🪓 Lumberjack

A fast, lightweight Electron-based log viewer with powerful filtering capabilities.

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📸 Screenshots

Main View

Filter in Action

MDC/Diagnostic Context Filter

Elasticsearch Integration

Settings

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✨ Features

• Powerful Filters: AND (&), OR (|), NOT (!) operators
• Filter Profiles: Save, search, import/export and undo filter sets
• Fast Startup: < 2 seconds cold start
• Efficient Rendering: 100,000+ log entries at 60 FPS
• TCP Log Reception: Real-time log streaming
• HTTP Tailing: Incremental Range-based polling of remote log endpoints
• File Watcher Tail: Live-tailing of local log files (with rotation handling)
• Elasticsearch Integration: Query and view logs from Elasticsearch
• MDC/Diagnostic Context: Filter by diagnostic context fields
• Bookmarks: Mark and quickly jump to important log entries
• Alert Rules: Define rules and get notified when logs match
• Auto-Updater: Automatic updates on installed builds (portable mode auto-detected)
• Internationalization: German and English UI (de / en)
• Accessibility: Aria-live announcements, reduced-motion support, keyboard-friendly dialogs
• Cross-Platform: Windows, macOS, Linux

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📡 TCP Log-Streaming Configuration

Lumberjack can receive logs in real-time via TCP. Configure your application to send logs to Lumberjack:

Logback (logback.xml)

Lumberjack expects JSON-formatted logs via TCP. Use the LogstashTcpSocketAppender with LogstashEncoder:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <!-- Console appender for local output -->
    <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
        </encoder>
    </appender>

    <!-- TCP Socket appender for Lumberjack (JSON format) -->
    <appender name="LUMBERJACK" class="net.logstash.logback.appender.LogstashTcpSocketAppender">
        <destination>localhost:4445</destination>
        <encoder class="net.logstash.logback.encoder.LogstashEncoder">
            <includeContext>false</includeContext>
        </encoder>
    </appender>

    <!-- Async wrapper for better performance (optional) -->
    <appender name="ASYNC_LUMBERJACK" class="ch.qos.logback.classic.AsyncAppender">
        <queueSize>500</queueSize>
        <discardingThreshold>0</discardingThreshold>
        <appender-ref ref="LUMBERJACK"/>
    </appender>

    <root level="INFO">
        <appender-ref ref="CONSOLE"/>
        <appender-ref ref="ASYNC_LUMBERJACK"/>
    </root>
</configuration>

Note: You need the logstash-logback-encoder dependency in your project:

<dependency>
    <groupId>net.logstash.logback</groupId>
    <artifactId>logstash-logback-encoder</artifactId>
    <version>9.0</version>
</dependency>

Log4j2 (log4j2.xml)

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
    <Appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
        </Console>

        <!-- TCP Socket for Lumberjack -->
        <Socket name="Lumberjack" host="localhost" port="4445" protocol="TCP">
            <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
        </Socket>
    </Appenders>

    <Loggers>
        <Root level="info">
            <AppenderRef ref="Console"/>
            <AppenderRef ref="Lumberjack"/>
        </Root>
    </Loggers>
</Configuration>

Log4j 1.x (log4j.properties)

# Console appender
log4j.appender.console=org.apache.log4j.ConsoleAppender
log4j.appender.console.layout=org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss.SSS} [%t] %-5p %c{1} - %m%n

# TCP Socket for Lumberjack
log4j.appender.lumberjack=org.apache.log4j.net.SocketAppender
log4j.appender.lumberjack.remoteHost=localhost
log4j.appender.lumberjack.port=4445
log4j.appender.lumberjack.reconnectionDelay=10000

# Root Logger
log4j.rootLogger=INFO, console, lumberjack

💡 Tip: Configure the TCP port in Lumberjack under Settings → TCP Port (default: 4445)

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🌐 HTTP Tailing

Lumberjack can incrementally tail remote log endpoints (e.g. Spring Boot Actuator's /actuator/logfile) using HTTP Range requests. Only new bytes since the last poll are transferred — efficient even for large rolling log files.

Configure in Lumberjack: File → Tail HTTP URL…

• URL: e.g. http://localhost:8080/actuator/logfile
• Interval: poll interval in ms (default: 2000)
• Headers: optional auth headers (e.g. Authorization: Bearer …)
• Allow insecure SSL: skip certificate validation (self-signed dev servers)

Rotation (file shrinks / Content-Range jumps backward) is detected automatically and the offset is reset.

Example: Spring Boot

# application.properties
logging.file.name=logs/app.log
management.endpoints.web.exposure.include=logfile
management.endpoint.logfile.external-file=logs/app.log

Then point Lumberjack at http://localhost:8080/actuator/logfile.

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📁 File Tailing

Lumberjack can live-tail local log files (fs.watchFile-based polling, robust across editors and rotation strategies).

Configure in Lumberjack: File → Tail File…

• Auto-detects file rotation (truncate / rename) and re-attaches.
• Works with JSON-per-line and plain-text patterns.
• Combine with filter profiles for focused live monitoring.

