ClickHouse/tests/integration/test_cluster_discovery/config/config_keepers.xml

<clickhouse>
    <zookeeper>
        <node index="1">
            <host>zoo1</host>
            <port>2181</port>
        </node>
        <node index="2">
            <host>zoo2</host>
            <port>2181</port>
        </node>
        <node index="3">
            <host>zoo3</host>
            <port>2181</port>
        </node>
    </zookeeper>
    <auxiliary_zookeepers>
        <zookeeper2>
            <node index="1">
                <host>zoo1</host>
                <port>2181</port>
            </node>
        </zookeeper2>
    </auxiliary_zookeepers>
</clickhouse>