Formatter Plugins

Fluentd has nine (9) types of plugins:

This article gives an overview of the Formatter Plugin.


Sometimes, the output format for an output plugin does not meet one's needs. Fluentd has a pluggable system called Formatter that lets the user extend and re-use custom output formats.

How To Use

For an output plugin that supports Formatter, the <format> directive can be used to change the output format.

For example, by default, out_file plugin outputs data as

2014-08-25 00:00:00 +0000<TAB><TAB>{"k1":"v1", "k2":"v2"}

However, if you set @type json in <format> like this:

  @type file
  path /path/to/file
    @type json

The output changes to

{"k1":"v1", "k2":"v2"}

i.e., each line is a single JSON object without "time" and "tag" fields. If you want to include "time" and "tag", use Inject section.

See this section to learn how to develop a custom formatter.

List of Built-in Formatters

List of Output/Filter Plugins with Formatter Support

If this article is incorrect or outdated, or omits critical information, please let us know. Fluentd is an open-source project under Cloud Native Computing Foundation (CNCF). All components are available under the Apache 2 License.

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