Migrate the stored user_creds, which currently only supports
storing username/password credentials to use the keystone v3
API OS-TRUST extension, which allows explicit impersonation of
users calling heat (trustors) by the heat service user (the
trustee)
Note this feature is made optional via a new config option,
defaulted to off, and it requires the following patches to
keystoneclient (in 0.3.2 release) and keystone to work:
https://review.openstack.org/#/c/39899/https://review.openstack.org/#/c/42456/
Also note that if the feature is enabled, by setting
deferred_auth_method=trusts in heat.conf, you must add
a keystone_authtoken section, which is also used by the
keystoneclient auth_token middleware.
blueprint heat-trusts
Change-Id: I288114d827481bc0a24eba4556400d98b1a44c09
e686699b00