ClickHouse/dbms/tests/integration/test_dictionaries_mysql/configs/remote_servers.xml

<yandex>
    <remote_servers>
        <test_cluster>
            <shard>
                <replica>
                    <host>instance</host>
                    <port>9000</port>
                </replica>
            </shard>
        </test_cluster>
    </remote_servers>
</yandex>