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TCP JSON Source

Cribl Edge can receive newline-delimited JSON data over TCP.

Type: Push | TLS Support: YES | Event Breaker Support: No

Configure Cribl Edge to Receive TCP JSON Data
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Cribl Edge ships with a TCP JSON Source preconfigured to listen on Port 10070. You can clone or directly modify this Source to further configure it, and then enable it.

  1. On the top bar, select Products, and then select Cribl Edge. Under Fleets, select a Fleet. Next, you have two options:
    • To configure via QuickConnect, navigate to Routing > QuickConnect (Stream) or Collect (Edge). Select Add Source and select the Source you want from the list, choosing either Select Existing or Add New.
    • To configure via the Routes, select Data > Sources (Stream) or More > Sources (Edge). Select the Source you want. Next, select Add Source.
  2. Configure the following under General Settings:
    • Input ID: Enter a unique name. The default Source is prefilled with the value in_tcp_json, which can’t be changed via the UI. If you clone this Source, Cribl Edge will add -CLONE to the original Input ID.
    • Description: Optionally, enter a description.
    • Address: Enter hostname/IP to listen for TCP JSON data. For example, localhost or 0.0.0.0.
    • Port: Enter the port number to listen on.
  3. Under Authentication, select an Authentication method from the dropdown:
    • Manual: Use this default option to enter the shared secret that clients must provide in the authToken header field. Exposes an Auth token field for this purpose. (If left blank, unauthenticated access will be permitted.) A Generate link is available if you need a new secret.
    • Secret: This option exposes an Auth token (text secret) drop-down, in which you can select a stored secret that references the authToken header field value described above. The secret can reside in Cribl Edge’s internal secrets manager or (if enabled) in an external KMS. A Create link is available if you need a new secret.
  4. Next, you can configure the following Optional Settings:
    • Tags: Optionally, add tags that you can use to filter and group Sources in Cribl Edge’s UI. These tags aren’t added to processed events. Use a tab or hard return between (arbitrary) tag names.
  5. Optionally, you can adjust the TLS, Persistent Queue Settings, Processing and Advanced settings, or Connected Destinations outlined in the sections below.
  6. Select Save, then Commit & Deploy.

TLS Settings (Server Side)
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Enabled: Defaults to toggled off. When toggled on:

Certificate name: Name of the predefined certificate.

Private key path: Server path containing the private key (in PEM format) to use. Path can reference $ENV_VARS.

Passphrase: Passphrase to use to decrypt private key.

Certificate path: Server path containing certificates (in PEM format) to use. Path can reference $ENV_VARS.

CA certificate path: Server path containing CA certificates (in PEM format) to use. Path can reference $ENV_VARS.

Authenticate client (mutual auth): Require clients to present their certificates. Used to perform mutual authentication using SSL certs. Default is toggled off. When toggled on:

  • Validate client certs: Reject certificates that are not authorized by a CA in the CA certificate path, or by another trusted CA (for example, the system’s CA). Default is toggled on.

  • Common Name: Regex that a peer certificate’s subject attribute must match in order to connect. Defaults to .*. Matches on the substring after CN=. As needed, escape regex tokens to match literal characters. (For example, to match the subject CN=worker.cribl.local, you would enter: worker\.cribl\.local.) If the subject attribute contains Subject Alternative Name (SAN) entries, the Source will check the regex against all of those but ignore the Common Name (CN) entry (if any). If the certificate has no SAN extension, the Source will check the regex against the single name in the CN.

Minimum TLS version: Optionally, select the minimum TLS version to accept from connections.

Maximum TLS version: Optionally, select the maximum TLS version to accept from connections.

Persistent Queue Settings
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In the Persistent Queue Settings tab, you can optionally specify persistent queue storage, using the following controls. Persistent queue buffers and preserves incoming events when a downstream Destination has an outage or experiences backpressure.

Before enabling persistent queue, learn more about persistent queue behavior and how to optimize it with your system:

On Cribl-managed Cloud Workers (with an Enterprise plan), this tab exposes only the Enable Persistent Queue toggle. If enabled, PQ is automatically configured in Always On mode, with a maximum queue size of 1 GB disk space allocated per PQ‑enabled Source, per Worker Process.

