Synthetic Monitoring Overview
Set up synthetic monitoring to automatically simulate real user journeys, API workflows, and critical business transactions to detect issues and validate performance.
When to Use End-to-end workflow validation API flow testing User journey simulation Transaction monitoring Critical path validation Instructions 1. Synthetic Tests with Playwright // synthetic-tests.js const { chromium } = require('playwright');
class SyntheticMonitor { constructor(config = {}) { this.baseUrl = config.baseUrl || 'https://app.example.com'; this.timeout = config.timeout || 30000; }
async testUserFlow() { const browser = await chromium.launch(); const page = await browser.newPage(); const metrics = { steps: {} }; const startTime = Date.now();
try {
// Step 1: Navigate to login
let stepStart = Date.now();
await page.goto(`${this.baseUrl}/login`, { waitUntil: 'networkidle' });
metrics.steps.navigation = Date.now() - stepStart;
// Step 2: Perform login
stepStart = Date.now();
await page.fill('input[name="email"]', 'test@example.com');
await page.fill('input[name="password"]', 'password123');
await page.click('button[type="submit"]');
await page.waitForNavigation({ waitUntil: 'networkidle' });
metrics.steps.login = Date.now() - stepStart;
// Step 3: Navigate to dashboard
stepStart = Date.now();
await page.goto(`${this.baseUrl}/dashboard`, { waitUntil: 'networkidle' });
metrics.steps.dashboard = Date.now() - stepStart;
// Step 4: Search for products
stepStart = Date.now();
await page.fill('input[placeholder="Search products"]', 'laptop');
await page.waitForSelector('.product-list');
metrics.steps.search = Date.now() - stepStart;
// Step 5: Add to cart
stepStart = Date.now();
const firstProduct = await page.$('.product-item');
if (firstProduct) {
await firstProduct.click();
await page.click('button:has-text("Add to Cart")');
await page.waitForSelector('[data-testid="cart-count"]');
}
metrics.steps.addToCart = Date.now() - stepStart;
metrics.totalTime = Date.now() - startTime;
metrics.status = 'success';
} catch (error) {
metrics.status = 'failed';
metrics.error = error.message;
metrics.totalTime = Date.now() - startTime;
} finally {
await browser.close();
}
return metrics;
}
async testMobileUserFlow() { const browser = await chromium.launch(); const context = await browser.createBrowserContext({ ...chromium.devices['iPhone 12'] }); const page = await context.newPage();
try {
const metrics = { device: 'iPhone 12', steps: {} };
const startTime = Date.now();
let stepStart = Date.now();
await page.goto(this.baseUrl, { waitUntil: 'networkidle' });
metrics.steps.navigation = Date.now() - stepStart;
const viewport = page.viewportSize();
metrics.viewport = viewport;
stepStart = Date.now();
await page.click('.menu-toggle');
await page.waitForSelector('.mobile-menu.open');
metrics.steps.mobileInteraction = Date.now() - stepStart;
metrics.totalTime = Date.now() - startTime;
metrics.status = 'success';
return metrics;
} catch (error) {
return { status: 'failed', error: error.message, device: 'iPhone 12' };
} finally {
await browser.close();
}
}
async testWithPerformanceMetrics() { const browser = await chromium.launch(); const page = await browser.newPage();
try {
await page.goto(this.baseUrl, { waitUntil: 'networkidle' });
const perfMetrics = JSON.parse(
await page.evaluate(() => JSON.stringify(window.performance.timing))
);
const metrics = {
navigationTiming: {
domInteractive: perfMetrics.domInteractive - perfMetrics.navigationStart,
domComplete: perfMetrics.domComplete - perfMetrics.navigationStart,
loadComplete: perfMetrics.loadEventEnd - perfMetrics.navigationStart
},
status: 'success'
};
return metrics;
} catch (error) {
return { status: 'failed', error: error.message };
} finally {
await browser.close();
}
}
async recordMetrics(testName, metrics) { try { await axios.post('http://monitoring-service/synthetic-results', { testName, timestamp: new Date(), metrics, passed: metrics.status === 'success' }); } catch (error) { console.error('Failed to record metrics:', error); } } }
module.exports = SyntheticMonitor;
- API Synthetic Tests // api-synthetic-tests.js const axios = require('axios');
class APISyntheticTests { constructor(config = {}) { this.baseUrl = config.baseUrl || 'https://api.example.com'; this.client = axios.create({ baseURL: this.baseUrl }); }
async testAuthenticationFlow() { const results = { steps: {}, status: 'success' };
try {
const registerStart = Date.now();
const registerRes = await this.client.post('/auth/register', {
email: `test-${Date.now()}@example.com`,
password: 'Test@123456'
});
results.steps.register = Date.now() - registerStart;
if (registerRes.status !== 201) throw new Error('Registration failed');
const loginStart = Date.now();
const loginRes = await this.client.post('/auth/login', {
email: registerRes.data.email,
password: 'Test@123456'
});
results.steps.login = Date.now() - loginStart;
const token = loginRes.data.token;
const authStart = Date.now();
await this.client.get('/api/profile', {
headers: { Authorization: `Bearer ${token}` }
