Add Node.js monitoring template

node_js/env.js

@@ -0,0 +1,35 @@
+/** InfluxDB URL */
+const INFLUX_URL = process.env.INFLUX_URL || 'http://localhost:8086'
+/** InfluxDB authorization token */
+const INFLUX_TOKEN = process.env.INFLUX_TOKEN || 'my-token'
+/** Organization within InfluxDB  */
+const INFLUX_ORG = process.env.INFLUX_ORG || 'my-org'
+/** InfluxDB bucket  */
+const INFLUX_BUCKET = 'iot_center'
+
+// Defaults when on boarding a fresh new InfluxDB instance
+/** InfluxDB user  */
+const onboarding_username = 'my-user'
+/** InfluxDB password  */
+const onboarding_password = 'my-password'
+
+/** recommended interval for client's to refresh configuration in seconds */
+const configuration_refresh = 3600
+
+function logEnvironment() {
+  console.log(`INFLUX_URL=${INFLUX_URL}`)
+  console.log(`INFLUX_TOKEN=${INFLUX_TOKEN ? '***' : ''}`)
+  console.log(`INFLUX_ORG=${INFLUX_ORG}`)
+  console.log(`INFLUX_BUCKET=${INFLUX_BUCKET}`)
+}
+
+module.exports = {
+  INFLUX_URL,
+  INFLUX_TOKEN,
+  INFLUX_ORG,
+  onboarding_username,
+  onboarding_password,
+  configuration_refresh,
+  INFLUX_BUCKET,
+  logEnvironment,
+}

node_js/monitor.js

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+const {InfluxDB, Point} = require('@influxdata/influxdb-client')
+const {
+  INFLUX_URL: url,
+  INFLUX_TOKEN: token,
+  INFLUX_ORG: org,
+  INFLUX_BUCKET: bucket,
+} = require('./env')
+const responseTime = require('response-time')
+
+// create Influx Write API to report application monitoring data
+const writeAPI = new InfluxDB({url, token}).getWriteApi(org, bucket, 'ns', {
+  defaultTags: {
+    service: 'iot_center',
+    host: require('os').hostname(),
+  },
+})
+// write node resource/cpu/memory usage
+function writeProcessUsage() {
+  function createPoint(measurement, usage) {
+    const point = new Point(measurement)
+    for (const key of Object.keys(usage)) {
+      point.floatField(key, usage[key])
+    }
+    return point
+  }
+
+  // https://nodejs.org/api/process.html#process_process_memoryusage
+  writeAPI.writePoint(createPoint('node_memory_usage', process.memoryUsage()))
+  // https://nodejs.org/api/process.html#process_process_cpuusage_previousvalue
+  writeAPI.writePoint(createPoint('node_cpu_usage', process.cpuUsage()))
+  // https://nodejs.org/api/process.html#process_process_resourceusage
+  writeAPI.writePoint(
+    createPoint('node_resource_usage', process.resourceUsage())
+  )
+}
+// write process usage now and then every 10 seconds
+writeProcessUsage()
+const nodeUsageTimer = setInterval(writeProcessUsage, 10_000).unref()
+
+// on shutdown
+// - clear reporting of node usage
+// - flush unwritten points and cancel retries
+async function onShutdown() {
+  clearInterval(nodeUsageTimer)
+  try {
+    await writeAPI.close()
+  } catch (error) {
+    console.error('ERROR: Application monitoring', error)
+  }
+  // eslint-disable-next-line no-process-exit
+  process.exit(0)
+}
+process.on('SIGINT', onShutdown)
+process.on('SIGTERM', onShutdown)
+
+// export a monitoring function for express.js response time monitoring
+module.exports = function (app) {
+  app.use(
+    responseTime((req, res, time) => {
+      // print out request basics
+      console.info(
+        `${req.method} ${req.path} ${res.statusCode} ${
+          Math.round(time * 100) / 100
+        }ms`
+      )
+      // write response time to InfluxDB
+      const point = new Point('express_http_server')
+        .tag('uri', req.path)
+        .tag('method', req.method)
+        .tag('status', String(res.statusCode))
+        .floatField('response_time', time)
+      writeAPI.writePoint(point)
+    })
+  )
+}