Can't specify OS_INTERFACE with os-client-config library

[Drew Freiberger]

In an environment with multiple spaces for keystone/nova/neutron endpoints, you must bind your application to the oam-space (for nagios access), internal-space, and public-space. internalURL endpoint keystone URL is returned by keystone:identity-credentials, which requires the internal-space, but the default interface for os-client-config seems to be public only, as it's not picking up the OS_INTERNAL environment variable.

Suggest recoding to openstacksdk library and set up "use-internal-endpoints" similiar to other openstack charms to remove need for access to external/public network for the monitoring service.

[Xav Paice (xavpaice)]

This has since been addressed by adding extra bindings for checking against all endpoints in the Keystone catalog.