ServiceNow XMLStats Synthetic Polling

snow-xmlstats-synthetic.js

/* <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> */
/* Imports                                                                    */
/* <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> */

const assert = require('assert'),
  { promisify } = require('util'),
  { Parser, processors } = require('xml2js'),
  got = require('got'),
  { Cookie, CookieJar } = require('tough-cookie')

/* <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> */
/* Config                                                                     */
/* <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> */

var SNOW_URL = $secure.SNOW_URL; //base ServiceNow URL
var SNOW_USER = $secure.SNOW_USER;
var SNOW_PASS = $secure.SNOW_PASS;
var NR_INGEST_KEY = $secure.NR_INGEST_KEY;


/* <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> */
/* Constants                                                                  */
/* <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> */

const TYPES = { // Available metric types
    GAUGE: 'gauge',
    COUNT: 'count',
    SUMMARY: 'summary',
  },
  FREQUENCY = 300000,    // This value needs to match the monitor frequency - ms
  PREFIX = "servicenow", // Prefix to all metric names reported to New Relic
  DEBUG = false // Log output for debugging

  /* Add your handler function(s) to this array for it to be invoked by the main collector logic. */
  const HANDLERS = [
    collectServletMetrics,
    collectSemaphoreMetrics
  ]

  /* Add any includes that you require for your handlers here. These will be included in the call to the XMLstats interface as filters: xmlstats.do?includes=servlet,sessionsummary,semaphores */
  const INCLUDES = [
    'semaphores',
    'servlet',
    'sessionsummary',
  ]



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/* Utility functions                                                          */
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/**
 * Create a metric in a form suitable for the metric API.
 *
 * @param timestamp  the timestamp for the metric
 * @param name       the metric name
 * @param type       the metric type
 * @param value      the value for the metric
 * @param attributes the dimensional attributes to add on the metric
 */
function createMetric(timestamp, name, type, value, attributes) {
  const metric = {
    timestamp,
    name: `${PREFIX}.${name}`,
    type,
    value,
    attributes,
  }

  if (type === TYPES.COUNT || type === TYPES.SUMMARY) {
    metric['interval.ms'] = FREQUENCY
  }

  return metric
}

/**
 * Add a metric to the set of metrics whose value is the value of key in obj.
 * If key is not in obj, do nothing. This is a convenience method so the
 * collection handlers aren't littered with `if` checks.
 *
 * @param metricSet  a set of metric objects formatted for the metric API
 * @param timestamp  the timestamp for the metric
 * @param obj        the object to inspect for the named metric key/value pair
 * @param key        the key to look for in obj
 * @param type       the metric type
 * @param attributes the dimensional attributes to add on the metric
 * @param name       the metric name or null to use the key as the name
 */
function addMetric(metricSet, timestamp, obj, key, type, attributes, name = null) {
  if (typeof obj[key] !== 'undefined') {
    const val = Array.isArray(obj[key]) ? obj[key][0] : obj[key]
    metricSet.push(createMetric(timestamp, name || key, type, val, attributes))
  }
}

/**
 * Add a dimension key/value pair to the set of dimensions whose value is the
 * value of key in obj. If key is not in obj, do nothing. This is a convenience
 * method so the collection handlers aren't littered with `if` checks.
 *
 * @param dimensions an object of key/value pairs representing dimensions to add to a metric
 * @param obj        the object to inspect for the named metric key/value pair
 * @param key        the key to look for in obj
 * @param name       the attribute name or null to use the key as the name
 */
function addDimension(dimensions, obj, key, name = null) {
  if (typeof obj[key] !== 'undefined') {
    const val = Array.isArray(obj[key]) ? obj[key][0] : obj[key]
    dimensions[name || key] = val
  }
}

/**
 * Push the given array of metrics to the metrics API.
 *
 * @param metrics an array of metrics suitable for the metrics API
 */
async function pushMetrics(metrics) {
  DEBUG && console.log(metrics)

  const {
    body,
    statusCode
  } = await got.post('https://metric-api.newrelic.com/metric/v1', {
    json: [{ metrics }],
    headers: { 'Api-Key': NR_INGEST_KEY},
    responseType: 'json',
  })

  if (statusCode !== 202) {
    throw new Error('metrics could not be posted')
  }

  if (!body.requestId) {
    throw new Error('invalid response: no requestId')
  }

  console.log(`posted ${metrics.length} metrics with requestId: ${body.requestId}`)
}

