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Webhook

Cribl Edge can send log and metric events to webhooks and other generic HTTP endpoints.

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

Configuring Cribl Edge to Output via HTTP
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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, select Webhook. 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 or the Destinations left nav, select Webhook. Next, click Add 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 HTTP output definition.

URL: Endpoint URL to send events to. The internal field __url, where present in events, will override this value. See Internal Fields below.

Method: The HTTP verb to use when sending events. Defaults to POST. Change this to PUT or PATCH where required by the endpoint.

Format: The format in which to send out events. One of:

  • NDJSON (newline-delimited JSON): The default.
  • JSON Array: Arrays in JSON-parseable format.
  • Custom: A wrapper object that contains batched events. You define the format for both the wrapper and the individual event. See Custom Format below.

Backpressure behavior: Whether to block, drop, or queue events when all receivers are exerting backpressure.

Tags: Optionally, add tags that you can use to filter and group Destinations in Cribl Edge’s Manage Destinations page. These tags aren’t added to processed events. Use a tab or hard return between (arbitrary) tag names.

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

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.

Authentication
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Select one of the following options for authentication:

  • None: Don’t use authentication.

  • Auth token: Use HTTP token authentication. In the resulting Token field, enter the bearer token that must be included in the HTTP authorization header.

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

  • Basic: Displays Username and Password fields for you to enter HTTP Basic authentication credentials.

  • Basic (credentials secret): This option exposes a Credentials secret drop-down, in which you can select a stored text secret that references the Basic authentication credentials described above. A Create link is available to store a new, reusable secret.

  • OAuth: Configure authentication via the OAuth protocol. Exposes multiple extra options – see OAuth Authentication below.

OAuth Authentication
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Selecting OAuth exposes the following additional fields:

  • Login URL: Endpoint for the OAuth API call, which is expected to be a POST call.

  • OAuth secret: Secret parameter value to pass in the API call’s request body.

  • OAuth secret parameter name: Secret parameter name to pass in API call’s request body.

  • Token attribute name: Name of the auth token attribute in the OAuth response. Can be top-level (e.g., token); or nested, using a period (e.g., data.token).

  • Authorize expression: JavaScript expression used to compute the Authorization header to pass in requests. Uses ${token} to reference the token obtained from the login POST request, e.g.: `Bearer ${token}`.

  • Refresh interval (secs.): How often to refresh the OAuth token. Default 3600 seconds (1 hour); minimum 1 second; maximum 300000 seconds (about 83 hours).

  • OAuth parameters: Optionally, click Add parameter for each additional parameter you want to send in the OAuth login request. Cribl Edge will combine the secret with these parameters, and will send the URL-encoded result in a POST request to the endpoint specified in the Login URL. We’ll automatically add the Content‑Type header application/x‑www‑form‑urlencoded when sending this request.

    In each row of the resulting table, enter the parameter’s Name. The corresponding Value is a JavaScript expression to compute the parameter’s value. This can also evaluate to a constant. Values not formatted as expressions – e.g., id instead of `${id}` – will be evaluated as strings.

  • Authentication headers: Optionally, click Add Header for each custom auth header you want to define and send in the OAuth login request. Stream will automatically add the Content‑Type header application/x‑www‑form‑urlencoded when sending this request.

    In each row of the resulting table, enter the custom OAuth header’s Name. The corresponding Value is a JavaScript expression to compute the header’s value. This can also evaluate to a constant. Values not formatted as expressions – e.g., id instead of `${id}` – will be evaluated as strings.

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. If the queue fills up, Cribl Edge will block outbound data.

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 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.)

Strict ordering: The default Yes position enables FIFO (first in, first out) event forwarding. When receivers recover, Cribl Edge will send earlier queued events before forwarding newly arrived events. To instead prioritize new events before draining the queue, toggle this off. Doing so will expose this additional control:

  • Drain rate limit (EPS): Optionally, set a throttling rate (in events per second) on writing from the queue to receivers. (The default 0 value disables throttling.) Throttling the queue’s drain rate can boost the throughput of new/active connections, by reserving more resources for them. You can further optimize Workers’ startup connections and CPU load at Fleet Settings > Worker Processes.

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_input – Cribl Edge Source that processed the event.
  • cribl_output – Cribl Edge Destination that processed the event.
  • cribl_route – Cribl Edge Route (or QuickConnect) that processed the event.
  • cribl_wp – Cribl Edge Worker Process that processed the event.

Advanced Settings
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Validate server certs: Reject certificates that are not authorized by a CA in the CA certificate path, nor by another trusted CA (e.g., the system’s CA). Defaults to Yes.

Round-robin DNS: Toggle on to enable round-robin DNS lookup across multiple IP addresses, IPv4 and IPv6. When a DNS server resolves a Fully Qualified Domain Name (FQDN) to multiple IP addresses, Cribl Edge will sequentially use each address in the order they are returned by the DNS server for subsequent connection attempts.

Compress: Compresses the payload body before sending. Defaults to Yes (recommended).

Keep alive: By default, Cribl Edge sends Keep-Alive headers to the remote server and preserves the connection from the client side up to a maximum of 120 seconds. Toggle this off if you want Cribl Edge to close the connection immediately after sending a request.

Request timeout: Amount of time (in seconds) to wait for a request to complete before aborting it. Defaults to 30.

Request concurrency: Maximum number of concurrent requests per Worker Process. When Cribl Edge hits this limit, it begins throttling traffic to the downstream service. Defaults to 5. Minimum: 1. Maximum: 32.

