OpenTelemetry (OTel)​

Cribl Stream supports sending events to OpenTelemetry Protocol (OTLP)-compliant targets. (Cribl Stream can receive OTel events through the OTel Source.) Besides native OTel Trace and Metric events, you can send Cribl Stream’s Gauge metric events through this OTel Destination.

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

Protocol and Transport Support​

In Cribl Stream 4.1 and later, this Destination supports either of the transports that OTLP specifies: gRPC or HTTP. OTLP defines Protocol buffer (Protobuf) schemas for its payloads (requests and responses). With the HTTP transport, this Destination supports Binary Protobuf payload encoding, but currently does not support JSON Protobuf.

When configuring Pipelines (including pre-processing and post-processing Pipelines), you need to ensure that events sent to this Destination conform to the relevant Protobuf specification:

The OTel Destination will drop non-conforming events. If the Destination encounters a parsing error when trying to convert an event to OTLP, it discards the event and Cribl Stream logs the error.

Configuring Cribl Stream to Output to OTel​

From the top nav, click Manage, then select a Worker Group 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 OpenTelemetry. 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 OpenTelemetry. Next, click Add Destination to open a New Destination modal that provides the options below.

General Settings​

Output ID: Enter a unique name to identify this OTel output definition.

Endpoint: Where to send events, in any of a variety of formats (FQDN, PQDN, IP address and port, etc). Supports both IPv4 and IPv6 – IPv6 addresses must be enclosed in square brackets. The same endpoint is used for both Traces and Metrics. If no port is specified, we normally default to the standard port for OTel Collectors, 4137 – however, if TLS is enabled or the endpoint is an HTTPS-based URL, we default instead to port 443.

To proxy outbound HTTP/S requests, see System Proxy Configuration.

Optional Settings​

Protocol: Use the drop-down to choose the protocol to use when sending data: gRPC (the default), or HTTP. When set to HTTP, the UI add the Retries section (left tab) and displays two additional settings:

  • Traces endpoint override: By default, the Destination will send traces to <endpoint>/v1/traces, where <endpoint> is what you specified for the Endpoint setting above. To send traces to a different endpoint, enter that endpoint here.
  • Metrics endpoint override: By default, the Destination will send traces to <endpoint>/v1/metrics, where <endpoint> is what you specified for the Endpoint setting above. To send metrics to a different endpoint, enter that endpoint here.

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 Stream’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)​

TLS is available only when General Settings > Protocol is set to gRPC.

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, nor by another trusted CA (e.g., the system’s CA). Defaults to Yes.

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​

Select one of the following options for authentication:

  • None: Don’t use authentication.

  • Auth token: Enter the bearer token that must be included in the authorization header. Since OpenTelemetry runs over gRPC, authorization headers are sent as Metadata entries which are essentially key-value pairs. E.g.: Bearer <your-configured-token>.

  • Auth token (text secret): This option exposes a 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: This default option displays 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.

Persistent Queue Settings​

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 destructive Clear Persistent Queue button (described below in this section). A maximum queue size of 1 GB disk space is automatically allocated per PQ‑enabled Destination, per Worker Process. The 1 GB limit is on outbound uncompressed data, and no compression is applied to the queue.

This limit is not configurable. If the queue fills up, Cribl Stream will block outbound data. To configure the queue size, compression, queue-full fallback behavior, and other options below, use a hybrid Group.

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, queueing is stopped and data blocking is applied. Enter a numeral with units of KB, MB, etc.

Queue file path: The location for the persistent queue files. This will be of the form: your/path/here/<worker-id>/<output-id>. Defaults to: $CRIBL_HOME/state/queues.

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 “panic” button if you want to delete the files that are currently queued for delivery to this Destination. A confirmation modal will appear - because this will free up disk space by permanently deleting the queued data, without delivering it to downstream receivers. (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 Stream 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 Group Settings > Worker Processes.

Processing Settings​

Post‑Processing​

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 – both metric events, as dimensions; and log events, as labels. Supports wildcards.

By default, includes cribl_pipe (Cribl Stream Pipeline that processed the event).

Other options include:

  • cribl_host – Cribl Stream Node that processed the event.
  • cribl_input – Cribl Stream Source that processed the event.
  • cribl_output – Cribl Stream Destination that processed the event.
  • cribl_route – Cribl Stream Route (or QuickConnect) that processed the event.
  • cribl_wp – Cribl Stream Worker Process that processed the event.

Retries​

This tab is displayed when General Settings > Optional Settings > Protocol is set to HTTP.

