Metrics

Cribl Stream supports receiving metrics in these wire formats/protocols: StatsD, StatsD Extended, and Graphite. Automatic protocol detection happens on the first line received over a TCP connection or a UDP packet. Lines not matching the detected protocol are dropped.

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

Cribl Edge Workers support System Metrics only when running on Linux, not on Windows.

Configuring Cribl Stream to Receive Metrics​

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 Source at left. From the resulting drawer’s tiles, select [Push > ] Metrics. 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 > Sources (Stream) or More > Sources (Edge). From the resulting page’s tiles or left nav, select [[Push > ] Metrics. Next, click New Source to open a New Source modal that provides the options below.

General Settings​

Input ID: Enter a unique name to identify this Source definition. If you clone this Source, Cribl Stream will add -CLONE to the original Input ID.

Address: Enter the hostname/IP to listen to. Defaults to 0.0.0.0.

UDP port: Enter the UDP port number to listen on. Not required if listening on TCP.

TCP port: Enter the TCP port number to listen on. Not required if listening on UDP.

Sending large numbers of UDP events per second can cause Cribl.Cloud to drop some of the data. This results from restrictions of the UDP protocol.

To minimize the risk of data loss, deploy a hybrid Stream Worker Group with customer-managed Worker Nodes as close as possible to the UDP senders. Cribl also recommends tuning the OS UDP buffer size.

Optional Settings​

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

TLS Settings (TCP Only)​

Enabled defaults to No. When toggled to Yes:

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. Defaults to No. When toggled to Yes:

  • Validate client 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 Yes.

  • 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​

In this section, you can optionally specify persistent queue storage, using the following controls. This will buffer and preserve incoming events when a downstream Destination is down, or exhibiting backpressure.

On Cribl-managed Cribl.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 no compression is applied to the queue. This limit is not configurable. For configurable queue size, compression, mode, and other options below, use a hybrid Group.

Enable Persistent Queue: Defaults to No. When toggled to Yes:

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 Cribl Stream’s data processing engine.
  • Smart: This option will engage PQ only when the Source detects backpressure from Cribl Stream’s data processing engine.

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 per connection, not just per Worker Process – and this can dramatically expand memory usage.)

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, etc. 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, etc. Can be set as high as 1 TB, unless you’ve configured a different Max PQ size per Worker Process in Group 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 is closed. Defaults to None; Gzip is also available.

In Cribl Stream 4.1 and later, Source-side PQ’s default Mode is Always on, to best ensure events’ delivery. For details on optimizing this selection, see Always On versus Smart Mode.

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

Processing Settings​

Fields​

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​

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

Advanced Settings​

Enable Proxy Protocol: Toggle to Yes if the connection is proxied by a device that supports Proxy Protocol v1 or v2.

IP allowlist regex: Regex matching IP addresses that are allowed to send data. Defaults to .* (i.e., all IPs.)

**Max buffer size (events) **: Maximum number of events to buffer when downstream is blocking. Defaults to 1000.

UDP socket buffer size (bytes): Optionally, set the SO_RCVBUF socket option for the UDP socket. This value tells the operating system how many bytes can be buffered in the kernel before events are dropped. Leave blank to use the OS default. Min: 256. Max: 4294967295.

It may also be necessary to increase the size of the buffer available to the SO_RCVBUF socket option. Consult the documentation for your operating system for a specific procedure.

Setting this value will affect OS memory utilization.

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.

Connected Destinations​

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​

Cribl Stream 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.

Fields for this Source:

  • __srcIpPort
  • __metricsInType

Metric Event Schema and Destination Support​

Metric data is read into the following event schema:

_metric - the metric name
_metric_type - the type of the metric (gauge, counter, timer)
_value - the value of the metric
_time - metric_time or Date.now()/1000
dim1 - value of dimension1
dim2 - value of dimension2
....

Cribl Stream places sufficient information into a field called __criblMetric to enable these events to be properly serialized out to any metric outputs (independent of the input type).

The following Destinations natively support the __criblMetric field:

  • Splunk
  • Splunk HEC
  • InfluxDB
  • Statsd
  • Statsd Extended
  • Graphite

Data Format/​Protocol Examples​

StatsD​

Format: MetricName:value|type

StatsD Example
metric1:100|g
metric2:200|ms
metric.dot.3:300.16|c

See the StatsD repo.

StatsD Extended​

Format: MetricName:value|type|#dim=value,dim2=value

StatsD Extended Example
metric1:100|g|#dim1:val1,dim2:val2,dim3:val3
metric2:200|ms|#dim1:val1,dim2:val2,dim3:val3
metric.dot.3:300.16|c|#dim1:val1,dim2:val2,dim3:val3

Graphite​

Format: MetricName[;dim1=val1[;dim2=val2]] value time

Graphite Example with Dimensions
metric1;dim1=val1;dim2=val2 100 9999
metric2;dim1=val1;dim2=val2 200 9999
metric.dot.3;dim1=val1;dim2=val2 300.16 9999.16
Graphite Example without Dimensions
metric1 100 9999
metric2 200 9999
metric.dot.3 300.16 9999.16

See the Graphite (also known as Carbon) plaintext protocol.