Max body size (KB): Maximum size of the request body before compression. Defaults to 4096 KB. You can set this limit to as high as 500 MB (512000 KB). Be aware that high values can cause high memory usage per Worker Node, especially if a dynamically constructed URL (see Internal Fields) causes this Destination to send events to more than one URL. The actual request body size might exceed the specified value because the Destination adds bytes when it writes to the downstream receiver. Cribl recommends that you experiment with the Max body size value until downstream receivers reliably accept all events.

Max events per request: Maximum number of events to include in the request body. The 0 default allows unlimited events.

Flush period (sec): Maximum time between requests. Low values could cause the payload size to be smaller than its configured maximum. Defaults to 1.

Extra HTTP headers: Name-value pairs to pass to all events as additional HTTP headers. Values will be sent encrypted. You can also add headers dynamically on a per-event basis in the __headers field. See Internal Fields below.

Failed request logging mode: Use this drop-down to determine which data should be logged when a request fails. Select among None (the default), Payload, or Payload + Headers. With this last option, Cribl Edge will redact all headers, except non-sensitive headers that you declare below in Safe headers.

Safe headers: Add headers to declare them as safe to log in plaintext. (Sensitive headers such as authorization will always be redacted, even if listed here.) Use a tab or hard return to separate header names.

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.

Custom Format
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Choosing Custom from the General Settings > Format drop-down exposes the additional fields described in this section. Source expression and most of the rest of the controls define the format of individual events, i.e., what data you want to make available from the event. Batch expression defines the wrapper object for batched events, i.e., how to package events within the request payload. Both expressions must be enclosed in backticks.

  • Source expression: JavaScript expression to evaluate on every event; Cribl Edge will send the result of that evaluation instead of the original event. Sample expression: `${fieldA}, ${fieldB}` (with literal backticks). Defaults to __httpOut – i.e., the value of the __httpOut field. Use the button at right to open a validation modal.

  • Drop when null: If toggled to Yes, Cribl Edge will drop events when the Source expression evaluates to null.

  • Event delimiter: Delimiter string to insert between events. Defaults to the newline character (\n). Cannot be a space (this will be converted to \n).

  • Content type: Content type to use for requests. Defaults to application/x‑ndjson. Any content types set in Advanced Settings > Extra HTTP headers will override this entry.

  • Batch expression: Expression specifying how to format the payload for each batch. Defines a wrapper object in which to include the formatted events, such as a JSON document. This enables requests to APIs that require such objects. To reference the events to send, use the ${events} variable. An example expression to send the batch inside a JSON object would be: {"items" : [${events}] }.

Custom Format Example
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Suppose that the API you’re sending events to requires request payloads in the following form:

{
   "Events":[
      {
         "one":"1",
         "two":"2"
      },
      {
         "one":"1.1",
         "two":"2.2"
      }
   ]
}

And here’s how the events coming into your Webhook Destination look – note that the field names need to change, and field3 and field4 need to be dropped:

{ "field1": 1, "field2": 2, "field3": 3, "field4": 4 }
{ "field1": 1.1, "field2": 2.2, "field3": 3.3, "field4": 4.4 }

To send these events in the required form, you’d do the following:

  • Set the Source expression to `{ "one": "${field1}", "two": "${field2}" }` – note that this renames and sends only the desired fields (one and two).
  • Enter the comma (,) as your Event delimiter.
  • Set the Batch expression to `{ "Events": [${events}] }`.

Internal Fields
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Cribl Edge uses a set of internal fields to assist in forwarding data to a Destination.

Fields for this Destination:

  • __criblMetrics
  • __url
  • __headers

If an event contains the internal field __criblMetrics, Cribl Edge will send it to the HTTP endpoint as a metric event. Otherwise, Cribl Edge will send it as a log event.

If an event contains the internal field __url, that field’s value will override the General Settings > URL value. This way, you can determine the endpoint URL dynamically.

For example, you could create a Pipeline containing an Eval Function that adds the __url field, and connect that Pipeline to your Webhook Destination. Configure the Eval Function to set __url’s value to a URL that varies depending on a global variable, or on some property of the event, or on some other dynamically-generated value that meets your needs.

If an event contains the internal field __headers, that field’s value will be a JSON object containing Name-value pairs, each of which defines a header. By creating Pipelines that set the value of __headers according to conditions that you specify, you can add headers dynamically.

For example, you could create a Pipeline containing Eval Functions that add the __headers field, and connect that Pipeline to your Webhook Destination. Configure the Eval Functions to set __headers values to Name-value pairs that vary depending on some properties of the event, or on dynamically-generated values that meet your needs.

Here’s an overview of how to add headers:

  • To add “dynamic” (a.k.a. “custom”) headers to some events but not others, use the __headers field.
  • To define headers to add to all events, use Advanced Settings > Extra HTTP Headers.
  • An event can include headers added by both methods. So if you use __headers to add { "api‑key": "foo" } and Extra HTTP Headers to add { "goat": "Kid A" }, you’ll get both headers.
  • Headers added via the __headers field take precedence. So if you use __headers to add { "api‑key": "foo" } and Extra HTTP Headers to add { "api‑key": "bar" }, you’ll get only one header, and that will be { "api‑key": "foo" }.

Use Cases
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See these examples of configuring a Webhook Destination to integrate with specific services:

Notes on HTTP-Based Outputs
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  • To proxy outbound HTTP/S requests, see System Proxy Configuration.

  • Cribl Edge will attempt to use keepalives to reuse a connection for multiple requests. After two minutes of the first use, it will throw away the connection and attempt a new one. This is to prevent sticking to a particular destination when there is a constant flow of events.

  • If the server does not support keepalives (or if the server closes a pooled connection while idle), Cribl Edge will establish a new connection for the next request.

  • When resolving the Destination’s hostname, Cribl Edge will pick the first IP in the list for use in the next connection. Enable Round‑robin DNS to better balance distribution of events among destination cluster nodes.