keystone/api-ref/source/v3/samples/admin/auth-password-system-scoped-request-with-domain.json

{
    "auth": {
        "identity": {
            "methods": [
                "password"
            ],
            "password": {
                "user": {
                    "name": "admin",
                    "domain": {
                        "name": "Default"
                    },
                    "password": "devstacker"
                }
            }
        },
        "scope": {
            "system": {
                "all": true
            }
        }
    }
}