logger

Produces structured request/response log entries with method, URL, client IP, request ID, status code, and duration. Sensitive headers are automatically redacted. Place first in the pipeline so every subsequent middleware has a request ID available.

Pipeline stage: Negotiation (first middleware)

Import

import { logger } from "@centralping/ergo";

Options

Option	Type	Default	Description
log	function	console.log	Log function for completed requests
error	function	console.error	Log function for errors
uuid	function	crypto.randomUUID	Fallback UUID generator
headerRequestIdName	string	'x-request-id'	Request ID header name
headerRequestIpName	string	'x-real-ip'	Client IP header name
redactHeaders	Set<string>	See below	Headers replaced with '[REDACTED]'

Default Redacted Headers

authorization, proxy-authorization, cookie, set-cookie

Request ID Resolution Order

1. res.getHeader(headerRequestIdName) — set by ergo-router’s transport
2. req.headers[headerRequestIdName] — set by upstream proxy
3. uuid() — generated as fallback

Return Value

Returns a log entry stored at acc.log:

{
  requestId: "550e8400-e29b-41d4-a716-446655440000",
  timestamp: 1717041600000,
  ip: "127.0.0.1",
  method: "GET",
  url: "/users",
  httpVersion: "1.1",
  host: { hostname, arch, platform, pid },
  request: { headers, encrypted, remoteAddress, remotePort }
}

On response finish, the log callback adds statusCode, duration, and response: { headers, statusMessage, writableFinished }.

Error Responses

None. Logger is observability-only.

Usage

Standalone

import { compose, logger } from "@centralping/ergo";

const pipeline = compose(
  [logger({
    log: (info) => structuredLog.info(info),
    error: (info) => structuredLog.error(info),
  }), "log"],
);

ergo-router

const router = createRouter({
  defaults: {
    logger: {
      log: (info) => structuredLog.info(info),
    },
  },
});

Related Recipes

• Structured Logging — Integrating pino or winston with the log callback and graceful() lifecycle logger

API Reference

See the auto-generated logger API docs.