feat: Added New Relic Control health check

lib/health-reporter.js

@@ -0,0 +1,168 @@
+/*
+ * Copyright 2024 New Relic Corporation. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+'use strict'
+
+const fs = require('node:fs')
+const crypto = require('node:crypto')
+const path = require('node:path')
+
+const defaultLogger = require('./logger').child({ component: 'HealthReporter' })
+
+const VALID_CODES = new Map([
+  ['NR-APM-000', 'Healthy.'],
+  ['NR-APM-001', 'Invalid license key.'],
+  ['NR-APM-002', 'License key missing.'],
+  ['NR-APM-003', 'Forced disconnect received from New Relic.'],
+  ['NR-APM-004', 'HTTP error communicating with New Relic.'],
+  ['NR-APM-005', 'Missing application name in agent configuration.'],
+  ['NR-APM-006', 'The maximum number of configured app names is exceeded.'],
+  ['NR-APM-007', 'HTTP proxy is misconfigured.'],
+  ['NR-APM-008', 'Agent is disabled via configuration.'],
+  ['NR-APM-009', 'Failed to connect to the New Relic data collector.'],
+  ['NR-APM-010', 'Agent config could not be parsed.'],
+  ['NR-APM-099', 'Agent has shutdown.']
+])
+
+function writeStatus({ file, healthy = true, code, msg, startTime, callback } = {}) {
+  const currentTime = Number(process.hrtime.bigint())
+  const yaml = [
+    `healthy: ${healthy}`,
+    `status: '${msg}'`,
+    `last_error: ${code}`,
+    `start_time_unix_nano: ${startTime}`,
+    `status_time_unix_nano: ${currentTime}`
+  ].join('\n')
+  fs.writeFile(file, yaml, { encoding: 'utf8' }, callback)
+}
+
+class HealthReporter {
+  #status = HealthReporter.STATUS_HEALTHY
+  #interval
+  #destFile
+  #logger
+  #startTime
+
+  static STATUS_HEALTHY = 'NR-APM-000'
+  static STATUS_INVALID_LICENSE_KEY = 'NR-APM-001'
+  static STATUS_LICENSE_KEY_MISSING = 'NR-APM-002'
+  static STATUS_FORCED_DISCONNECT = 'NR-APM-003'
+  static STATUS_BACKEND_ERROR = 'NR-APM-004'
+  static STATUS_MISSING_APP_NAME = 'NR-APM-005'
+  static STATUS_MAXIMUM_APP_NAMES_EXCEEDED = 'NR-APM-006'
+  static STATUS_HTTP_PROXY_MISCONFIGURED = 'NR-APM-007'
+  static STATUS_AGENT_DISABLED = 'NR-APM-008'
+  static STATUS_CONNECT_ERROR = 'NR-APM-009'
+  static STATUS_CONFIG_PARSE_FAILURE = 'NR-APM-010'
+  static STATUS_AGENT_SHUTDOWN = 'NR-APM-099'
+
+  constructor({ logger = defaultLogger, setInterval = global.setInterval } = {}) {
+    const fleetId = process.env.NEW_RELIC_SUPERAGENT_FLEET_ID
+    const outDir = process.env.NEW_RELIC_SUPERAGENT_HEALTH_DELIVERY_LOCATION
+    let checkInterval = process.env.NEW_RELIC_SUPERAGENT_HEALTH_FREQUENCY
+
+    this.#logger = logger
+
+    if (!fleetId) {
+      this.#logger.info('new relic control not present, skipping health reporting')
+      return
+    }
+
+    if (outDir === undefined) {
+      this.#logger.error('health check output directory not provided, skipping health reporting')
+      return
+    }
+
+    if (checkInterval === undefined) {
+      this.#logger.debug('health check interval not available, using default 5 seconds')
+      checkInterval = 5_000
+    } else {
+      checkInterval = parseInt(checkInterval, 10) * 1_000
+    }
+
+    this.#startTime = Number(process.hrtime.bigint())
+
+    const uuid = crypto.randomUUID().replaceAll('-', '')
+    this.#destFile = path.join(outDir, `health-${uuid}.yaml`)
+
+    this.#logger.info(
+      `new relic control is present, writing health on interval ${checkInterval} milliseconds to ${
+        this.#destFile
+      }`
+    )
+    this.#interval = setInterval(this.#healthCheck.bind(this), checkInterval)
+    this.#interval.unref()
+
+    this.#logger.info('health reporter initialized')
+  }
+
+  #healthCheck() {
+    const healthy = this.#status === HealthReporter.STATUS_HEALTHY
+    writeStatus({
+      file: this.#destFile,
+      healthy,
+      startTime: this.#startTime,
+      code: this.#status,
+      msg: VALID_CODES.get(this.#status),
+      callback: (error) => {
+        if (error) {
+          this.#logger.error(`error when writing out health status: ${error.message}`)
+        }
+      }
+    })
+  }
+
+  setStatus(status) {
+    if (VALID_CODES.has(status) === false) {
+      // TODO: if we ever add codes in our reserved block (300-399), account for them here
+      this.#logger.warn(`invalid health reporter status provided: ${status}`)
+      return
+    }
+
+    if (
+      status === HealthReporter.STATUS_AGENT_SHUTDOWN &&
+      this.#status !== HealthReporter.STATUS_HEALTHY
+    ) {
+      this.#logger.info(
+        `not setting shutdown health status due to current status code: ${this.#status}`
+      )
+      return
+    }
+
+    this.#status = status
+  }
+
+  stop() {
+    clearInterval(this.#interval)
+
+    const healthy = this.#status === HealthReporter.STATUS_HEALTHY
+    let code = this.#status
+    let msg = VALID_CODES.get(code)
+    if (healthy === true) {
+      // We only update the status on shutdown when the last known state is
+      // the healthy state. Otherwise, we need to leave the current code in
+      // place, and just update the report time.
+      code = HealthReporter.STATUS_AGENT_SHUTDOWN
+      msg = VALID_CODES.get(code)
+    }
+
+    writeStatus({
+      file: this.#destFile,
+      startTime: this.#startTime,
+      healthy,
+      code,
+      msg,
+      callback: (error) => {
+        if (error) {
+          this.#logger.error(
+            `error when writing out health status during shutdown: ${error.message}`
+          )
+        }
+      }
+    })
+  }
+}
+
+module.exports = HealthReporter

package.json

@@ -193,6 +193,9 @@
   "bin": {
     "newrelic-naming-rules": "./bin/test-naming-rules.js"
   },
+  "imports": {
+    "#agentlib/*.js": "./lib/*.js"
+  },
   "dependencies": {
     "@grpc/grpc-js": "^1.12.2",
     "@grpc/proto-loader": "^0.7.5",