@wuyuchentr/log-rotator

Auto-rotate log files by size or time. Supports compression and polling watch. Zero dependencies (uses built-in zlib).

A lightweight logrotate for Node.js apps.

Install

npm install @wuyuchentr/log-rotator

Usage

const { rotateLog, watchLog } = require('@wuyuchentr/log-rotator');

One-shot rotation

const result = await rotateLog('app.log', {
  maxSize: '10MB',
  maxFiles: 5,
  compress: true,
  copytruncate: false,  // default: rename + create empty file
});
// → { rotated: true }

Polling watch

const watcher = watchLog('app.log', {
  maxSize: '10MB',
  maxFiles: 3,
  compress: true,
  interval: '30s',   // check every 30 seconds
  onError: console.error,
});

// later...
watcher.stop();

Options

| Option | Default | Description | |--------|---------|-------------| | maxSize | — | Rotate when file exceeds this ('10MB', '1GB', '500KB') | | maxFiles | 5 | Number of rotated files to keep | | compress | false | Gzip rotated files (app.log.1.gz) | | copytruncate | false | Copy + truncate instead of rename (safer for apps that don't reopen logs) | | interval | 60000 | Poll interval for watchLog() ('30s', '5m', '1h') |

File naming

app.log          → current log
app.log.1        → 1st backup (→ app.log.1.gz if compress)
app.log.2        → 2nd backup
...
app.log.N        → Nth backup (deleted when N > maxFiles)

How it works

1. Stats the log file
2. If size >= maxSize, shifts backups: .N → .N+1, .1 → .2, etc.
3. Renames (or copy/truncates) current log to .1
4. Creates a new empty log file
5. Gzips .1 if compress: true