Processors

Processors are useful for redaction, enrichment, normalization, or deriving metadata before a transport sees the record.

import {
  ConsoleTransport,
  CompositeProcessor,
  createNamedLogger,
  DefaultsProcessor,
  PrettyFormatter,
  RedactProcessor,
  Severity,
} from "@jamx/logger";

const logger = createNamedLogger({
  name: "auth",
  minSeverity: Severity.Info,
  processor: new CompositeProcessor([
    new DefaultsProcessor({ source: "auth" }),
    new RedactProcessor(["token"]),
  ]),
  transport: new ConsoleTransport(new PrettyFormatter()),
});

The processor can also be swapped at runtime:

logger.processor = undefined;

Built-In Processors

• CompositeProcessor: runs multiple processors in order.
• DefaultsProcessor: adds default metadata without overwriting existing keys.
• RedactProcessor: replaces values for configured metadata keys without changing field names.
• ErrorProcessor: normalizes Error values in metadata.

RedactProcessor walks nested objects and arrays, preserves circular object graphs safely, and does not mutate the original metadata. Configure every key that may contain sensitive information:

new RedactProcessor(["password", "token", "authorization", "apiKey"]);

Processor failures fall back to the original record. Put redaction before other custom processors when sensitive metadata must be removed before further processing.