Elasticsearch

Cribl Stream can send events to an Elasticsearch cluster using the Bulk API. As of v.3.3, Cribl Stream supports Elastic data streams.

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

Configuring Cribl Stream to Output to Elasticsearch​

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 Elasticsearch. 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 Elasticsearch. 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 Elasticsearch Destination definition. If you clone this Destination, Cribl Stream will add -CLONE to the original Output ID.

Load balancing: When enabled (default), lets you specify multiple bulk API URLs and load weights. With the No setting, if you notice that Cribl Stream is not sending data to all possible IP addresses, enable Advanced Settings > Round-robin DNS.

Bulk API URL or Cloud ID: Specify either an Elasticsearch cluster or Elastic Cloud deployment to send events to. For an Elasticsearch cluster, enter a URL (e.g., http://<myElasticCluster>:9200/_bulk). For an Elastic Cloud deployment, enter its Cloud ID. This setting is not available when Load balancing is enabled.

Bulk API URLs​

Use the Bulk API URLs table to specify a known set of receivers on which to load-balance data. To specify more receivers on new rows, click Add URL. Each row provides the following fields:

URL: Specify the URL to an Elastic node to send events to – e.g., http://elastic:9200/_bulk

Load weight: Set the relative traffic-handling capability for each connection by assigning a weight (> 0). This column accepts arbitrary values, but for best results, assign weights in the same order of magnitude to all connections. Cribl Stream will attempt to distribute traffic to the connections according to their relative weights.

The final column provides an X button to delete any row from the table.

For details on configuring all these options, see About Load Balancing.

When you first enable load balancing, or if you edit the load weight once your data is load–balanced, give the logic time to settle. The changes might take a few seconds to register.

Index or data stream: Enter a JavaScript expression that evaluates to the name of the Elastic data stream or Elastic index where you want events to go. The expression is evaluated for each event, can evaluate to a constant value, and must be enclosed in quotes or backticks. An event’s __index field can overwrite the index or data stream name.

Authentication Settings​

Authentication enabled: When toggled to Yes, use the Authentication method buttons to select one of these options:

Manual: Enter your credentials directly in the resulting Username and Password fields.

Secret: Exposes a Credentials secret drop-down, in which you can select a stored secret that references the credentials described above. A Create link is available to store a new, reusable secret.

Manual API Key: Exposes an API key field to directly enter your Elasticsearch API key.

Secret API Key: Exposes an API key (text secret) drop-down, in which you can select a stored text secret that references your Elasticsearch API key. A Create link is available to store a new, reusable secret.

Optional Settings​

Exclude current host IPs: This toggle appears when Load balancing is set to Yes. It determines whether to exclude all IPs of the current host from the list of any resolved hostnames. Defaults to No, which keeps the current host available for load balancing.

Type: Specify document type to use for events. An event’s __type field can overwrite this value.

Backpressure behavior: Specify whether to block, drop, or queue events when all receivers are exerting backpressure. Defaults to Block.

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.

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 that the queue is allowed to consume on each Worker Process. Once this limit is reached, this Destination will stop queueing data and apply the Queue‑full behavior. 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. Cribl Stream will append /<worker‑id>/<output‑id> to this field’s value.

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. By default, includes cribl_pipe (identifying the Cribl Stream Pipeline that processed the event). Supports wildcards. 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​

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:

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​

Validate server certs: Reject certificates that are not authorized by a trusted CA (e.g., the system’s CA). Defaults to Yes.

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. (This option is visible only when the General Settings > Load balancing option is set to No.)

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

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 Stream 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. 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 (s): 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 as additional HTTP headers. Values will be sent encrypted.

Extra parameters: Name-value pairs to pass as additional parameters. If you are using Elastic ingest pipelines, specify an extra parameter whose name is pipeline and whose value is the name of your pipeline, similar to these examples.

Elastic version: Determines how to format events. For Elastic Cloud, you must explicitly set version 7.x. For other Elasticsearch clusters, the Auto default will discover the downstream Elasticsearch version automatically, but you have the option to explicitly set version 6.x or 7.x.

Elastic pipeline: To send data to an Elastic Ingest pipeline, optionally enter that pipeline’s name as a constant. Or, enter a JavaScript expression that evaluates outgoing events and sends matching events to the desired Elastic Ingest pipeline(s). Cribl Stream will first interpret your entry as a constant and try to find a matching value in the event. If it finds no matching value, it will evaluate your Elastic pipeline entry as an expression.

For example, the expression sourcetype=='access_common'?'cribl_pipeline':undefined matches events whose sourcetype is access_common, and sends them to an Elastic Ingest pipeline named cribl_pipeline.

You can also specify the name of the pipeline in an event field. For example, myPipelineField would use the value from the event’s myPipelineField property (if present) to identify the Elastic Ingest pipeline to process the event. Alternately, the expression myPipelineField != null ? myPipelineField : undefined would also identify this field. If the event does not contain such a field, myPipelineField != null ? myPipelineField : 'theDefaultIndex' will provide a default index. With this approach, you can override the Elastic Ingest pipeline at the event level.

See also the Elasticsearch Source documentation.

The next two fields appear only when the General Settings > Load balancing option is set to Yes.

DNS resolution period (seconds): Re-resolve any hostnames each time this interval recurs, and pick up destinations from the A records. Defaults to 600 seconds.

Load balance stats period (seconds): Lookback traffic history period. Defaults to 300 seconds.

Include document_id: Toggle this setting to No to omit the document_id field when sending events to an Elastic TSDS (time series data stream).

Write action: Action to use when writing events. Set this option to Create (default) when writing to a data stream, which is append-only. Set this option to Index only when you write directly to an index and need to update existing records. Index will fail if you use it to write to a data stream.

Failed request logging mode: Determines which data is logged when a request fails. Use the drop-down to select one of these options:

• None (default).
• Payload.
• Payload + Headers. Use the Safe Headers field below to specify the headers to log. If you leave that field empty, all headers are redacted, even with this setting.

Safe headers: List the headers you want to log, in plain text.

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.

Field Normalization​

This Destination normalizes the following fields:

• _time becomes @timestamp at millisecond resolultion.
• host.name is set to host.

See also our Elasticsearch Source documentation’s Field Normalization section.

Internal Fields​

Cribl Stream uses a set of internal fields to assist in forwarding data to a Destination.

Fields for this Destination:

• __id
• __type
• __index
• __host

Notes on HTTP-Based Outputs​

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

• Cribl Stream will attempt to use keepalives to reuse a connection for multiple requests. After two minutes of the first use, the connection will be thrown away, and a new one will be reattempted. 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), a new connection will be established for the next request.

• When resolving the Destination’s hostname with load balancing disabled, Cribl Stream will pick the first IP in the list for use in the next connection. Enable Round-robin DNS to better balance distribution of events between Elasticsearch cluster nodes.