The 1 GB limit is on uncompressed inbound data, and the queue does not perform any compression. This limit is not configurable. For configurable queue size, compression, mode, and other options below, use a hybrid Group.

Enable Persistent Queue: Default is toggled off. When toggled on:

Mode: Select a condition for engaging persistent queues.

  • Always On: This default option will always write events to the persistent queue, before forwarding them to the Cribl Stream data processing engine.
  • Smart: This option will engage PQ only when the Source detects backpressure from the Cribl Stream data processing engine.

Smart mode only engages when necessary, such as when a downstream Destination becomes blocked and the Max buffer size reaches its limit. When persistent queue is set to Smart mode, Cribl attempts to flush the queue when every new event arrives. The only time events stay in the buffer is when a downstream Destination becomes blocked.

Max buffer size: The maximum number of events to hold in memory before reporting backpressure to the sender and writing the queue to disk. Defaults to 1000. This buffer is for all connections, not just per Worker Process. For that reason, this can dramatically expand memory usage. Connections share this limit, which may result in slightly lower throughput for higher numbers of connections. For higher numbers of connections, consider increasing the limit.

Commit frequency: The number of events to send downstream before committing that Stream has read them. Defaults to 42.

Max file size: The maximum data volume to store in each queue file before closing it and (optionally) applying the configured Compression. Enter a numeral with units of KB, MB, and so forth. If not specified, Cribl Stream applies the default 1 MB.

Max queue size: The maximum amount of disk space that the queue is allowed to consume on each Worker Process. Once this limit is reached, this Source will stop queueing data and block incoming data. Required, and defaults to 5 GB. Accepts positive numbers with units of KB, MB, GB, and so forth. Can be set as high as 1 TB, unless you’ve configured a different Worker Process PQ size limit in Group/Fleet settings.

Queue file path: The location for the persistent queue files. Defaults to $CRIBL_HOME/state/queues. To this field’s specified path, Cribl Stream will append /<worker-id>/inputs/<input-id>.

Compression: Optional codec to compress the persisted data after a file closes. Defaults to None; Gzip is also available.

In Cribl Stream 4.1 and later, the Source persistent queue default Mode is Always on, to best ensure events’ delivery. For details on optimizing this selection, see Optimize Source Persistent Queues (sPQ).

You can optimize Workers’ startup connections and CPU load at Group/Fleet settings > Worker Processes.

Processing Settings
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Fields
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In this section, you can add Fields to each event, using Eval-like functionality.

Name: Field name.

Value: JavaScript expression to compute field’s value, enclosed in quotes or backticks. (Can evaluate to a constant.)

Pre-Processing
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In this section’s Pipeline drop-down list, you can select a single existing Pipeline or Pack to process data from this input before the data is sent through the Routes.

Advanced Settings
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Enable proxy protocol: Toggle on if the connection is proxied by a device that supports proxy protocol v1 or v2.

Enable load balancing (Cribl Stream only): Toggle on to distribute the data from incoming TCP connections across multiple Worker Processes. This improves performance compared to the default of having all data from an incoming connection processed on a single Worker Process.

  • This spins up an extra Worker Process (named wLB in Settings > Processes) on the Worker Node, which handles splitting data from incoming TCP connections across all other Worker Processes.
  • When enabled, the option to include common fields in the JSON header is not supported. This means fields specified under fields in the JSON header are not automatically added to all events.

Load balancing is available only in Cribl Stream Distributed deployments.

IP allowlist regex: Regex matching IP addresses that are allowed to establish a connection. Defaults to .* (such as, all IPs).

Max active connections: Maximum number of active connections allowed per Worker Process. Defaults to 1000. Set a lower value if connection storms are causing the Source to hang. Set to 0 for unlimited connections.

Socket idle timeout (seconds): The duration that Cribl Edge will wait for activity on an idle TCP socket before closing the connection. Disabled when set to 0, the default.

Forced socket termination timeout (seconds): The extra time the server waits before forcibly closing a socket that has been idle (TCP socket idle timeout) or exceeded its maximum lifespan (TCP socket max lifespan) but has not yet properly closed. This prevents resource leaks caused by unresponsive clients or network issues. Configure based on network latency and client behavior. Default: 30 seconds. Set to 0 to disable.

