18 Api Monitoring

// Example 1: Simple health check monitor
const http = require('http');

async function checkHealth() {
  const start = Date.now();

  return new Promise((resolve) => {
    const req = http.get('http://api.example.com/health', (res) => {
      let body = '';
      res.on('data', (chunk) => body += chunk);
      res.on('end', () => {
        const duration = Date.now() - start;
        resolve({
          status: res.statusCode,
          duration,
          body: JSON.parse(body),
          timestamp: new Date().toISOString()
        });
      });
    });

    req.on('error', (err) => {
      resolve({
        status: 0,
        duration: Date.now() - start,
        error: err.message,
        timestamp: new Date().toISOString()
      });
    });

    req.setTimeout(5000, () => {
      req.destroy();
      resolve({
        status: 0,
        duration: 5000,
        error: 'Timeout',
        timestamp: new Date().toISOString()
      });
    });
  });
}

async function monitorLoop() {
  setInterval(async () => {
    const result = await checkHealth();
    if (result.status !== 200 || result.duration > 2000) {
      console.error('Health check failed:', result);
      await sendAlert(result);
    }
  }, 30000);
}

# Example 2: Postman monitor configuration
# Postman Monitor runs this collection every 5 minutes
name: Production API Monitor
requests:
  - name: Health Check
    method: GET
    url: "{{base_url}}/health"
    tests: |
      pm.test("Status is 200", () => pm.response.to.have.status(200));
      pm.test("Response time < 2s", () => pm.expect(pm.response.responseTime).to.be.below(2000));

  - name: User Login Flow
    method: POST
    url: "{{base_url}}/auth/login"
    body:
      mode: raw
      raw: '{"username": "monitor", "password": "{{monitor_password}}"}'
    tests: |
      pm.test("Login successful", () => pm.response.to.have.status(200));
      pm.test("Token received", () => pm.expect(pm.response.json().token).to.be.a('string'));

  - name: Authenticated API Call
    method: GET
    url: "{{base_url}}/api/users/me"
    header:
      - key: Authorization
        value: "Bearer {{auth_token}}"
    tests: |
      pm.test("Authenticated call works", () => pm.response.to.have.status(200));

// Example 3: SLA validation with Prometheus metrics
const promClient = require('prom-client');

const apiAvailability = new promClient.Gauge({
  name: 'api_availability',
  help: 'API availability (1 = up, 0 = down)',
  labelNames: ['endpoint']
});

const apiLatency = new promClient.Gauge({
  name: 'api_latency_ms',
  help: 'API response latency in milliseconds',
  labelNames: ['endpoint']
});

async function monitorAndRecord() {
  const result = await checkEndpoint('/api/users');
  apiAvailability.set({ endpoint: '/api/users' }, result.status === 200 ? 1 : 0);
  apiLatency.set({ endpoint: '/api/users' }, result.duration);

  // Alert if SLA breached
  if (result.duration > 2000 || result.status !== 200) {
    await sendAlert({
      message: `SLA breach on /api/users`,
      duration: result.duration,
      status: result.status
    });
  }
}