ClickHouse/tests/integration/test_distributed_load_balancing/configs/remote_servers.xml

<yandex>
    <remote_servers>
        <replicas_cluster>
            <shard>
                <replica>
                    <host>n1</host>
                    <port>9000</port>
                </replica>
                <replica>
                    <host>n2</host>
                    <port>9000</port>
                </replica>
                <replica>
                    <host>n3</host>
                    <port>9000</port>
                </replica>
            </shard>
        </replicas_cluster>

        <replicas_priority_cluster>
            <shard>
                <replica>
                    <host>n1</host>
                    <port>9000</port>
                    <priority>0</priority>
                </replica>
                <replica>
                    <host>n2</host>
                    <port>9000</port>
                    <!-- will not be quieried, if n1 and n3 has errors_count == 0 -->
                    <!-- <priority>1</priority> -->
                </replica>
                <replica>
                    <host>n3</host>
                    <port>9000</port>
                    <priority>0</priority>
                </replica>
            </shard>
        </replicas_priority_cluster>

        <replicas_priority_negative_cluster>
            <shard>
                <replica>
                    <host>n1</host>
                    <port>9000</port>
                    <priority>-1</priority>
                </replica>
                <replica>
                    <host>n2</host>
                    <port>9000</port>
                    <!-- will not be quieried, if n1 and n3 has errors_count == 0 -->
                    <priority>0</priority>
                </replica>
                <replica>
                    <host>n3</host>
                    <port>9000</port>
                    <priority>-1</priority>
                </replica>
            </shard>
        </replicas_priority_negative_cluster>

        <!-- For JOIN with system.clusters -->
        <shards_cluster>
            <node>
                <host>n1</host>
                <port>9000</port>
            </node>
            <node>
                <host>n2</host>
                <port>9000</port>
            </node>
            <node>
                <host>n3</host>
                <port>9000</port>
            </node>
        </shards_cluster>
    </remote_servers>
</yandex>