RCA Mock Site - Load Testing SUT

A production-ready System Under Test (SUT) for load testing and Root Cause Analysis (RCA) validation.

🎯 Purpose

This is a deterministic mock API built with Cloudflare Pages + Functions designed for:

• ✅ Load testing with controlled behaviors
• ✅ RCA agent validation
• ✅ Browser performance metrics testing (LCP, INP, FCP, TTFB)
• ✅ Simulating real-world failure scenarios

🏗️ Architecture

/ (repo root)
│
├── package.json
├── wrangler.toml
├── README.md
├── DEPLOYMENT.md
│
├── /public
│   ├── index.html          # Main page with API call
│   ├── large.html          # LCP testing page
│   └── /assets
│       └── large-image.jpg # 1200x800 test image
│
└── /functions
    └── /api
        └── [[route]].js    # Catch-all API handler

🚀 Features

Controlled API Behaviors

The API supports query parameters for deterministic testing:

Parameter	Type	Purpose	Example
delay	ms	Artificial latency	?delay=3000
status	HTTP code	Simulate HTTP errors	?status=500
size	integer	Payload size (KB)	?size=500
errorType	string	Semantic error type	?errorType=db

Error Types

• db - Database connection timeout
• auth - Unauthorized access

📊 API Examples

Success Response

curl https://your-site.pages.dev/api/test

Simulating Latency

curl https://your-site.pages.dev/api/test?delay=3000

Simulating 500 Error

curl https://your-site.pages.dev/api/test?status=500

Simulating Database Error

curl https://your-site.pages.dev/api/test?status=500&errorType=db

Large Payload

curl https://your-site.pages.dev/api/test?size=500

Combined Scenario

curl https://your-site.pages.dev/api/test?delay=2000&status=503&errorType=db&size=100

🧪 Test Scenarios

DB Bottleneck

/api/test?delay=2000

Infrastructure Crash

/api/test?status=500

Authentication Failure

/api/test?status=401&errorType=auth

Large Payload Latency

/api/test?size=1000

Mixed Load Pattern

Generate traffic with:

• 70% success (200)
• 20% latency (delay=1000-3000ms)
• 10% errors (500)

📈 Browser Performance Testing

Main Page (/)

• Measures LCP with single large image
• API call button for interaction testing
• Lightweight for baseline metrics

Large Page (/large.html)

• Multiple large images for LCP regression
• Slow and fast API buttons
• Real-time duration display

🔧 Local Development

Prerequisites

npm install -g wrangler

Local Testing

wrangler pages dev public --compatibility-date=2024-01-01

Access at: http://localhost:8788

🌐 Deployment

See DEPLOYMENT.md for complete deployment instructions.

Quick deploy to Cloudflare Pages:

1. Push to GitHub
2. Connect repo in Cloudflare Dashboard
3. Set build output: public
4. Deploy

🎯 RCA Signal Mapping

Behavior	Expected RCA
delay ↑	Backend latency
status=500 spike	Infrastructure failure
status=401 spike	Functional auth issue
Large payload + LCP ↑	Frontend regression

✅ Validation Checklist

Before load testing:

• Public URL accessible
• 200 response works
• 500 response works
• delay parameter works
• size parameter works
• Browser page loads correctly
• No caching (check headers)
• Images load properly

🚫 What This Is NOT

• ❌ Not a real backend
• ❌ No database required
• ❌ No authentication system
• ❌ No external dependencies
• ❌ No random behavior (deterministic only)

📝 Technical Constraints

• Cloudflare Pages + Functions only
• No Node.js server
• No external APIs
• No database
• Free tier compatible
• Public URL

🔮 Future Enhancements (Phase 2)

Potential additions:

• Random failure rate parameter
• CPU-intensive operations
• Memory load simulation
• Edge region routing

📄 License

Private project for load testing purposes.

🤝 Contributing

This is a controlled testing environment. Changes should maintain deterministic behavior.

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Note: This SUT is designed for reliability and reproducibility in load testing scenarios.