Send logs to Splunk HTTP Event Collector

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

To get more details about how to setup the HEC in Splunk please refer to the following documentation: Splunk / Use the HTTP Event Collector

Configuration Parameters





IP address or hostname of the target Splunk service.


TCP port of the target Splunk service.



Specify the Authentication Token for the HTTP Event Collector interface.


When enabled, the record keys and values are set in the top level of the map instead of under the event key.

note: refer to the Sending Raw Events section below for more details to make this option work properly.



Optional username for Basic Authentication on HEC


Password for user defined in HTTP_User


Splunk output plugin supports TTL/SSL, for more details about the properties available and general configuration, please refer to the TLS/SSL section.

Getting Started

In order 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 in two ways, through the -p argument (property), e.g:

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

Configuration File

In your main configuration file append the following Input & Output sections:

Name cpu
Tag cpu
Name splunk
Match *
Port 8088
TLS.Verify Off
Message_Key my_key

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.

If you would like 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. Note: 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:

Name cpu
Tag cpu
# nest the record under the 'event' key
Name nest
Match *
Operation nest
Wildcard *
Nest_under event
# add event metadata
Name modify
Match *
Add index my-splunk-index
Add host my-host
Name splunk
Match *
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": {

For more information on the Splunk HEC payload format and all event meatadata Splunk accepts, see here: http://docs.splunk.com/Documentation/Splunk/latest/Data/AboutHEC

Sending Raw Events

If the option splunk_send_raw has been enabled, the user must take care to put 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 will return a HTTP error 400.

Consider the following example:

splunk_send_raw off

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

splunk_send_raw on

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

For up to date information about the valid keys in the top level object, refer to the Splunk documentation:


Splunk Metric Index

With Splunk version 8.0> you can also use the Fluent Bit Splunk output plugin to send data to metric indices. This allows you to perform visualizations, metric queries, and analysis with other metrics you may be collecting. This is based off of Splunk 8.0 support of multi metric support via single JSON payload, more details can be found on Splunk's documentation page

Sending to a Splunk Metric index requires the use of Splunk_send_raw option being enabled and formatting the message properly. This includes three 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.

name cpu
tag cpu
# 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
Set source fluent-bit
Set sourcetype custom
# ensure splunk_send_raw is on
name splunk
match *
host <HOST>
port 8088
splunk_send_raw on
splunk_token f9bd5bdb-c0b2-4a83-bcff-9625e5e908db
tls on
tls.verify off