You can define processors in your configuration to process events before they are sent to the configured output. The libbeat library provides processors for reducing the number of exported fields, and processors for enhancing events with additional metadata. Each processor receives an event, applies a defined action to the event, and returns the event. If you define a list of processors, they are executed in the order they are defined in the configuration file.

event -> processor 1 -> event1 -> processor 2 -> event2 ...

The processors are defined in the Packetbeat configuration file.

For example, the following configuration includes a subset of the Packetbeat DNS fields so that only the requests and their response codes are reported:

filters:
  - include_fields:
      fields:
        - bytes_in
        - bytes_out
        - ip
        - client_ip
        - dns.question.name
        - dns.question.etld_plus_one
        - dns.response_code

The filtered event would look something like this:

{
  "@timestamp": "2016-03-28T14:48:21.732Z",
  "bytes_in": 32,
  "bytes_out": 48,
  "client_ip": "192.168.10.111",
  "dns": {
    "question": {
      "etld_plus_one": "google.com.",
      "name": "www.google.com."
    },
    "response_code": "NOERROR"
  },
  "ip": "8.8.8.8",
  "type": "dns"
}

If you would like to drop all the successful transactions, you can use the following configuration:

processors:
 - drop_event:
     when:
        equals:
           http.response.code: 200

If you don’t want to export raw data for the successful transactions:

processors:
 - drop_fields:
     when:
        equals:
           http.response.code: 200
     fields: ["request", "response"]

See Processors Configuration for more information.