API Chaos Monkey 🐒💥

Unleash controlled chaos on your Node.js APIs for stress testing and resilience building!

🎯 Problem Statement

Testing APIs under stress is like eating plain oatmeal—boring, predictable, and nobody's idea of a good time. You send a few requests, get some 200 OKs, and call it a day. But real-world chaos? Unpredictable delays, random failures, garbled data—that's the jungle your API needs to survive! Without a wild shake-up, how do you know your app can handle the madness of production? 🐒💥

🚀 Solution

Say hello to API Chaos Monkey, a mischievous middleware that turns your Node.js APIs into a playground of pandemonium! Inspired by Netflix's Chaos Monkey, this package randomly delays, drops, or garbles your API responses to simulate the wildest real-world scenarios. It's stress-testing with a side of anarchy—because who said reliability can't be a riot? 🌩️

🎪 What It Helps With

• Stress Testing: See how your API holds up when the monkey throws wrenches (or bananas) at it
• Resilience Training: Prepare your app for network hiccups, server meltdowns, and data disasters
• Team Entertainment: Watch your colleagues panic as their perfect code faces the chaos monkey—priceless!
• Real-World Prep: Simulate the unpredictable nature of production environments in a fun way

🛠️ Technologies Supported

• Node.js: Core runtime (v12+ recommended)
• Express: Full middleware support
• Koa: Native Koa middleware
• Fastify: Plugin architecture support
• Raw HTTP: Works with any HTTP server
• Universal: Runs anywhere Node.js does

⚡ Features

• 🕐 Random Delays: Responses lag anywhere from 1ms to 10s—because timing is everything!
• 💣 Error Bombs: Drops 500 Internal Server Errors or other HTTP disasters at random
• 🎭 Gibberish Generator: Returns mangled JSON to test parsing resilience
• 🎚️ Chaos Levels: Tune the madness—mild for a light shake, ape-pocalypse for total mayhem
• ⚙️ Highly Configurable: Control delay ranges, error rates, and chaos intensity
• 📊 Statistics Tracking: Monitor chaos impact with detailed metrics
• ⏰ Time Windows: Schedule chaos for specific hours
• 🎯 Route Filtering: Target specific endpoints or exclude critical paths
• 🔧 Custom Chaos: Write your own chaos functions for advanced scenarios

📦 Installation

npm install api-chaos-monkey

🎮 Quick Start

Express - Basic Chaos

const express = require('express');
const apiChaosMonkey = require('api-chaos-monkey');

const app = express();

// Unleash mild chaos
app.use(apiChaosMonkey({ chaos: 'mild' }));

app.get('/', (req, res) => {
  res.json({ message: 'Survive this!' });
});

app.listen(3000, () => {
  console.log('🐒 Server running with chaos enabled!');
});

Express - Advanced Configuration

const express = require('express');
const apiChaosMonkey = require('api-chaos-monkey');

const app = express();

app.use(apiChaosMonkey({
  chaos: 'wild',
  probability: 0.3,                    // 30% chance of chaos
  delayRange: [1000, 5000],           // 1-5 second delays
  errorCodes: [500, 503, 502, 429],   // Various error types
  enabledRoutes: ['/api/'],           // Only chaos on API routes
  disabledRoutes: ['/health'],        // Never chaos health checks
  timeWindows: [                      // Only during work hours
    { start: '09:00', end: '17:00' }
  ],
  chaosWeights: {                     // Control chaos distribution
    delayWeight: 40,
    errorWeight: 40,
    gibberishWeight: 20
  },
  logging: true                       // Enable chaos logging
}));

app.get('/health', (req, res) => res.json({ status: 'ok' }));
app.get('/api/users', (req, res) => res.json({ users: [] }));

app.listen(3000);

Koa Support

const Koa = require('koa');
const apiChaosMonkey = require('api-chaos-monkey');

const app = new Koa();

app.use(apiChaosMonkey.koa({ chaos: 'wild' }));

app.use(ctx => {
  ctx.body = { message: 'Koa chaos enabled!' };
});

app.listen(3000);

Fastify Support

const fastify = require('fastify');
const apiChaosMonkey = require('api-chaos-monkey');

const app = fastify();

app.register(apiChaosMonkey.fastify({ chaos: 'ape-pocalypse' }));

app.get('/', async (request, reply) => {
  return { message: 'Fastify chaos mode!' };
});

app.listen(3000);

