filters.md

Filters as processors

You can use any filter as a processor in Fluent Bit.

{% hint style="info" %}

Only YAML configuration files support processors.

{% endhint %}

Examples

The following examples show how to configure filters as processors.

Grep

In this example, the Grep filter is used as an input processor to filter log events based on a regular expression pattern:

{% tabs %} {% tab title="fluent-bit.yaml" %}

parsers:
    - name: json
      format: json

pipeline:
    inputs:
        - name: tail
          path: /var/log/example.log
          parser: json

          processors:
              logs:
                  - name: grep
                    regex: log aa
    outputs:
        - name: stdout
          match: '*'

{% endtab %} {% endtabs %}

Lua

In this example configuration, an input plugin uses the Lua filter as a processor to add a new key hostname with the value monox. Then, an output plugin adds a new key named output with the value new data.

{% tabs %} {% tab title="fluent-bit.yaml" %}

  service:
    log_level: info
    http_server: on
    http_listen: 0.0.0.0
    http_port: 2021
  pipeline:
    inputs:
      - name: random
        tag: test-tag
        interval_sec: 1
        processors:
          logs:
            - name: modify
              add: hostname monox
            - name: lua
              call: append_tag
              code: |
                  function append_tag(tag, timestamp, record)
                     new_record = record
                     new_record["tag"] = tag
                     return 1, timestamp, new_record
                  end
    outputs:
      - name: stdout
        match: '*'
        processors:
          logs:
            - name: lua
              call: add_field
              code: |
                  function add_field(tag, timestamp, record)
                     new_record = record
                     new_record["output"] = "new data"
                     return 1, timestamp, new_record
                  end

{% endtab %} {% endtabs %}