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🔔 Alert Rules

Define rules that match incoming log entries (by level, message, MDC fields…) and receive native OS notifications when they fire. Manage rules under Settings → Alerts.

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🔖 Bookmarks

Mark important entries with one click (or Ctrl/Cmd+D) and jump between them via the bookmarks popover in the toolbar. Bookmarks survive filter changes.

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🌍 Internationalization

Lumberjack ships with German (de) and English (en) translations. Switch the UI language under Settings → Language. Both Electron menus and renderer UI are localized.

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Filter Examples

error|warn           → Messages containing "error" OR "warn"
service&timeout      → Messages containing "service" AND "timeout"
QcStatus&!CB23       → "QcStatus", but NOT "CB23"

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🚀 Quick Start

Prerequisites

• Node.js 22.12+ (LTS)
• npm

Installation

macOS (Homebrew)

brew tap moxbo/tap
brew install --cask lumberjack

macOS / Windows / Linux (Manual)

Download the latest release from GitHub Releases:

• macOS: Lumberjack-x.x.x-arm64.dmg or Lumberjack-x.x.x-x64.dmg
• Windows: Lumberjack-x.x.x-portable.exe or Lumberjack-Setup-x.x.x.exe
• Linux: Lumberjack-x.x.x.AppImage

Development

# Install dependencies
npm install

# Start development mode
npm run dev

# Run tests
npm test

Build

# Windows Portable
npm run build:portable:x64

# Windows Installer (NSIS)
npm run build:x64

# macOS DMG
npm run build:mac:dmg

Build artifacts are located in release/build/.

Installation

⚠️ Note: On first launch, you may see a security warning because the app is not signed with an Apple Developer certificate.

macOS (if you see "damaged or incomplete" message):

# Open Terminal and run:
xattr -cr /Applications/Lumberjack.app
# Or for DMG files in the Downloads folder:
xattr -cr ~/Downloads/Lumberjack*.dmg

Alternatively: Right-click → "Open" → Confirm "Open"

Windows: Click "More info" → "Run anyway"

See Troubleshooting for more details.

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📦 Project Structure

lumberjack/
├── src/
│   ├── main/         # Electron Main Process
│   └── renderer/     # React/Preact UI
├── assets/           # Icons (ico, icns)
├── docs/             # Documentation
├── scripts/          # Build & Test Scripts
└── release/          # Build Output

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📖 Documentation

Full documentation is available in the docs/ folder:

Topic	Document
Overview	docs/INDEX.md
Deployment	docs/DEPLOYMENT_GUIDE.md
Troubleshooting	docs/user/TROUBLESHOOTING_AND_FAQ.md
Performance	docs/developer/PERFORMANCE.md
Architecture	docs/developer/ARCHITECTURE_DECISION.md

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⚡ Performance

• Cold Start: < 2 seconds
• Warm Start: < 0.3 seconds
• Bundle Size: 38 KB (12 KB gzipped)
• Virtual Scrolling: 100,000+ entries @ 60 FPS

Production-Ready Features

• ✅ Adaptive Batch Processing
• ✅ Non-blocking File I/O
• ✅ Circuit Breaker Pattern
• ✅ Health Monitoring
• ✅ Rate Limiting

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🔧 Troubleshooting

Finding Logs

OS	Path
Windows	%APPDATA%\Lumberjack\logs\main.log
macOS	~/Library/Logs/Lumberjack/main.log
Linux	~/.config/Lumberjack/logs/main.log

Common Issues

Problem	Solution
Icon not visible	Run npm run icon:generate, then rebuild
App hangs	Check logs, run npm run diagnose:memory
Slow startup	See Performance docs

More information: Troubleshooting Guide

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🛠️ Development

Available Scripts

npm run dev          # Development mode
npm run build        # Production build
npm test             # Run tests
npm run lint         # Check code
npm run lint:fix     # Auto-fix code issues
npm run format       # Format code
npm run icon:generate # Regenerate icons
npm run diagnose:memory # Memory diagnostics

Release Workflow

The version is automatically determined from Git tags:

# 1. Create tag (version without "v" is used in the app)
git tag v1.0.5

# 2. Push
git push && git push --tags

# 3. Build (version is automatically taken from tag)
npm run build:portable:x64  # Windows
npm run build:mac:dmg       # macOS

Version Logic:

• Exact tag on HEAD: v1.0.5 → Version 1.0.5
• Commits after tag: v1.0.5 + 3 commits → Version 1.0.5-dev.3
• Environment variable: RELEASE_VERSION=1.2.0 overrides all

Architecture

• Main Process: Electron, TCP Server, File I/O
• Renderer Process: Preact, Virtual Scrolling
• IPC: Structured communication via contextBridge

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📄 License

MIT © Moritz Bohm

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🤝 Contributing

Contributions are welcome! See CONTRIBUTING.md for details.

Quick guide:

1. Fork the repository
2. Create feature branch: git checkout -b feature/amazing-feature
3. Commit: git commit -m 'Add amazing feature'
4. Push: git push origin feature/amazing-feature
5. Open a Pull Request

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🔒 Security

Found a security vulnerability? See SECURITY.md.