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/* Handler functions                                                          */
/*                                                                            */
/* This is where you would add logic to collect additional metrics. Handler   */
/* functions have the signature (timestamp, xmlstatsJson) -> []metrics.       */
/*                                                                            */
/* You should not need to modify anything else in this script except the      */
/* handlers in this section. Everything else should be handled for you.       */
/* <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> */

/**
 * Parse the servlet metrics out of the full JSON results.
 *
 * @param ts  the timestamp to use for creating metrics
 * @param doc the JSON document converted from the xmlstats.do call
 * @returns array of metrics
 */
function collectServletMetrics(ts, doc) {
  const metrics = [],
    dimensions = {}

  addDimension(dimensions, doc, 'servlet.info')
  addDimension(dimensions, doc, 'servlet.node_id')
  addDimension(dimensions, doc, 'servlet.hostname')
  addDimension(dimensions, doc, 'servlet.port')

  addMetric(metrics, ts, doc, 'servlet.cache.flushes', TYPES.COUNT, dimensions)
  addMetric(metrics, ts, doc, 'servlet.uptime', TYPES.COUNT, dimensions)
  addMetric(metrics, ts, doc, 'servlet.transactions', TYPES.COUNT, dimensions)
  addMetric(metrics, ts, doc, 'servlet.errors.handled', TYPES.COUNT, dimensions)
  addMetric(metrics, ts, doc, 'servlet.processor.transactions', TYPES.COUNT, dimensions)
  addMetric(metrics, ts, doc, 'servlet.cancelled.transactions', TYPES.COUNT, dimensions)
  addMetric(metrics, ts, doc, 'servlet.active.sessions', TYPES.GAUGE, dimensions)

  const sessions = doc['sessionsummary']

  if (sessions && sessions.$) {
    const $ = sessions.$

    addMetric(metrics, ts, $, 'logged_in', TYPES.GAUGE, dimensions, 'servlet.sessions.logged_in')
    addMetric(metrics, ts, $, 'end_user', TYPES.GAUGE, dimensions, 'servlet.sessions.end_user')
    addMetric(metrics, ts, $, 'total', TYPES.GAUGE, dimensions, 'servlet.sessions.total')
  }

  function addMetricGroup(obj, key, name) {
    const aggregations = {
      one: '1m',
      five: '5m',
      fifteen: '15m',
      hour: '1h',
      daily: '1d'
    }

    if (!obj[key]) {
      return
    }

    for (aggr in aggregations) {
      if (!obj[key][aggr]) {
        continue
      }

      const aggrObj = obj[key][aggr]

      if (!aggrObj.$) {
        continue
      }

      const basename = `${name}.duration.${aggregations[aggr]}`

      addMetric(metrics, ts, aggrObj.$, 'count', TYPES.GAUGE, dimensions, `${name}.${aggregations[aggr]}`)
      addMetric(metrics, ts, aggrObj.$, 'mean', TYPES.GAUGE, dimensions, `${basename}.mean`)
      addMetric(metrics, ts, aggrObj.$, 'median', TYPES.GAUGE, dimensions, `${basename}.median`)
      addMetric(metrics, ts, aggrObj.$, 'ninetypercent', TYPES.GAUGE, dimensions, `${basename}.ninetypercent`)
    }
  }

  const servletMetrics = doc['servlet.metrics']

  if (servletMetrics) {
    addMetricGroup(servletMetrics, 'transactions', 'servlet.transactions.server')
    addMetricGroup(servletMetrics, 'client_transactions', 'servlet.transactions.client')
    addMetricGroup(servletMetrics, 'client_network_times', 'servlet.transactions.client_network')
    addMetricGroup(servletMetrics, 'client_browser_times', 'servlet.transactions.client_browser')
    addMetricGroup(servletMetrics, 'amb_transactions', 'servlet.transactions.amb_server')
  }

  return metrics
}

function collectSemaphoreMetrics(ts, doc) {
  const metrics = [];
  let nodeId, hostname = null;

  if (doc['servlet.node_id']) {
    nodeId = doc['servlet.node_id'];
  }
  if (doc['servlet.hostname']) {
    hostname = doc['servlet.hostname'];
  }

