Splunk

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
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.
​
http_user
Optional username for Basic Authentication on HEC
​
http_passwd
Password for user defined in HTTP_User
​
http_buffer_size
Buffer size used to receive Splunk HTTP responses
2M
compress
Set payload compression mechanism. The only available option is gzip.
​
channel
Specify X-Splunk-Request-Channel Header for the HTTP Event Collector interface.
​
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.
​
Workers
Enables dedicated thread(s) for this output. Default value is set since version 1.8.13. For previous versions is 0.
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. Refer to the Sending Raw Events section from the docs for more details to make this option work properly.
off
event_key
Specify the key name that will be used to send a single value as part of the record.
​
event_host
Specify the key name that contains the host value. This option allows a record accessors pattern.
​
event_source
Set the source value to assign to the event data.
​
event_sourcetype
Set the sourcetype value to assign to the event data.
​
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.
​
event_index
The name of the index by which the event data is to be indexed.
​
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.
​
event_field
Set event fields for the record. This option can be set multiple times and the format is key_name record_accessor_pattern.
​
TLS / SSL
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=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 Input & Output sections:
[INPUT]
    Name  cpu
    Tag   cpu
​
[OUTPUT]
    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.
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:
[INPUT]
    Name  cpu
    Tag   cpu
​
# nest the record under the 'event' key
[FILTER]
    Name nest
    Match *
    Operation nest
    Wildcard *
    Nest_under event
​
# add event metadata
[FILTER]
    Name      modify
    Match     *
    Add index my-splunk-index
    Add host  my-host
​
[OUTPUT]
    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
    }
}
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:
​http://docs.splunk.com/Documentation/Splunk/latest/Data/AboutHEC​
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.
[INPUT]
    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    
[FILTER]
    Name nest
    Match cpu
    Wildcard *
    Operation nest
    Nest_under fields
    Add_Prefix metric_name:
​
# Add index, source, sourcetype
[FILTER]
    Name    modify
    Match   cpu
    Set index cpu-metrics 
    Set source fluent-bit
    Set sourcetype custom
​
# ensure splunk_send_raw is on
[OUTPUT]
    name splunk 
    match *
    host <HOST>
    port 8088
    splunk_send_raw on
    splunk_token f9bd5bdb-c0b2-4a83-bcff-9625e5e908db 
    tls on
    tls.verify off

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Configuration Parameters

TLS / SSL

Getting Started

Command Line

Configuration File

Data format

Sending Raw Events

Splunk Metric Index

Example Configuration