generateUuid()

The generateUuid() function takes no arguments and returns a randomly generated UUID version 4 string, for example, "550e8400-e29b-41d4-a716-446655440000". Each call produces a unique value using a cryptographically strong random number generator, so collision probability is negligible in practice.

This function is useful when source records do not contain a natural unique identifier—for example, when running asynchronous batch inference jobs that require a stable key to match inference results back to the original records.

Usage

Use generateUuid() as a value_expression in the add_entries processor. This example adds a recordId field containing a unique UUID to every event passing through the processor:

processor:
  - add_entries:
      entries:
        - key: recordId
          value_expression: 'generateUuid()'

Example

The following pipeline assigns a unique recordId to each incoming log record before forwarding it to OpenSearch:

uuid-demo-pipeline:
  source:
    http:
      ssl: false

  processor:
    - add_entries:
        entries:
          - key: recordId
            value_expression: 'generateUuid()'

  sink:
    - opensearch:
        hosts: ["https://opensearch:9200"]
        insecure: true
        username: admin
        password: admin_password
        index_type: custom
        index: demo-index-%{yyyy.MM.dd}

Given the following input event:

{ "message": "user login", "user": "alice" }

The document stored in OpenSearch contains the following information:

{
  "message": "user login",
  "user": "alice",
  "recordId": "550e8400-e29b-41d4-a716-446655440000"
}