ClickHouse/tests/integration/test_distributed_ddl/configs/users.d/restricted_user.xml

<clickhouse>
    <users>
    	<restricted_user>
    		<password></password>
	        <profile>default</profile>
	        <quota>default</quota>
            <networks>
                    <ip>::/0</ip>
            </networks>

	        <allow_databases>
	           <database>db1</database>
	        </allow_databases>
    	</restricted_user>
    </users>
</clickhouse>