Open Stack

Starting a new thread to continue a thought that came up in
http://lists.openstack.org/pipermail/openstack-dev/2016-February/086457.html.
The Nova API microversion framework allows for backwards compatible and
backwards incompatible changes but there is no way to programmatically
distinguish the two. This means that as a user of the API I need to
understand every change between the version I'm using now and a new
version I would like to move to in case an intermediate version changes
default behaviors or removes something I'm currently using.

I would suggest that a more user friendly approach would be to
distinguish the two types of changes. Perhaps something like 2.x.y where
x is bumped for a backwards incompatible change and y is still
monotonically increasing regardless of bumps to x. So if the current
version is 2.2.7 a new backwards compatible change would bump to 2.2.8
or a new backwards incompatible change would bump to 2.3.8. As a user
this would allow me to fairly freely bump the version I'm consuming
until x changes at which point I need to take more care in moving to a
new version.

Just wanted to throw the idea out to get some feedback. Or perhaps this
was already discussed and dismissed when microversions were added and I
just missed it.