OpenTelemetry Metrics

DD_METRICS_OTEL_ENABLED=true node app.js

require('dd-trace').init()
const { metrics } = require('@opentelemetry/api')

const meter = metrics.getMeter('my-service', '1.0.0')

const requestCounter = meter.createCounter('http.requests', {
  description: 'Total HTTP requests',
  unit: 'requests',
})

// Record a value with attributes
requestCounter.add(1, { method: 'GET', status: 200 })

const durationHistogram = meter.createHistogram('http.duration', {
  description: 'HTTP request duration',
  unit: 'ms',
})

durationHistogram.record(145, { route: '/api/users' })

const connectionCounter = meter.createUpDownCounter('active.connections', {
  description: 'Active connections',
  unit: 'connections',
})

connectionCounter.add(1)   // New connection
connectionCounter.add(-1)  // Connection closed

const cpuGauge = meter.createObservableGauge('system.cpu.usage', {
  description: 'CPU usage percentage',
  unit: 'percent',
})

cpuGauge.addCallback((result) => {
  const cpuUsage = process.cpuUsage()
  result.observe(cpuUsage.system / 1_000_000, { core: '0' })
})

require('dd-trace').init()
const { metrics } = require('@opentelemetry/api')

const meter = metrics.getMeter('my-service', '1.0.0')

// Counters
const requestCounter = meter.createCounter('http.requests')
const errorCounter = meter.createCounter('http.errors')

// Histogram
const latencyHistogram = meter.createHistogram('http.latency', { unit: 'ms' })

// UpDownCounter
const activeRequests = meter.createUpDownCounter('http.active_requests')

app.use((req, res, next) => {
  const start = Date.now()
  activeRequests.add(1)

  res.on('finish', () => {
    const duration = Date.now() - start
    const labels = { method: req.method, status: res.statusCode }

    requestCounter.add(1, labels)
    latencyHistogram.record(duration, labels)
    activeRequests.add(-1)

    if (res.statusCode >= 500) {
      errorCounter.add(1, labels)
    }
  })

  next()
})