  const semaphoreMetrics = doc['semaphores'];

  if (semaphoreMetrics && semaphoreMetrics.length > 0) {
    for (s of semaphoreMetrics) {
      if (s.$) {
        let $ = s.$;
        addMetric(metrics, ts, $, 'available', TYPES.GAUGE, {'servlet.hostname': hostname, 'servlet.node_id': nodeId, 'semaphore.name': $.name}, 'semaphores.available')
        addMetric(metrics, ts, $, 'max_queue_depth', TYPES.GAUGE, {'servlet.hostname': hostname, 'servlet.node_id': nodeId, 'semaphore.name': $.name}, 'semaphores.max_queue_depth')
        addMetric(metrics, ts, $, 'queue_depth', TYPES.GAUGE, {'servlet.hostname': hostname, 'servlet.node_id': nodeId, 'semaphore.name': $.name}, 'semaphores.queue_depth')
        addMetric(metrics, ts, $, 'rejected_executions', TYPES.GAUGE, {'servlet.hostname': hostname, 'servlet.node_id': nodeId, 'semaphore.name': $.name}, 'semaphores.rejected_executions')
        addMetric(metrics, ts, $, 'maximum_concurrency', TYPES.GAUGE, {'servlet.hostname': hostname, 'servlet.node_id': nodeId, 'semaphore.name': $.name}, 'semaphores.maximum_concurrency')
      }
    }
  }

  return metrics;
}


/* <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> */
/* Collector Logic                                                            */
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/**
 * Hit the xmlstats.do endpoint to gather all the metrics for the specified
 * namespaces and invoke all the handlers.
 */
async function collectXmlStats() {
  const xmlStatsUrl = SNOW_URL + `xmlstats.do?include=${INCLUDES.join(',')}`,
    cookieJar = await getCookies(xmlStatsUrl),
    response = await got(xmlStatsUrl, { cookieJar }),
    parser = new Parser({
      explicitArray: false,
      valueProcessors: [processors.parseNumbers, processors.parseBooleans],
      attrValueProcessors: [processors.parseNumbers, processors.parseBooleans],
    }),
    result = await parser.parseStringPromise(response.body)

  if (!result.xmlstats) {
    console.warn('no xmlstats element detected in xmlstats.do response')
    return []
  }

  const xmlstats = result.xmlstats,
    now = new Date().getTime()
  let metrics = []

  DEBUG && console.log(xmlstats);

  HANDLERS.forEach(fn => {
    metricSet = fn(now, xmlstats)

    if (metricSet && metricSet.length > 0) {
      metrics = [ ...metrics, ...metricSet ]
    }
  })

  return metrics
}

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/* Login Logic                                                                */
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/**
 * Grab the current cookies for the current page loaded in the browser.
 *
 * @param url url for the cookie jar
 * @returns an array of cookies as JSON objects
 */
async function getCookies(url) {
  const cookies = await $webDriver.manage().getCookies(),
    cookieJar = new CookieJar();
	  setCookie = promisify(cookieJar.setCookie.bind(cookieJar));

  for (let index = 0; index < cookies.length; index += 1) {
    const ck = new Cookie({ ...cookies[index], key: cookies[index].name })
    await setCookie(ck, url)
  }

  return cookieJar
}

/**
 * Login to the SNOW instance using the SNOW URL, user, and password
 * secure credentials.
 */
async function login() {
  await $webDriver.get(SNOW_URL)

  const userName = await $webDriver.findElement($selenium.By.id('user_name'))

  await userName.clear()
  await userName.sendKeys(SNOW_USER)

  const password = await $webDriver.findElement($selenium.By.id('user_password'))

  await password.clear()
  await password.sendKeys(SNOW_PASS)

  await $webDriver.findElement($selenium.By.id('sysverb_login')).click()
}

/* <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> */
/* Main Logic                                                                 */
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/**
 * Run the synthetic logic.
 */
async function main() {
  /* Login to the SNOW server */
  await login()

  /* Hit the `xmlstats.do` endpoint to collect the stats */
  const metrics = await collectXmlStats();

  if (!metrics || metrics.length === 0) {
    console.warn('no metrics collected')
    return
  }

  /* Post the metrics back to New Relic */
  await pushMetrics(metrics)
}

/* Invoke the synthetic logic */

main()