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Splunk Single Instance

The Splunk Enterprise Destination can stream data to a free Splunk Cloud instance. From the perspective of the receiving Splunk Cloud instance, the data arrives cooked and parsed.

For a Standard Splunk Cloud instance whose ../default/outputs.conf file contains multiple indexer entries, you must instead use Cribl Edge’s Splunk Load Balanced Destination.

Type: Streaming | TLS Support: Configurable | PQ Support: Yes

Configuring Cribl Edge to Output to Splunk Destinations
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From the top nav, click Manage, then select a Fleet to configure. Next, you have two options:

To configure via the graphical QuickConnect UI, click Routing > QuickConnect (Stream) or Collect (Edge). Next, click + Add Destination at right. From the resulting drawer’s tiles or the Destinations left nav, select Splunk > Single Instance. Next, click either + Add Destination or (if displayed) Select Existing. The resulting drawer will provide the options below.

Or, to configure via the Routing UI, click Data > Destinations (Stream) or More > Destinations (Edge). From the resulting page’s tiles, select Splunk > Single Instance. Next, click New Destination to open a New Destination modal that provides the options below.

General Settings
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Output ID: Enter a unique name to identify this Splunk Single Instance definition.

Address: Hostname of the Splunk receiver.

Port: The port number on the host.

Optional Settings
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Backpressure behavior: Select whether to block, drop, or queue events when all receivers are exerting backpressure. (Causes might include a broken or denied connection, or a rate limiter.) Defaults to Block.

Tags: Optionally, add tags that you can use for filtering and grouping at the final destination. Use a tab or hard return between (arbitrary) tag names.

Persistent Queue Settings
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This tab is displayed when the Backpressure behavior is set to Persistent Queue.

On Cribl-managed Cribl.Cloud Workers (with an Enterprise plan), this tab exposes only the Clear Persistent Queue button. A maximum queue size of 1 GB disk space is automatically allocated per Worker Process.

Max file size: The maximum data volume to store in each queue file before closing it. Enter a numeral with units of KB, MB, etc. Defaults to 1 MB.

Max queue size: The maximum amount of disk space the queue is allowed to consume. Once this limit is reached, Cribl Edge stops queueing and applies the fallback Queue‑full behavior. Enter a numeral with units of KB, MB, etc.

Queue file path: The location for the persistent queue files. Defaults to $CRIBL_HOME/state/queues. To this value, Cribl Edge will append /<worker‑id>/<output‑id>.

Compression: Codec to use to compress the persisted data, once a file is closed. Defaults to None; Gzip is also available.

Queue-full behavior: Whether to block or drop events when the queue is exerting backpressure (because disk is low or at full capacity). Block is the same behavior as non-PQ blocking, corresponding to the Block option on the Backpressure behavior drop-down. Drop new data drops the newest events from being sent out of Cribl Edge, and throws away incoming data, while leaving the contents of the PQ unchanged.

Clear persistent queue: Click this button if you want to flush out files that are currently queued for delivery to this Destination. A confirmation modal will appear. (Appears only after Output ID has been defined.)

TLS Settings (Client Side)
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Enabled defaults to No. When toggled to Yes:

Validate server certs: Reject certificates that are not authorized by a CA in the CA certificate path, or by another trusted CA (e.g., the system’s CA). Defaults to No.

Server name (SNI): Server name for the SNI (Server Name Indication) TLS extension. This must be a host name, not an IP address.

Minimum TLS version: Optionally, select the minimum TLS version to use when connecting.

Maximum TLS version: Optionally, select the maximum TLS version to use when connecting.

Certificate name: The name of the predefined certificate.

CA certificate path: Path on client containing CA certificates (in PEM format) to use to verify the server’s cert. Path can reference $ENV_VARS.

Private key path (mutual auth): Path on client containing the private key (in PEM format) to use. Path can reference $ENV_VARS. Use only if mutual auth is required.

Certificate path (mutual auth): Path on client containing certificates in (PEM format) to use. Path can reference $ENV_VARS. Use only if mutual auth is required.

Passphrase: Passphrase to use to decrypt private key.

Single .pem File
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If you have a single .pem file containing cacert, key, and cert sections, enter it in all of these fields above: CA certificate path, Private key path (mutual auth), and Certificate path (mutual auth).

Timeout Settings
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Connection timeout: Amount of time (in milliseconds) to wait for the connection to establish, before retrying. Defaults to 10000.

Write timeout: Amount of time (in milliseconds) to wait for a write to complete, before assuming connection is dead. Defaults to 60000.

Processing Settings
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Post‑Processing
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Pipeline: Pipeline to process data before sending the data out using this output.

System fields: A list of fields to automatically add to events that use this output. By default, includes cribl_pipe (identifying the Cribl Edge Pipeline that processed the event). Supports wildcards. Other options include:

  • cribl_host – Cribl Edge Node that processed the event.
  • cribl_wp – Cribl Edge Worker Process that processed the event.
  • cribl_input – Cribl Edge Source that processed the event.
  • cribl_output – Cribl Edge Destination that processed the event.

Advanced Settings
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Output multiple metrics: Toggle to Yes to output multiple-measurement metric data points. (Supported in Splunk 8.0 and above, this format enables sending multiple metrics in a single event, improving the efficiency of your Splunk capacity.)

Minimize in-flight data loss: If set to Yes (the default), Cribl Edge will check whether the indexer is shutting down, and if so, will stop sending data. This helps minimize data loss during shutdown. (Note that Splunk logs will indicate that the Cribl app has set UseAck to true, even though Cribl does not enable full UseAck behavior.)

Max S2S version: The highest version of the Splunk-to-Splunk protocol to expose during handshake. Defaults to v3; v4 is also available.

Throttling: Throttle rate, in bytes per second. Defaults to 0, meaning no throttling. Multiple-byte units such as KB, MB, GB etc. are also allowed, e.g., 42 MB. When throttling is engaged, your Backpressure behavior selection determines whether Cribl Edge will handle excess data by blocking it, dropping it, or queueing it to disk.

Nested field serialization: Specifies how to serialize nested fields into index-time fields. Defaults to None.

Authentication method: Use the buttons to select one of these options:

  • Manual: In the resulting Auth token field, enter the shared secret token to use when establishing a connection to a Splunk indexer.

  • Secret: This option exposes an Auth token (text secret) drop-down, in which you can select a stored secret that references the auth token described above. A Create link is available to store a new, reusable secret.

Environment: If you’re using GitOps, optionally use this field to specify a single Git branch on which to enable this configuration. If empty, the config will be enabled everywhere.

Notes about Forwarding to Splunk
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  • Data sent to Splunk is not compressed.
  • The only ack from indexers that Cribl Edge listens for and acts upon is the shutdown signal described in Minimize in-flight data loss above.

  • If events have a Cribl Edge internal field called __criblMetrics, they’ll be forwarded to Splunk as metric events.

  • If events do not have a _raw field, they’ll be serialized to JSON prior to sending to Splunk.

  • See Splunk’s documentation on editing fields.conf to ensure the visibility of index-time fields sent to Splunk by Cribl Edge.