Lobster

Lobster is an intelligent web stress testing tool that automatically discovers URLs by crawling your application and validates performance under load. Point it at your app, and it handles the rest.

Why Lobster?

• Zero Config: Point and shoot
• Auto-Discovery: Crawls and finds all URLs
• Pass/Fail Validation: Not just metrics
• Security Hardened: SSRF protection, secure credential handling
• CI/CD Ready: Fast, reliable, scriptable

Features

• Auto URL Discovery: Crawls and discovers all linked pages
• Concurrent Testing: Configurable workers with rate limiting
• Performance Validation: Pass/fail against targets (p95, p99, success rate)
• Rich Reports: HTML (charts), JSON (API), console (real-time)
• Smart Rate Limiting: Token bucket via goflow
• robots.txt Compliance: Respects website preferences by default
• SSRF Protection: Blocks private IP ranges by default

Quick Start

Installation

go install github.com/1mb-dev/lobster/cmd/lobster@latest

Or clone and build:

git clone https://github.com/1mb-dev/lobster.git
cd lobster
go build -o lobster cmd/lobster/main.go

Basic Usage

Test a public website:

lobster -url https://example.com -duration 30s

Test your local application:

lobster -url http://localhost:3000 -allow-private-ips

Lobster crawls your app, tests all discovered URLs under load, and generates reports.

With Authentication

# Basic authentication
export LOBSTER_AUTH_PASSWORD="secret"
lobster -url https://api.example.com -auth-type basic -auth-username admin

# Bearer token
export LOBSTER_AUTH_TOKEN="your-api-token"
lobster -url https://api.example.com -auth-type bearer

For more examples, see the Quick Start Guide.

Configuration

Key flags: -url, -concurrency, -duration, -rate, -max-depth, -output

Use -config config.json for complex setups. See examples/config.example.json for template.

Full reference: Configuration Guide

How It Works

1. URL Discovery Phase

• Starts with the base URL
• Parses HTML responses for <a href> links
• Resolves relative URLs to absolute
• Filters to same-domain links only
• Maintains a queue of discovered URLs
• Respects max depth configuration

2. Concurrent Testing Phase

• Spawns configurable number of worker goroutines
• Distributes URLs across workers
• Applies rate limiting via token bucket
• Tracks response times and status codes
• Continues until duration expires

3. Analysis Phase

• Calculates aggregate metrics
• Computes percentiles (p95, p99)
• Validates against performance targets
• Identifies slow requests and errors

4. Reporting Phase

• Generates JSON output with detailed metrics
• Creates HTML report with interactive charts
• Provides console summary with pass/fail indicators
• Outputs actionable recommendations

Architecture

Lobster follows Clean Architecture principles:

lobster/
├── cmd/lobster/       # CLI entry point
├── internal/
│   ├── cli/            # CLI utilities
│   ├── config/         # Configuration loading
│   ├── crawler/        # URL discovery
│   ├── domain/         # Core entities
│   ├── reporter/       # Report generation
│   ├── robots/         # robots.txt parsing
│   ├── tester/         # Load testing engine
│   ├── util/           # Shared utilities
│   └── validator/      # Performance validation
├── docs/               # Documentation
└── examples/           # Example configs

Domain -> Crawler -> Tester -> Reporter + Validator

See Architecture for technical details.

Reports

Console Output

Real-time progress updates and detailed summary:

=== STRESS TEST RESULTS ===
Duration: 2m0s
URLs Discovered: 42
Total Requests: 2,450
Successful Requests: 2,442
Failed Requests: 8
Average Response Time: 18.7ms
Requests/Second: 20.4
Success Rate: 99.67%

PERFORMANCE TARGET VALIDATION
============================================================
PASS Requests per Second:         20.4 req/s
PASS Average Response Time:        18.7ms
PASS 95th Percentile Response Time: 35.2ms
PASS Success Rate:                 99.67%

Overall: 4/4 targets met (100.0%)
ALL PERFORMANCE TARGETS MET!

HTML Report

Interactive report with:

• Overview dashboard with key metrics
• Response status distribution (pie charts)
• URL validation table (sortable)
• Response time histogram
• Error analysis
• Slow request identification

JSON Report

Machine-readable format for integration:

{
  "duration": "2m0s",
  "urls_discovered": 42,
  "total_requests": 2450,
  "successful_requests": 2442,
  "failed_requests": 8,
  "average_response_time": "18.7ms",
  "requests_per_second": 20.4,
  "success_rate": 99.67,
  "performance_validation": {
    "targets_met": 4,
    "total_targets": 4,
    "overall_status": "PRODUCTION_READY"
  }
}

Use Cases

• Development testing and regression detection
• Pre-deployment validation
• CI/CD performance gates
• Capacity planning

Documentation

• Quick Start
• Configuration Reference
• Architecture
• Development Guide
• Changelog

Contributing

Contributions are welcome. See Contributing Guidelines.

Development

git clone https://github.com/1mb-dev/lobster.git
cd lobster
make help      # See all targets
make test      # Run tests
make build     # Build binary

Responsible Use

Only test systems you own or have written permission to test.

Unauthorized testing may violate computer fraud laws. Respect robots.txt (enabled by default), use rate limits, handle reports securely.

See Responsible Use for full guidelines.

License

MIT License - see LICENSE for details.

Support

• Documentation
• Issues
• Discussions

Built with goflow