ClickHouse/tests/integration/test_s3_cluster/configs/cluster.xml

<clickhouse>
    <remote_servers>
    <cluster_simple>
        <shard>
            <replica>
                <host>s0_0_0</host>
                <port>9000</port>
            </replica>
            <replica>
                <host>s0_0_1</host>
                <port>9000</port>
            </replica>
        </shard>
        <shard>
            <replica>
                <host>s0_1_0</host>
                <port>9000</port>
            </replica>
        </shard>
    </cluster_simple>

    <!-- A part of the cluster above, represents only one shard-->
    <first_shard>
        <shard>
            <replica>
                <host>s0_0_0</host>
                <port>9000</port>
            </replica>
            <replica>
                <host>s0_0_1</host>
                <port>9000</port>
            </replica>
        </shard>
    </first_shard>

    <cluster_non_existent_port>
        <shard>
            <replica>
                <host>s0_0_0</host>
                <port>9000</port>
            </replica>
        </shard>
        <shard>
            <replica>
                <host>s0_0_0</host>
                <port>19000</port>
            </replica>
        </shard>
    </cluster_non_existent_port>

    </remote_servers>
    <macros>
        <default_cluster_macro>cluster_simple</default_cluster_macro>
    </macros>
</clickhouse>