Fluentd does not flush its buffer to the file output

[hadrian08]

Hello,
Evaluating fluentd for aggregating distributed log files. Running on Windows Server 2019. We have the following config:

<source>
  @type forward
  port 9090
  bind 0.0.0.0
  tag myTag
  <security>
    self_hostname my-host
    shared_key shared-key
  </security>
</source>

<match myTag>
  @type file 
  path c:\logs\test.log
  append true
    <format>
      @type json
      output_tag false
    </format>
</match>

Running version: starting fluentd-1.14.6 ruby="2.7.6"
I see the internal buffer file generated (buffer.b5dfe74542d330f8d3adf50b2bfae0ae3.log) and it has 35kb worth of data; and yet nothing is being flushed to the test.log folder. No file created at the target file path. What prevents it?
Even after terminating the fluentd process the internal buffer still does not flush the data.
Thanks, -hadrian

[hadrian08]

Figured it out eventually; it requires the buffer section in order to write to the specified file and flush on shutdown; also needed it to be close to real time.

<source>
  @type forward
  port 9090
  bind 0.0.0.0
  tag myTag
  <security>
    self_hostname my-host
    shared_key shared-key
  </security>
</source>

<match myTag>
  @type file 
  path c:\logs\test.log
  append true
    <format>
      @type json
      output_tag false
    </format>
    <buffer>
       flush_mode interval
       flush_interval 5s
       flush_at_shutdown true
    </buffer>
</match>