Convert OS_* environment variable usage to use clouds.yaml

[Lance Bragstad]

During the Xena PTG we discussed the necessary steps to start testing the secure RBAC initiative. One of those items is to allow devstack to deploy secure RBAC by default.

Something that will help with this transition is to remove the current usage of OS_* environment variables during CLI invocations. OS_* environment variables pollute the runtime environment and bleed over between commands, which may need to run in different contexts (e.g., execute this command as a project-member, execute this command as a system-admin).

We already have a construct that manages these contexts in clouds.yaml. This bug report is to track the work for remove OS_* environment variable usage and instead rely on the profiles in clouds.yaml.

[Dr. Jens Harbott (j-harbott)]

Do you intend to just switch or will it be necessary to test both variants at least for some transition period? Also I'd like to have devstack match the process documented in the installation guide as far as possible, do you plan to update that, too? Last time I looked at that (years ago), this was blocked by glance using their own client and thus not supporting clouds.yaml.

[Dr. Jens Harbott (j-harbott)]

IIUC this change has been implemented.