Honor Retry-After header: Whether to honor a Retry-After header, provided that the header specifies a delay no longer than 180 seconds. Cribl Stream limits the delay to 180 seconds even if the Retry-After header specifies a longer delay. When enabled, any Retry-After header received takes precedence over all other options configured in the Retries section. When disabled, all Retry-After headers are ignored.

Settings for failed HTTP requests: When you want to automatically retry requests that receive particular HTTP response status codes, use these settings to list those response codes.

For any HTTP response status codes that are not explicitly configured for retries, Cribl Stream applies the following rules:

Status CodeAction
Greater than or equal to 400 and less than or equal to 500.Drop the request.
Greater than 500.Retry the request.

Upon receiving a response code that’s on the list, Cribl Stream first waits for a set time interval called the Pre-backoff interval and then begins retrying the request. Time between retries increases based on an exponential backoff algorithm whose base is the Backoff multiplier, until the backoff multiplier reaches the Backoff limit (ms). At that point, Cribl Stream continues retrying the request without increasing the time between retries any further.

By default, this Destination has no response codes configured for automatic retries. For each response code you want to add to the list, click Add Setting and configure the following settings:

  • HTTP status code: A response code that indicates a failed request, for example 429 (Too Many Requests) or 503 (Service Unavailable).
  • Pre-backoff interval (ms): The amount of time to wait before beginning retries, in milliseconds. Defaults to 1000 (one second).
  • Backoff multiplier: The base for the exponential backoff algorithm. A value of 2 (the default) means that Cribl Stream will retry after 2 seconds, then 4 seconds, then 8 seconds, and so on.
  • Backoff limit (ms): The maximum backoff interval Cribl Stream should apply for its final retry, in milliseconds. Default (and minimum) is 10,000 (10 seconds); maximum is 180,000 (180 seconds, or 3 minutes).

Retry timed-out HTTP requests: When you want to automatically retry requests that have timed out, toggle this control on to display the following settings for configuring retry behavior:

  • Pre-backoff interval (ms): The amount of time to wait before beginning retries, in milliseconds. Defaults to 1000 (one second).
  • Backoff multiplier: The base for the exponential backoff algorithm. A value of 2 (the default) means that Cribl Stream will retry after 2 seconds, then 4 seconds, then 8 seconds, and so on.
  • Backoff limit (ms): The maximum backoff interval Cribl Stream should apply for its final retry, in milliseconds. Default (and minimum) is 10,000 (10 seconds); maximum is 180,000 (180 seconds, or 3 minutes).

Advanced Settings ​

This tab’s options depend on whether General Settings > Protocol is set to the gRPC or HTTP transport. The common settings directly are displayed for both transports.

Common Settings​

Compression: Compression type to apply to messages sent to the OpenTelemetry endpoint. Gzip (the default) and None are available for both protocols; Deflate is available for gRPC only.

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

Request concurrency: Maximum number of concurrent requests before blocking. This is set per Worker Process. Defaults to 5.

Max body size (KB): Maximum size of the request body before compression. Defaults to 4096 KB. 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.

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

Environment: Optionally, specify a single Git branch on which to enable this configuration. If this field is empty, the config will be enabled everywhere.

Additional Settings for gRPC​

When General Settings > Protocol is set to gRPC, the Advanced Settings tab adds the following options.

Connection timeout: Amount of time (milliseconds) to wait for the connection to establish before retrying. Defaults to 10000 (10 sec.).

Keep alive time (seconds): How often the sender should ping the peer to keep the connection alive. Defaults to 30.

Metadata: Extra information to send with each gRPC request. Click Add Metadata to add each item as a Key-Value pair. The Key field is arbitrary. The Value field is a JavaScript expression that is evaluated just once, when this Destination is initialized. If you pass credentials as metadata, Cribl recommends using C.Secret().

Additional Settings for HTTP​

When General Settings > Protocol is set to HTTP, the Advanced Settings tab adds the following options.

Validate server certs: Toggle to Yes to 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).

Round-robin DNS: Toggle to Yes to use round-robin DNS lookup across multiple IPv6 addresses. When a DNS server returns multiple addresses, this will cause Cribl Stream to cycle through them in the order returned.

Keep alive: By default, Cribl Stream 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 Stream to close the connection immediately after sending a request.

Extra HTTP headers: Click Add Header to define additional HTTP headers to pass to all events. Each row is a Name‑Value pair. Values will be sent encrypted. You can also add headers dynamicall,y on a per-event basis, in the __headers field.

Safe headers: Add headers here 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.