Splunk

Observability

Synopsis

Creates a Splunk HTTP Event Collector (HEC) target that sends events to one or more Splunk instances. Supports batching, compression, field normalization, and automatic load balancing across multiple endpoints.

Schema

- name: <string>
  description: <string>
  type: splunk
  pipelines: <pipeline[]>
  status: <boolean>
  properties:
    endpoints:
      - endpoint: <string>
        auth_type: <string>
        token: <string>
        secret: <string>
    index: <string>
    source_type: <string>
    source: <string>
    batch_size: <numeric>
    timeout: <numeric>
    tcp_routing: <boolean>
    use_compression: <boolean>
    insecure_skip_verify: <boolean>
    ca_name: <string>
    server_name: <string>
    cert_name: <string>
    key_name: <string>
    passphrase: <string>
    min_tls_version: <string>
    max_tls_version: <string>
    field_format: <string>
    debug:
      status: <boolean>
      dont_send_logs: <boolean>

Configuration

The following are the fields used to define the target:

Field	Required	Default	Description
`name`	Y		Target name
`description`	N	-	Optional description
`type`	Y		Must be `splunk`
`pipelines`	N	-	Optional post-processor pipelines
`status`	N	`true`	Enable/disable the target

Endpoint

Field	Required	Default	Description
`endpoint`	Y	-	Splunk HEC endpoint URL
`auth_type`	N	`token`	Authentication type: `token` or `secret`
`token`	Y*	-	HEC token when using token auth
`secret`	Y*	-	Bearer token when using secret auth

* = token is required when auth_type is token; secret is required when auth_type is secret.

Event

Field	Required	Default	Description
`index`	N	-	Default Splunk index
`source_type`	N	-	Default sourcetype for events
`source`	N	-	Default source for events
`batch_size`	N	10000	Number of events to batch before sending
`timeout`	N	30	Connection timeout in seconds

Connection

Field	Required	Default	Description
`tcp_routing`	N	`false`	Enable TCP routing header
`use_compression`	N	`true`	Enable gzip compression
`field_format`	N	-	Data normalization format. See applicable Normalization section

TLS

TLS is engaged by the endpoint URL scheme: an https:// endpoint enables it, an http:// endpoint does not. There is no status field, and these fields are top-level — they are not nested under a tls: block.

Field	Required	Default	Description
`insecure_skip_verify`	N	`false`	Skip server certificate verification. Use only for testing.
`ca_name`	N	-	CA bundle used to verify the server certificate. When unset, the host trust store is used.
`server_name`	N	-	SNI hostname override for the TLS handshake
`cert_name`	N*	-	Client certificate for mutual TLS
`key_name`	N*	-	Client private key for mutual TLS
`passphrase`	N	-	Passphrase for an encrypted private key
`min_tls_version`	N	`tls1.2`	Minimum accepted TLS version (`tls1.0`, `tls1.1`, `tls1.2`, `tls1.3`)
`max_tls_version`	N	`tls1.3`	Maximum accepted TLS version (`tls1.0`, `tls1.1`, `tls1.2`, `tls1.3`)

* = Mutual TLS requires both cert_name and key_name. Setting only one is a configuration error.

note

TLS material fields (cert_name, key_name, ca_name, client_ca_name) accept any of the following:

File name — resolved relative to the service root directory. Nested paths such as certs/prod/server.pem are supported.
Absolute path — honored only if it resolves inside the service root. Any path that escapes the root is refused.
Inline PEM content — used verbatim when the value contains -----BEGIN.
Environment variable — ${ENV_VAR}.
Vault reference — $secret{id=...} or $secret{store=...,ref=...}.

Scheduling

See Scheduling and Pool Behavior for interval and cron fields shared by all targets.

Debug Options

Field	Required	Default	Description
`debug.status`	N	`false`	Enable debug logging
`debug.dont_send_logs`	N	`false`	Process logs but don't send to target (testing)

Details

The Splunk HEC target sends log data to Splunk using the HTTP Event Collector (HEC) protocol. It supports multiple authentication methods, batching, compression, and automatic load balancing between endpoints.

The crowdstrike target type shares this implementation and uses the identical YAML schema. See CrowdStrike Falcon Next-Gen SIEM.

warning

Ensure your HEC tokens have the appropriate permissions and indexes enabled in Splunk. Invalid tokens or insufficient permissions will result in ingestion failures.

Events are automatically batched and compressed by default for optimal performance. When multiple endpoints are configured, the target randomly selects an endpoint for each batch to distribute load evenly across all available Splunk instances.

warning

Setting insecure_skip_verify to true is not recommended for production environments.

HEC Modes: JSON and RAW

The target supports both JSON and RAW HEC ingestion modes. The mode is determined by the endpoint URL path, not by a separate configuration field.

An endpoint URL ending in /services/collector/event (or the default /services/collector) uses JSON mode, where each event is sent as a structured JSON object with metadata fields (index, sourcetype, source) embedded in the payload.

An endpoint URL ending in /services/collector/raw uses RAW mode, where events are sent as plain text with metadata passed as query parameters. RAW mode is useful for forwarding pre-formatted log lines that should not be wrapped in JSON structure. When the incoming pipeline data contains a _raw field, the target extracts its value and sends it as the raw event body.

Named Streams

Endpoint URLs can include a query parameter to define a named stream. For example, https://hec.example.com:8088/services/collector/raw?paloalto creates a stream named paloalto using RAW mode, while https://hec.example.com:8088/services/collector/event?winevent creates a stream named winevent using JSON mode.

