Open Stack

Hi all, 

I've been pushing for a while now to convert devstack to completely use
the identity v3 API as we try to deprecate the v2.0 API. Currently all
the functions in functions-common consume the v3 API via setting --os
-identity-api-version 3 for each command to override the v2 default. 
https://review.openstack.org/#/c/186684/ changes this by exporting
OS_IDENTITY_API_VERSION=3 at the beginning meaning that all keystone
commands will now default to the v3 api. 

As we can see from the tests passing this works for the standard gate
job. However as this involves a command and argument change introducing
this has the potential to break anyone doing a custom CI or possibly
the devstack plugins if they do keystone operations directly. 

I'm interested to know from the community how we advertise this change
and what is going to be required to merge it?

Thanks, 

Jamie