loggerl

Advanced Node.js logger with:

• Daily file logging with per-process file names
• Size-based rotation window (5MB per file, keep last 5 files)
• Optional JSON output via LOG_JSON=true
• Colorized console output (info/warn/error/debug)
• Safe stringify with truncation
• Global console.* patching
• Helpers to capture external child process output and tail third-party log files

Install

npm install loggerl

If you're working from source, install dev deps and build:

npm install
npm run build

Usage

import { logger, captureProcess, captureFile } from 'loggerl';

logger.info('Server started');
logger.warn({ slow: true, ms: 350 });
logger.error(new Error('boom'));
logger.debug('only in development');

// Forward a child process output into the logger
import { spawn } from 'child_process';
const child = spawn('node', ['-v']);
captureProcess(child);

// Periodically ingest a third-party log file
captureFile('/var/log/other-app.log', 2000);

Behavior

• Files are created under ./logs relative to your current working directory.
• Names: app-<pid>-YYYY-MM-DD-<n>.log.
• Rotation: when the active file exceeds 5MB, a new file is created; only the most recent 5 are kept for that day.
• Colorized console output is shown only when not in JSON mode.
• JSON mode: set LOG_JSON=true to write one JSON object per line to the file. Console color output is disabled in this mode.
• Debug level is enabled when NODE_ENV=development.

API

• logger.info|warn|error|debug(message: string | object | number | boolean | null | undefined)
  • Writes to the active log file; also writes colorized line to stdout when not in JSON mode.
• captureProcess(proc: ChildProcess)
  • Pipes proc.stdout as info and proc.stderr as error into the logger.
• captureFile(filePath: string, intervalMs = 5000)
  • Every intervalMs, reads the entire file; if it has content, logs: "Logs de archivo <path>: <content>".

Configuration

• LOG_JSON=true — enable JSON line output (disables colorized console output).
• NODE_ENV=development — enables debug level.

Notes

• The module patches global console.* to write through the logger. If you need to avoid this behavior in certain scripts, import dynamically where needed.
• The log directory is created if missing.

Development

• Build: npm run build
• Test: npm test

# Runs TypeScript build, then executes Jest e2e tests
npm test