ClickHouse/tests/integration/test_cluster_copier/configs/conf.d/clusters_trivial.xml

<?xml version="1.0"?>
<clickhouse>
    <remote_servers>
        <source_trivial_cluster>
            <shard>
                <replica>
                    <host>first_trivial</host>
                    <port>9000</port>
                </replica>
            </shard>
        </source_trivial_cluster>
        <destination_trivial_cluster>
            <shard>
                <replica>
                    <host>second_trivial</host>
                    <port>9000</port>
                </replica>
            </shard>
        </destination_trivial_cluster>
    </remote_servers>
</clickhouse>