ClickHouse/tests/config/config.d/s3_storage_policy_by_default.xml

<clickhouse>
    <storage_configuration>
        <disks>
            <s3>
                <type>s3</type>
                <endpoint>http://localhost:11111/test/test/</endpoint>
                <access_key_id>clickhouse</access_key_id>
                <secret_access_key>clickhouse</secret_access_key>
            </s3>
            <cached_s3>
                <type>cache</type>
                <max_size>1Gi</max_size>
                <path>cached_s3/</path>
                <disk>s3</disk>
            </cached_s3>
        </disks>
        <policies>
            <s3>
                <volumes>
                    <main><disk>cached_s3</disk></main>
                </volumes>
            </s3>
        </policies>
    </storage_configuration>
    <merge_tree>
        <storage_policy>s3</storage_policy>
    </merge_tree>
</clickhouse>