Fusillade Documentation

High-performance load testing engine built in Rust

Fusillade is a modern load testing platform that combines the raw performance of Rust with the developer-friendly scripting of JavaScript. Write tests in familiar JS syntax, run them with predictable performance characteristics.

Why Fusillade?

  • Rust performance with JavaScript scripting
  • Accurate metrics (network time only, no JS overhead)
  • Multi-protocol: HTTP/2, WebSocket, gRPC, MQTT, AMQP, SSE
  • Browser automation for real user experience testing
  • Built-in thresholds for CI/CD pass/fail

Tech Stack

RuntimeRust + QuickJS
ConcurrencyOS Threads
HTTPhyper (HTTP/1.1 & HTTP/2)
HistogramsHDR histograms

No imports needed

All APIs are available as globals. Use local imports only for your own modules.

HTTP & Protocols

http, ws, sse, GrpcClient, JsMqttClient, JsAmqpClient

Testing

check, sleep, print, describe, test, expect

Data

SharedArray, SharedCSV, open, __ENV, __WORKER_ID

Utilities

utils, crypto, encoding, metrics, stats, chromium

Documentation

Getting Started

Installation, first test, shell completion

Configuration

Options, executors, scenarios, thresholds

HTTP API

Requests, responses, cookies, retries

Protocols

WebSocket, gRPC, MQTT, AMQP, SSE

Browser Testing

Chromium automation, real user metrics

Metrics

Built-in metrics, thresholds, exports

Data Loading

CSV, JSON, environment variables

CLI Reference

Commands, flags, TUI, interactive mode

Distributed

Cloud, multi-region, Kubernetes, CI/CD

Advanced

Chaos testing, HAR conversion, memory

Quick Example

# test.js

export const options = {
  workers: 10,
  duration: '30s',
  thresholds: {
    'http_req_duration': ['p95 < 500'],
    'http_req_failed': ['rate < 0.01'],
  }
};

export default function() {
  const res = http.get('https://api.example.com/users');

  check(res, {
    'status is 200': (r) => r.status === 200,
    'response time < 500ms': (r) => r.timings.duration < 500,
  });

  sleep(1);
}

# Run

$ fusillade run test.js

Common Patterns

API with Authentication

const users = new SharedCSV('./data/users.csv');

export function setup() {
  // Login once, share token with all workers
  const res = http.post('https://api.example.com/login', JSON.stringify({
    email: 'admin@example.com',
    password: __ENV.ADMIN_PASSWORD
  }));
  return { token: res.json().token };
}

export default function(data) {
  http.get('https://api.example.com/protected', {
    headers: { Authorization: 'Bearer ' + data.token }
  });
}

Ramping Load Test

export const options = {
  stages: [
    { duration: '1m', target: 10 },   // Ramp up
    { duration: '3m', target: 10 },   // Steady
    { duration: '1m', target: 50 },   // Spike
    { duration: '1m', target: 0 },    // Ramp down
  ],
  thresholds: {
    'http_req_duration': ['p95 < 500'],
  }
};

Multiple User Flows

export const options = {
  scenarios: {
    browse: {
      workers: 50,
      duration: '5m',
      exec: 'browseProducts',
    },
    checkout: {
      workers: 10,
      duration: '5m',
      exec: 'checkoutFlow',
    },
  },
};

export function browseProducts() {
  http.get('https://shop.example.com/products');
  sleep(2);
}

export function checkoutFlow() {
  http.post('https://shop.example.com/cart/add', JSON.stringify({ item: 1 }));
  http.post('https://shop.example.com/checkout');
  sleep(5);
}

CI/CD Integration

$ fusillade run test.js \
    --headless \
    --abort-on-fail \
    --threshold "http_req_duration:p95<500" \
    --export-json results.json \
    --out junit=results.xml

API Quick Reference

CategoryFunctions
HTTPhttp.get() .post() .put() .del() .batch() .cookieJar()
WebSocketws.connect() socket.send() .recv() .close()
Testingcheck(res, {...}) sleep(secs) print(msg)
Datanew SharedArray() new SharedCSV() open(path) __ENV.VAR
Utilsutils.uuid() .randomString() .randomInt() .randomEmail()
Cryptocrypto.md5() .sha256() .hmac()
Metricsmetrics.histogramAdd() .counterAdd() .gaugeSet() .rateAdd()
Browserchromium.launch() page.goto() .click() .metrics()