ClickHouse/tests/config/config.d/clusters.xml

<yandex>
    <remote_servers>
        <test_cluster_two_shards_different_databases>
             <shard>
                 <replica>
                     <default_database>shard_0</default_database>
                     <host>localhost</host>
                     <port>9000</port>
                 </replica>
             </shard>
             <shard>
                 <replica>
                     <default_database>shard_1</default_database>
                     <host>localhost</host>
                     <port>9000</port>
                 </replica>
             </shard>
        </test_cluster_two_shards_different_databases>
        <test_cluster_one_shard_two_replicas>
             <shard>
                 <replica>
                     <host>127.0.0.1</host>
                     <port>9000</port>
                 </replica>
                 <replica>
                     <host>127.0.0.2</host>
                     <port>9000</port>
                 </replica>
             </shard>
        </test_cluster_one_shard_two_replicas>
    </remote_servers>
</yandex>