On This Page

Home / Edge/ Functions/Grok

Grok

The Grok Function extracts structured fields from unstructured log data, using modular regex patterns.

Usage
​

Filter: Filter expression (JavaScript) that selects data to feed through the Function. Defaults to true, meaning it evaluates all events.

Description: Optional description of this Function’s purpose in this Pipeline. Defaults to empty.

Final: Toggle on to stop feeding data to the downstream Functions. Default is toggled off.

Pattern: Grok pattern to extract fields. Cick the Expand button at right to open a preview/valdiation modal. Syntax supported: %{PATTERN_NAME:FIELD_NAME}.

Select Add pattern to chain more patterns.

Source field: Field on which to perform Grok extractions. Defaults to _raw.

Management
​

You can add and edit Grok patterns via Cribl Edge’s UI by selecting Knowledge > Grok Patterns. Pattern files are located at: $CRIBL_HOME/(default|local)/cribl/grok-patterns/

Example
​

Example event:

{"_raw": "2020-09-16T04:20:42.45+01:00 DEBUG This is a sample debug log message"}

Pattern: %{TIMESTAMP_ISO8601:event_time} %{LOGLEVEL:log_level} %{GREEDYDATA:log_message} Source Field: _raw

Event after extraction:

{"_raw": "2020-09-16T04:20:42.45+01:00 DEBUG This is a sample debug log message",
  "_time": 1600226442.045,
  "event_time": "2020-09-16T04:20:42.45+01:00",
  "log_level": "DEBUG",
  "log_message": "This is a sample debug log message",
}

Note the new fields added to the event: event_time, log_level, and log_message.

References
​