});
results.steps.authenticatedRequest = Date.now() - authStart;
const logoutStart = Date.now();
await this.client.post('/auth/logout', {}, {
headers: { Authorization: `Bearer ${token}` }
});
results.steps.logout = Date.now() - logoutStart;
return results;
} catch (error) {
results.status = 'failed';
results.error = error.message;
return results;
}
}
async testTransactionFlow() { const results = { steps: {}, status: 'success' };
try {
const orderStart = Date.now();
const orderRes = await this.client.post('/api/orders', {
items: [{ sku: 'ITEM-001', quantity: 2 }]
}, {
headers: { 'X-Idempotency-Key': `order-${Date.now()}` }
});
results.steps.createOrder = Date.now() - orderStart;
const getStart = Date.now();
const getRes = await this.client.get(`/api/orders/${orderRes.data.id}`);
results.steps.getOrder = Date.now() - getStart;
const paymentStart = Date.now();
await this.client.post(`/api/orders/${orderRes.data.id}/payment`, {
method: 'credit_card',
amount: getRes.data.total
});
results.steps.processPayment = Date.now() - paymentStart;
return results;
} catch (error) {
results.status = 'failed';
results.error = error.message;
return results;
}
}
async testUnderLoad(concurrentUsers = 10, duration = 60000) { const startTime = Date.now(); const results = { totalRequests: 0, successfulRequests: 0, failedRequests: 0, averageResponseTime: 0, p95ResponseTime: 0 };
const responseTimes = [];
const makeRequest = async () => {
const reqStart = Date.now();
try {
await this.client.get('/api/health');
results.successfulRequests++;
responseTimes.push(Date.now() - reqStart);
} catch {
results.failedRequests++;
}
results.totalRequests++;
};
const userSimulations = Array(concurrentUsers).fill(null).map(async () => {
while (Date.now() - startTime < duration) {
await makeRequest();
await new Promise(r => setTimeout(r, Math.random() * 1000));
}
});
await Promise.all(userSimulations);
responseTimes.sort((a, b) => a - b);
results.averageResponseTime =
responseTimes.reduce((a, b) => a + b, 0) / responseTimes.length;
results.p95ResponseTime =
responseTimes[Math.floor(responseTimes.length * 0.95)];
return results;
} }
module.exports = APISyntheticTests;
- Scheduled Synthetic Monitoring // scheduled-monitor.js const cron = require('node-cron'); const SyntheticMonitor = require('./synthetic-tests'); const APISyntheticTests = require('./api-synthetic-tests'); const axios = require('axios');
class ScheduledSyntheticMonitor { constructor(config = {}) { this.eMonitor = new SyntheticMonitor(config); this.apiTests = new APISyntheticTests(config); this.alertThreshold = config.alertThreshold || 5000; }
start() { cron.schedule('/5 * * * ', () => this.runE2ETests()); cron.schedule('/2 * * * ', () => this.runAPITests()); cron.schedule('0 * * * *', () => this.runLoadTest()); }
async runE2ETests() { try { const metrics = await this.eMonitor.testUserFlow(); await this.recordResults('e2e-user-flow', metrics);
if (metrics.totalTime > this.alertThreshold) {
await this.sendAlert('e2e-user-flow', metrics);
}
} catch (error) {
console.error('E2E test failed:', error);
}
}
async runAPITests() { try { const authMetrics = await this.apiTests.testAuthenticationFlow(); const transactionMetrics = await this.apiTests.testTransactionFlow();
await this.recordResults('api-auth-flow', authMetrics);
await this.recordResults('api-transaction-flow', transactionMetrics);
if (authMetrics.status === 'failed' || transactionMetrics.status === 'failed') {
await this.sendAlert('api-tests', { authMetrics, transactionMetrics });
}
} catch (error) {
console.error('API test failed:', error);
}
}
async runLoadTest() { try { const results = await this.apiTests.testUnderLoad(10, 30000); await this.recordResults('load-test', results);
if (results.failedRequests > 0) {
await this.sendAlert('load-test', results);
}
} catch (error) {
console.error('Load test failed:', error);
}
}
async recordResults(testName, metrics) {
try {
await axios.post('http://monitoring-service/synthetic-results', {
testName,
timestamp: new Date(),
metrics
});
console.log(Recorded: ${testName}, metrics);
} catch (error) {
console.error('Failed to record results:', error);
}
}
async sendAlert(testName, metrics) {
try {
await axios.post('http://alerting-service/alerts', {
type: 'synthetic_monitoring',
testName,
severity: 'warning',
message: Synthetic test '${testName}' has issues,
metrics,
timestamp: new Date()
});
console.log(Alert sent for ${testName});
} catch (error) {
console.error('Failed to send alert:', error);
}
}
}
module.exports = ScheduledSyntheticMonitor;
Best Practices ✅ DO Test critical user journeys Simulate real browser conditions Monitor from multiple locations Track response times Alert on test failures Rotate test data Test mobile and desktop Include error scenarios ❌ DON'T Test with production data Reuse test accounts Skip timeout configurations Ignore test maintenance Test too frequently Hard-code credentials Ignore geographic variations Test only happy paths Key Metrics Response time Success rate Availability Core Web Vitals Error rate