More than one user exists with the name

[amurleopard]

When adding roles to a project with a clashing user, you are likely to see this error.

$ openstack role add --project offworld --user admin admin
More than one user exists with the name 'admin'.

You have to use the additional option to the "openstack role add" command, adding the --user-domain to the specific domain will resolve this.

$ openstack role add --user-domain mars --project offworld --user admin admin