🎪 Chaos Levels

Built-in Levels

Level	Probability	Delay Range	Error Codes	Description
mild	10%	100-1000ms	[500]	Gentle chaos for development
wild	30%	500-3000ms	[500,503,502]	Moderate chaos for testing
ape-pocalypse	70%	1-10 seconds	[500,503,502,429,404]	Extreme chaos for stress testing
custom	20%	200-2000ms	[500,503]	Base for custom configurations

Custom Configuration

const chaosConfig = {
  probability: 0.4,
  delayRange: [500, 8000],
  errorCodes: [500, 503, 502, 429, 404],
  chaosWeights: {
    delayWeight: 30,    // 30% delays
    errorWeight: 50,    // 50% errors  
    gibberishWeight: 20 // 20% gibberish
  },
  enabledRoutes: ['/api/', '/v1/'],
  disabledRoutes: ['/health', '/metrics'],
  timeWindows: [
    { start: '09:00', end: '12:00' },
    { start: '14:00', end: '17:00' }
  ],
  logging: true
};

app.use(apiChaosMonkey(chaosConfig));

🔧 Advanced Features

Custom Chaos Functions

const { createCustomChaos } = require('api-chaos-monkey');

const memoryLeakChaos = createCustomChaos(async (context) => {
  const leak = new Array(100000).fill('CHAOS');
  return {
    type: 'memory-leak',
    message: 'Memory leak induced! 🐒🧠'
  };
});

app.use(apiChaosMonkey({
  customChaos: [memoryLeakChaos]
}));

Statistics Monitoring

const chaosMonkey = apiChaosMonkey({ chaos: 'wild' });
const engine = chaosMonkey.chaosEngine;

// Get statistics
setInterval(() => {
  const stats = engine.getStats();
  console.log(`Chaos Stats:`, stats);
}, 10000);

// Listen to chaos events
engine.on('chaos:delay', (data) => {
  console.log(`🐒⏰ Delayed request ${data.chaosId} by ${data.delay}ms`);
});

engine.on('chaos:error', (data) => {
  console.log(`🐒💥 Error ${data.statusCode} for request ${data.chaosId}`);
});

📊 Example Outputs

Delayed Response

{
  "message": "Hello World",
  "timestamp": "2025-01-07T10:30:45.123Z"
}
// ↑ Delivered after 3.2 seconds

Error Response

{
  "error": true,
  "message": "Internal Server Error - The monkey broke something! 🐒💥",
  "chaosId": "abc123def",
  "timestamp": "2025-01-07T10:30:45.123Z"
}

Gibberish Response

{
  "chaos": true,
  "message": "OOGA BOOGA",
  "monkeyLevel": 87,
  "bananas": ["CHAOS", "MAYHEM", "HAVOC"],
  "warning": "This response has been monkey-fied! 🐒"
}

🧪 Testing & Examples

Run the included examples:

# Basic Express example
npm run example

# Advanced demo with all features
npm run demo

# Run tests
npm test

🎯 Use Cases

• Development: Add controlled chaos to catch edge cases early
• QA Testing: Stress test applications without complex setups
• Load Testing: Simulate real-world network conditions
• Team Training: Practice incident response and debugging
• Fun: Prank your colleagues (use responsibly! 😈)

🚨 Safety First

• Never use in production without careful consideration
• Start with mild chaos level and increase gradually
• Always exclude critical endpoints like /health
• Use time windows to limit chaos to safe hours
• Monitor your applications closely when chaos is enabled

🤝 Contributing

Got a crazier chaos idea? Join the monkey party!

1. Fork the repository
2. Create your chaos branch: git checkout -b my-chaos-feature
3. Commit your mayhem: git commit -am 'Add some chaos'
4. Push to the branch: git push origin my-chaos-feature
5. Submit a pull request

📄 License

MIT License - Free to unleash, tweak, and chaos-ify!

🙏 Credits

Built with chaos and ❤️ by Ankit

Inspired by Netflix's Chaos Monkey and the principles of chaos engineering.

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Ready to unleash some havoc? Install API Chaos Monkey and let the mayhem begin! 🐒💣

Remember: With great chaos comes great responsibility. Use wisely!# API-Chaos-Monkey