Blazar authenticates Nova requests with trust-scoped tokens. Sometime
during the Ocata cycle these requests started failing (possibly due to
stricter validation in Keystone) with the error:
BadRequest: Invalid input for field 'identity/password/user/password': None is not of type 'string' (HTTP 400)
This commit changes how the Nova client is configured to use the
token_endpoint authentication plugin combined with endpoint_override,
which allows to communicate with the Nova endpoint without extra
requests to Keystone. This is necessary between trust-scoped tokens
cannot re-authenticate with Keystone, which happens with other
authentication plugins.
Change-Id: Ibb6782140f41aea5e539e11f2618b3af2628fc4c
Closes-Bug: #1660564
81b85a11af