Comment 32 for bug 1446704

Agreement has been made that option "rgw_s3_auth_use_keystone"
will be controlled through Fuel since 10.0. For 9.0 and older releases
a technical bulletin explaining the associated trade-off and manual
procedure for enabling the S3/Keystone integration will be issued.

For 9.0 it's enough to add support to fuel-library to manage the parameter.