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Splunk

Send logs to Splunk HTTP Event Collector

The Splunk output plugin lets you ingest your records into a Splunk Enterprise service through the HTTP Event Collector (HEC) interface.

To learn how to set up the HEC in Splunk, refer to Splunk / Use the HTTP Event Collector.

Configuration parameters

Connectivity, transport, and authentication configuration properties:

Key
Description
Default

host

IP address or hostname of the target Splunk service.

127.0.0.1

port

TCP port of the target Splunk service.

8088

splunk_token

Specify the authentication token for the HTTP Event Collector interface.

none

http_user

Optional username for basic authentication on HEC.

none

http_passwd

Password for user defined in http_user.

none

http_buffer_size

Buffer size used to receive Splunk HTTP responses.

2M

compress

Set payload compression mechanism. Allowed value: gzip.

none

channel

Specify X-Splunk-Request-Channel header for the HTTP Event Collector interface.

none

http_debug_bad_request

If the HTTP server response code is 400 (bad request) and this flag is enabled, it will print the full HTTP request and response to the stdout interface. This feature is available for debugging purposes.

none

workers

The number of workers to perform flush operations for this output.

2

Content and Splunk metadata (fields) handling configuration properties:

Key
Description
Default

splunk_send_raw

When enabled, the record keys and values are set in the top level of the map instead of under the event key. See Sending Raw Events to configure this option.

off

event_key

Specify the key name that will be used to send a single value as part of the record.

none

event_host

Specify the key name that contains the host value. This option allows a record accessors pattern.

none

event_source

Set the source value to assign to the event data.

none

event_sourcetype

Set the sourcetype value to assign to the event data.

none

event_sourcetype_key

Set a record key that will populate sourcetype. If the key is found, it will have precedence over the value set in event_sourcetype.

none

event_index

The name of the index by which the event data is to be indexed.

none

event_index_key

Set a record key that will populate the index field. If the key is found, it will have precedence over the value set in event_index.

none

event_field

Set event fields for the record. This option can be set multiple times and the format is key_name record_accessor_pattern.

none

TLS / SSL

The Splunk output plugin supports TLS/SSL. For more details about the properties available and general configuration, see TLS/SSL.

Get started

To insert records into a Splunk service, you can run the plugin from the command line or through the configuration file.

Command line

The Splunk plugin can read the parameters from the command line through the -p argument (property):

fluent-bit -i cpu -t cpu -o splunk -p host=127.0.0.1 -p port=8088 \
  -p tls=on -p tls.verify=off -m '*'

Configuration file

In your main configuration file append the following sections:

pipeline:
  inputs:
    - name: cpu
      tag: cpu

  outputs:
    - name: splunk
      match: '*'
      host: 127.0.0.1
      port: 8088
      tls: on
      tls.verify: off

Data format

By default, the Splunk output plugin nests the record under the event key in the payload sent to the HEC. It will also append the time of the record to a top level time key.

To customize any of the Splunk event metadata, such as the host or target index, you can set Splunk_Send_Raw On in the plugin configuration, and add the metadata as keys/values in the record. With Splunk_Send_Raw enabled, you are responsible for creating and populating the event section of the payload.

For example, to add a custom index and hostname:

pipeline:
  inputs:
    - name: cpu
      tag: cpu

  filters:
    # nest the record under the 'event' key
    - name: nest
      match: '*'
      operation: nest
      wildcard: '*'
      nest_under: event

    - name: modify
      match: '*'
      add:
        - index my-splunk-index
        - host my-host

  outputs:
    - name: splunk
      match: '*'
      host: 127.0.0.1
      splunk_token: 'xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxx'
      splunk_send_raw: On

This will create a payload that looks like:

{
  "time": "1535995058.003385189",
  "index": "my-splunk-index",
  "host": "my-host",
  "event": {
    "cpu_p":0.000000,
    "user_p":0.000000,
    "system_p":0.000000
  }
}

Sending raw events

If the option splunk_send_raw has been enabled, the user must add all log details in the event field, and only specify fields known to Splunk in the top level event. If there is a mismatch, Splunk returns an HTTP 400 Bad Request status code.

Consider the following examples:

  • splunk_send_raw off

    {"time": "SOMETIME", "event": {"k1": "foo", "k2": "bar", "index": "applogs"}}

  • splunk_send_raw on

    {"time": "SOMETIME", "k1": "foo", "k2": "bar", "index": "applogs"}

For up-to-date information about the valid keys, see Getting Data In.

Splunk metric index

With Splunk version 8.0 and later, you can use the Fluent Bit Splunk output plugin to send data to metric indices. This lets you perform visualizations, metric queries, and analysis with other metrics you might be collecting. This is based off of Splunk 8.0 support of multi metric support using single JSON payload, more details can be found in Splunk metrics documentation

Sending to a Splunk metric index requires the use of Splunk_send_raw option being enabled and formatting the message properly. This includes these specific operations:

  • Nest metric events under a fields property

  • Add metric_name: to all metrics

  • Add index, source, sourcetype as fields in the message

Example configuration

The following configuration gathers CPU metrics, nests the appropriate field, adds the required identifiers and then sends to Splunk.

pipeline:
  inputs:
    - name: cpu
      tag: cpu

  filters:
    # Move CPU metrics to be nested under "fields" and
    # add the prefix "metric_name:" to all metrics
    # NOTE: you can change Wildcard field to only select metric fields
    - name: nest
      match: cpu
      wildcard: '*'
      operation: nest
      nest_under: fields
      add_prefix: 'metric_name:'

    # Add index, source, sourcetype
    - name: modify
      match: cpu
      set:
        - index cpu-metrics
        - source fluent-bit
        - sourcetype custom

  outputs:
    - name: splunk
      match: '*'
      host: <HOST>
      port: 8088
      splunk_token: 'xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxx'
      tls: on
      tls.verify: off

Send metrics events of Fluent Bit

In Fluent Bit 2.0 or later, you can send Fluent Bit metrics the events type into Splunk using Splunk HEC. This lets you perform visualizations, metric queries, and analysis with directly sent using Fluent Bit metrics. This is based off Splunk 8.0 support of multi metric support using a single concatenated JSON payload.

Sending Fluent Bit metrics into Splunk requires the use of collecting Fluent Bit metrics plugins, whether events type of logs or metrics can be distinguished automatically. You don't need to pay attentions about the type of events.

This example includes two specific operations

  • Collect node or Fluent Bit internal metrics

  • Send metrics as single concatenated JSON payload

pipeline:
  inputs:
    - name: node_exporter_metrics
      tag: node_exporter_metrics

  outputs:
    - name: splunk
      match: '*'
      host: <HOST>
      port: 8088
      splunk_token: 'xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxx'
      tls: on
      tls.verify: off

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