Monitor Queue Stats in Azure via Azure Functions

function.json

{
 "disabled": false,
 "scriptFile": "../dist/CheckQueues/index.js",
 "bindings": [
  {
    "schedule": "*/15 * * * * *",
    "name": "snapshotSidekiqQueues",
    "type": "timerTrigger",
    "direction": "in"
  }
 ],
 "_originalEntryPoint": false,
 "_originalScriptFile": "../dist/CheckQueues/index.js",
 "entryPoint": "CheckQueues"
}

index.js

import { TelemetryClient } from 'applicationinsights'
import { promisify } from 'util'
import _ from 'lodash'

import Redis from 'redis'

module.exports = async function (context, req) {

  const appInsightsKey = process.env['ApplicationInsightsKey']
  const insightsClient = new TelemetryClient(appInsightsKey);

  const redis_url = process.env['ConnectionStrings:RedisConnection'] || process.env['CUSTOMCONNSTR_RedisConnection']

  const redis_url_url = URL.parse(redis_url);
  const redis_host = redis_url_url.hostname;

  const client = Redis.createClient(redis_url, {tls: {servername: redis_host}, detect_buffers: true});
  const smembersAsync = promisify(client.smembers).bind(client)
  const lrangeAsync = promisify(client.lrange).bind(client)
  const llenAsync = promisify(client.llen).bind(client)

  const queues = await smembersAsync('queues')

  _.each(queues, async (queue) => {
    const queueName = `queue:${queue}`
    const lastJobRaw = await lrangeAsync(queueName, -1, -1)
    let latency = 0
    if (lastJobRaw.length == 1) {
      const lastJob = JSON.parse(lastJobRaw[0])
      const now = new Date() / 1000;
      const thence = lastJob["enqueued_at"] || now
      latency = now - thence
    }
    const queueSize = await llenAsync(queueName)
    await insightsClient.trackMetric({name: `${queueName}:latency`, value: latency})
    await insightsClient.trackMetric({name: `${queueName}:size`, value: queueSize})
  })

  await insightsClient.flush()
  // Write values out to AppInsights

  context.res = {
    status: 200,
    body: 'OK!'
  }
}