new functions weren't working.
> So, I am leaning towards going with the /v2 endpoint and making sure that
> the clients we can control are set up properly and we put safety checks in
> the server end.  I think that may be the safest way to go.

So we can't get users to change endpoints, or write our libraries to have
sensible defaults, but we're somehow going to magically get consumers to do
the much harder job of doing version probes in their code/libraries so that
they don't get surprised by unexpected results? This seems to be entirely
nuts. If 'they' can't change endpoints (and we can't make the libraries we
write just do the right thing without needing to change endpoints) then how
are 'they' expected to do the probing magic that will be required at some
unpredictable poin tin the future, but which you'll get away without until

This would also make us inconsistent with the other projects that have
implemented microversions - so we're changing a known working pattern, to
try to avoid the problem of a user having to get their settings right if
they want new functionality, and hoping this doesn't introduce entirely
predictable and foreseeable bugs in the future that can't actually be fixed
except by checking/changing every client library out there? There's no way
that's a sensible API design.

Duncan Thomas
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