Named streams allow routing different event types through separate HEC paths within a single target configuration. A pipeline selects the stream for an event by setting index or table.

Events carrying neither are delivered to the endpoint configured without a query parameter, which acts as the catch-all stream. An event naming a stream that no endpoint defines also falls back to the catch-all; if no catch-all exists, the event is rejected.

All endpoints sharing a stream name must use the same mode. Mixing a /raw endpoint and an /event endpoint under one stream is a configuration error and the target fails to initialize.

Load Balancing and Failover

When multiple endpoints are configured, the target uses randomized load balancing. For each batch:

Endpoints are randomly shuffled
The batch is sent to the first endpoint
If it fails, the next endpoint in the shuffled list is tried
This continues until successful delivery or all endpoints fail

If only some endpoints fail but delivery eventually succeeds, the batch is cleared and a partial error is logged. If all endpoints fail, the batch is retained for retry and a complete failure error is returned.

Dynamic Routing

Pipeline processors can override the sourcetype and select the delivery stream on a per-event basis:

Setting schema or source in a pipeline overrides the sourcetype for that event. When both are set, schema wins.
Setting index or table in a pipeline selects the named stream the event is delivered to, as described above. It does not change the index value embedded in the JSON payload.

The index and source values sent to Splunk are always taken from the target's own properties and cannot be overridden per event.

Example pipeline configuration:

pipelines:
  - name: route_by_severity
    processors:
      - set:
          field: schema
          value: "app:error"
          if: "severity == 'error'"
      - set:
          field: index
          value: "critical"
          if: "severity == 'critical'"

Events matching the second condition are delivered to the stream named critical, which requires an endpoint configured with ?critical. Events that match no stream fall back to the endpoint configured without a query parameter.

Compression

Compression is enabled by default and uses gzip to reduce network bandwidth. This adds minimal CPU overhead but can significantly improve throughput for high-volume scenarios. Disable compression only if you have bandwidth to spare and want to reduce CPU usage.

Field Normalization

Field normalization helps standardize log data before sending it to Splunk, ensuring consistent data formats that can be easily correlated:

cim - Common Information Model

Normalization is applied before batching and sending to Splunk.

Examples

Basic

Send events to a single HEC endpoint...

targets:
  - name: basic_splunk
    type: splunk
    properties:
      endpoints:
        - endpoint: "https://splunk.example.com:8088/services/collector"
          auth_type: token
          token: "YOUR-HEC-TOKEN"
      index: "main"
      source_type: "vmetric"

Load Balanced

Configure load balancing and failover across multiple endpoints...

targets:
  - name: ha_splunk
    type: splunk
    properties:
      endpoints:
        - endpoint: "https://splunk1.example.com:8088/services/collector"
          auth_type: token
          token: "PRIMARY-TOKEN"
        - endpoint: "https://splunk2.example.com:8088/services/collector"
          auth_type: token
          token: "BACKUP-TOKEN"
        - endpoint: "https://splunk3.example.com:8088/services/collector"
          auth_type: token
          token: "TERTIARY-TOKEN"
      index: "main"
      source_type: "vmetric"
      batch_size: 5000

High-Volume

Configure for high throughput with larger batches and extended timeout...

targets:
  - name: perf_splunk
    type: splunk
    properties:
      endpoints:
        - endpoint: "https://splunk.example.com:8088/services/collector"
          auth_type: token
          token: "YOUR-HEC-TOKEN"
      index: "metrics"
      source_type: "vmetric"
      batch_size: 20000
      timeout: 60
      use_compression: true
      tcp_routing: true

With Field Normalization

Using CIM field normalization for better Splunk integration...

targets:
  - name: normalized_splunk
    type: splunk
    properties:
      endpoints:
        - endpoint: "https://splunk.example.com:8088/services/collector"
          auth_type: token
          token: "YOUR-HEC-TOKEN"
      index: "main"
      source_type: "normalized_logs"
      field_format: "cim"

Secure

Using secret-based auth with TLS verification and custom source...

targets:
  - name: secure_splunk
    type: splunk
    properties:
      endpoints:
        - endpoint: "https://splunk.example.com:8088/services/collector"
          auth_type: secret
          secret: "YOUR-BEARER-TOKEN"
      index: "secure"
      source_type: "vmetric"
      source: "production_cluster"
      insecure_skip_verify: false
      use_compression: true

RAW Mode

Send raw log lines using HEC RAW mode with a named stream...

targets:
  - name: raw_splunk
    type: splunk
    properties:
      endpoints:
        - endpoint: "https://splunk.example.com:8088/services/collector/raw?firewall"
          auth_type: token
          token: "YOUR-HEC-TOKEN"
      index: "network"
      source_type: "paloalto:traffic"
      source: "pan-fw-01"

No Compression

Disable compression to reduce CPU overhead when bandwidth is not a concern...

targets:
  - name: uncompressed_splunk
    type: splunk
    properties:
      endpoints:
        - endpoint: "https://splunk.example.com:8088/services/collector"
          auth_type: token
          token: "YOUR-HEC-TOKEN"
      index: "main"
      source_type: "vmetric"
      use_compression: false

Synopsis​

Schema​

Configuration​

Endpoint​

Event​

Connection​

TLS​

Scheduling​

Debug Options​

Details​

HEC Modes: JSON and RAW​

Named Streams​

Load Balancing and Failover​

Dynamic Routing​

Compression​

Field Normalization​

Examples​

Basic​

Load Balanced​

High-Volume​

With Field Normalization​

Secure​

RAW Mode​

No Compression​