Advanced Features

# Script options

export const options = {
  workers: 10,
  duration: '1m',
  jitter: '500ms',   // Add 0-500ms random latency
  drop: 0.05,        // Drop 5% of requests
};

# CLI flags

$ fusillade run test.js --jitter 500ms --drop 0.05

# Export HAR from browser

1. Open Chrome DevTools (F12)
2. Go to Network tab
3. Perform the user flow you want to test
4. Right-click → "Save all as HAR with content"

# Convert to script

$ fusillade convert --input recording.har --output test.js

# Preview without writing
$ fusillade convert --input recording.har --dry-run

# Generated script

// Auto-generated from recording.har
export const options = {
  workers: 1,
  iterations: 1,
};

export default function() {
  // GET https://example.com/
  http.get('https://example.com/', {
    headers: {
      'Accept': 'text/html',
      'User-Agent': 'Mozilla/5.0...',
    }
  });

  // POST https://example.com/api/login
  http.post('https://example.com/api/login', JSON.stringify({
    "username": "user",
    "password": "***"
  }), {
    headers: {
      'Content-Type': 'application/json',
    }
  });

  sleep(0.5);
}

# Start recording proxy on port 8085
$ fusillade record -o recorded-test.js -p 8085

# Configure your app/browser to use http://localhost:8085 as proxy
# Perform actions you want to test
# Press Ctrl+C to stop and generate script

# Capture errors

# Save failed requests to file
$ fusillade run test.js --capture-errors errors.json

# errors.json contains full request details for debugging

# Replay failed requests

# Replay one by one
$ fusillade replay errors.json

# Replay in parallel
$ fusillade replay errors.json --parallel

# Export as cURL commands
$ fusillade export errors.json --format curl > debug_commands.sh

# Export baseline
$ fusillade run test.js --export-json baseline.json

# ... make changes ...

# Export current
$ fusillade run test.js --export-json current.json

# Compare
$ fusillade compare baseline.json current.json

# Output:
# Metric              Baseline    Current     Change
# http_req_duration   145ms       167ms       +15.2% ⚠️
# http_req_failed     0.5%        0.8%        +60.0% ⚠️
# http_reqs           15,234      14,891      -2.3%

# Enable history saving
$ fusillade run test.js --save-history

# View history
$ fusillade history
# ID   Date                  Script      Workers  Duration  P95
# 1    2024-01-15 10:30:00  test.js     10    30s       145ms
# 2    2024-01-15 11:00:00  test.js     50    1m        178ms
# 3    2024-01-15 14:22:00  stress.js   100   5m        234ms

# View specific run
$ fusillade history --show 3

# Limit results
$ fusillade history --limit 10

export const options = {
  workers: 100000,
  duration: '10m',

  // Discard response bodies (only keep status/headers)
  response_sink: true,

  // Disable per-endpoint metrics (reduces cardinality)
  no_endpoint_tracking: true,

  // Auto-throttle spawning when memory is high
  memory_safe: true,

  // Smaller stack per worker (default 32KB)
  stack_size: 16384,
};

# CLI equivalent

$ fusillade run test.js -w 100000 \
  --response-sink \
  --no-endpoint-tracking \
  --memory-safe

# Watch for changes and re-run
$ fusillade run test.js --watch

# Great for development - edit script, see results immediately

# Check script syntax and configuration
$ fusillade validate test.js

# Validate with config file
$ fusillade validate test.js -c config.yaml

# Output:
# ✓ Script syntax valid
# ✓ Options parsed successfully
# ✓ Thresholds valid
# ✓ 3 scenarios defined

# Estimate data transfer costs
$ fusillade run test.js --estimate-cost

# Set cost limit (abort if exceeded)
$ fusillade run test.js --estimate-cost 100  # $100 limit

# Output:
# Estimated data transfer: 15.2 GB
# Estimated cost (AWS): $1.37
# Estimated cost (GCP): $1.22

console.debug('Detailed debugging info');  // Only shown with --log-level debug
console.log('Normal info message');
console.warn('Warning: rate limit approaching');
console.error('Error: request failed');

// Pretty-print tabular data
console.table([
  { name: 'Alice', score: 95 },
  { name: 'Bob', score: 87 },
]);

describe("Cart Logic", () => {
  test("calculates total correctly", () => {
    const total = calculateTotal(100, 2);
    expect(total).toBe(200);
  });

  test("applies discount", () => {
    const discounted = applyDiscount(100, 0.1);
    expect(discounted).toBe(90);
  });
});

segment('Login Flow', () => {
  http.post('/login', credentials);

  segment('Dashboard', () => {
    http.get('/dashboard');  // Metric: "Login Flow::Dashboard::/dashboard"
  });
});

// Nested segments create hierarchical names

export default function() {
  http.get('https://api.example.com/data', { name: 'getData' });

  // Query stats for a named request
  const s = stats.get('getData');
  print(`p95: ${s.p95}ms, avg: ${s.avg}ms, count: ${s.count}`);

  // Adaptive behavior based on performance
  if (s.p95 > 500) {
    print('Warning: p95 latency exceeds 500ms');
  }
}

export default function() {
  // Use worker ID to partition test data
  const userId = users[__WORKER_ID % users.length];

  // Access environment variables
  const apiKey = __ENV.API_KEY || 'default-key';

  // Track per-worker state across iterations
  __WORKER_STATE.loginCount = (__WORKER_STATE.loginCount || 0) + 1;
  console.log(`Worker ${__WORKER_ID} iteration ${__ITERATION}, logins: ${__WORKER_STATE.loginCount}`);

  // Store session data that persists
  if (!__WORKER_STATE.token) {
    const res = http.post('/login', credentials);
    __WORKER_STATE.token = res.json().token;
  }
  // Use cached token in subsequent iterations
  http.get('/api/data', { headers: { 'Authorization': `Bearer ${__WORKER_STATE.token}` } });
}

# .env file format
API_KEY=your-secret-key
BASE_URL=https://api.example.com
DEBUG=true

# Generate completions for your shell
$ fusillade completion bash >> ~/.bashrc
$ fusillade completion zsh >> ~/.zshrc
$ fusillade completion fish > ~/.config/fish/completions/fusillade.fish

# PowerShell
$ fusillade completion powershell >> $PROFILE

# Generate JSON schema for config validation
$ fusillade schema -o fusillade.schema.json