Application Insights helper for typescript function apps

README.md

AppInsights helper

a typescript wrapper for Application Insights

Examples

Exception tracking

import { trackException } from './appinsights-helper'

trackException({ exception: error })

Trace tracking

trackTrace({ message: 'some message' ,  severity:  1 })
// severityLevels: Verbose = 0, Information = 1, Warning = 2, Error = 3, Critical = 4,

Advanced usage

HTTP request tracking:

import { markDependency, measureDependency } from './appinsights-helper'

const marker = markDependency('cosmos', 'query collection')
try {
  const url = 'https://domain.com/api/books'
  const locations = await requestPromise(url)
  measureDependency(marker, url)
} catch(ex) {
  measureDependency(marker, url, false)
  // could also trackException(ex) here
}

Cosmos query tracking:

dependency tracking is useful for measuring latency of remote calls (SQL, HTTP) and also failures

import { markDependency, measureDependency } from './appinsights-helper'

const marker = markDependency('cosmos', 'query collection')
try {
  const sql = 'select top 100 from c'
  const locations = await cosmosDb.items.query(sql) // pseudo-code cosmos query
  measureDependency(marker, sql)
} catch(ex) {
  measureDependency(marker, sql, false)
  // could also trackException(ex) here
}

Debug Event tracking

customEvents are powerful because you can query the logs by the customDimensions object

import { trackDebugEvent } from from './appinsights-helper'

// This 'debug' event will only log if the DEBUG_INSIGHTS="true" env var is set
trackDebugEvent({ name: 'new order',  properties: { order }, measurements: { productCount: order.products.length } }) 

appinsights-helper.ts

import * as appInsights from 'applicationinsights'
import { EventTelemetry, DependencyTelemetry, ExceptionTelemetry, MetricTelemetry, RequestTelemetry, TraceTelemetry } from 'applicationinsights/out/Declarations/Contracts'
appInsights.setup(process.env.APPINSIGHTS_INSTRUMENTATIONKEY).start()
export const aiClient = appInsights.defaultClient
aiClient.context.tags[aiClient.context.keys.cloudRole] = process.env.WEBSITE_SITE_NAME || 'defaultCloudRole'
const debugInsightsEnabled = (process.env.DEBUG_INSIGHTS === 'true') || false

export function trackEvent (telemetry: EventTelemetry): void { aiClient.trackEvent(telemetry) }
export function trackException (telemetry: ExceptionTelemetry): void { aiClient.trackException(telemetry) }
export function trackDependency (telemetry: DependencyTelemetry): void { aiClient.trackDependency(telemetry) }
export function trackTrace (telemetry: TraceTelemetry): void { aiClient.trackTrace(telemetry) }
export function trackRequest (telemetry: RequestTelemetry): void { aiClient.trackRequest(telemetry) }
export function trackMetric (telemetry: MetricTelemetry): void { aiClient.trackMetric(telemetry) }

interface IMarker {
  dependencyTypeName: string; // HTTP, SQL, etc
  name: string;
  startTime: number;
}

export function trackDebugEvent (telemetry: EventTelemetry): void {
  if (debugInsightsEnabled) {
    trackEvent(telemetry)
  }
}

export function markDependency (dependencyTypeName: string, name: string): IMarker {
  const startTime = Date.now()
  return { dependencyTypeName, name, startTime }
}

export function measureDependency (marker: IMarker, data = '', success = true): void {
  const { startTime, dependencyTypeName, name } = marker
  const duration = Date.now() - startTime
  const telemetry = { dependencyTypeName, name, duration, data, success } as DependencyTelemetry
  trackDependency(telemetry)
}

Overview of Application Insights Telemetry

Tables we care about for func apps...

• traces : context.log() & warn() & error()
• requests
• exceptions
• dependencies: remote db & http calls
• customEvents: allows use of logging JSON via { properties } that can be queried in Log Analytics
• customMetrics

App Insights - TelemetryTypes