Socket max lifespan (seconds): The duration that a socket is allowed to remain open, regardless of activity. This setting prevents resource exhaustion (such as TCP pinning) by limiting the lifespan of connections. Configure based on expected connection durations and resource availability. Disabled when set to 0, the default.

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 configuration will be enabled everywhere.

Connected Destinations
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Select Send to Routes to enable conditional routing, filtering, and cloning of this Source’s data via the Routing table.

Select QuickConnect to send this Source’s data to one or more Destinations via independent, direct connections.

Internal Fields
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Cribl Edge uses a set of internal fields to assist in handling of data. These “meta” fields are not part of an event, but they are accessible, and Functions can use them to make processing decisions.

Field for this Source:

  • __inputId
  • __srcIpPort

Format
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Cribl Edge expects TCP JSON events in newline-delimited JSON format:

  1. A header line. Can be empty – for example, {}. If authToken is enabled (see above) it should be included here as a field called authToken. When authToken is not set, the header line is optional. In this case, the first line will be treated as an event if does not look like a header record.

In addition, if events need to contain common fields, they can be included here under fields. In the example below, region and AZ will be automatically added to all events.

  1. A JSON event/record per line.
Sample TCP JSON Events
{"authToken":"myToken42", "fields": {"region": "us-east-1", "AZ":"az1"}}

{"_raw":"this is a sample event ", "host":"myHost", "source":"mySource", "fieldA":"valueA", "fieldB":"valueB"}
{"host":"myOtherHost", "source":"myOtherSource", "_raw": "{\"message\":\"Something informative happened\", \"severity\":\"INFO\"}"}

TCP JSON Field Mapping to Splunk
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If a TCP JSON Source is routed to a Splunk destination, fields within the JSON payload are mapped to Splunk fields. Fields that do not have corresponding (native) Splunk fields become index-time fields. For example, let’s assume we have a TCP JSON event as below:

{"_time":1541280341, "host":"myHost", "source":"mySource", "_raw":"this is a sample event ", "fieldA":"valueA"}

Here, _time, host, and source become their corresponding fields in Splunk. The value of _raw becomes the actual body of the event, and fieldA becomes an index-time field (fieldA::`valueA``).

Examples
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Testing TCP JSON In
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This first example simply tests that data is flowing in through the Source:

  1. Configure Cribl Edge to listen on port 10001 for TCP JSON. Set authToken to myToken42.
  2. Create a file called test.json with the payload above.
  3. Send it over to your Cribl Edge host: cat test.json | nc <myCriblHost> 10001

Cribl Edge to Cribl.Cloud
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This second example demonstrates using TCP JSON to send data from one Cribl Edge instance to a downstream Cribl.Cloud instance. We assume that the downstream Cloud instance uses Cribl.Cloud’s default TCP JSON Source configuration.

So all the configuration happens on the upstream instance’s TCP JSON Destination. Replace the <Your-Org-ID> placeholder with the Org ID from your Cribl.Cloud portal.

TCP JSON Destination Configuration
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On the upstream Cribl Edge instance’s Destination, set the following field values to match the target Cloud instance’s defaults:

General Settings
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Address: default.main.<Your-Org-ID>.cribl.cloud – you can simply copy/paste your Cribl.Cloud portal’s Ingest Endpoint here. With a Cribl.Cloud Enterprise plan, generalize the default.main substring in this URL to <group-name>.main when sending to other Fleets.

Port: 10070

TLS Settings (Client Side)
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Enabled: Toggle on

Validate server certs: Toggle on

Periodic Logging
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Cribl Edge logs metrics about incoming requests and ingested events once per minute.

These logs are stored in the metrics.log file. To view them in the UI, open the Source’s Logs tab and choose Worker Process X Metrics from the drop-down, where X is the desired Worker Process.

This kind of periodic logging helps you determine whether a Source is in fact still healthy even when no data is coming in.

Troubleshooting
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The Source’s configuration modal has helpful tabs for troubleshooting:

Live Data: Try capturing live data to see real-time events as they are ingested. On the Live Data tab, click Start Capture to begin viewing real-time data.

Logs: Review and search the logs that provide detailed information about the ingestion process, including any errors or warnings that may have occurred.

You can also view the Monitoring page that provides a comprehensive overview of data volume and rate, helping you identify ingestion issues. Analyze the graphs showing events and bytes in/out over time.