How Insightful! Grok Your ASP.NET Core Web Apps with Application Insights

Thanks so much for attending my talk! I hope you found it informative and enjoyable. I've gathered information to help you get started with Application Insights and ASP.NET Core.

Instrument your application

I've written instructions in this repository for instrumenting your app to gather:

• Server-side telemetry (run time and build time)
• Client-side telemetry (browser)
• Debug snapshots

Server-side telemetry

• Activate the extension (Azure) or Application Insights Status Monitor from Web Platform Installer (IIS)
• Install NuGet Package - Microsoft.ApplicationInsights.AspNetCore

Client-side telemetry

Make the following changes to _Layout.cshtml.

Razor directives (top of page):

@using Microsoft.Extensions.Configuration
@inject IConfiguration Configuration

Script block (insert as the last element before </head>)

<script type="text/javascript">
	var appInsights = window.appInsights || function (a) {
		function b(a) { c[a] = function () { var b = arguments; c.queue.push(function () { c[a].apply(c, b) }) } } var c = { config: a }, d = document, e = window; setTimeout(function () { var b = d.createElement("script"); b.src = a.url || "https://az416426.vo.msecnd.net/scripts/a/ai.0.js", d.getElementsByTagName("script")[0].parentNode.appendChild(b) }); try { c.cookie = d.cookie } catch (a) { } c.queue = []; for (var f = ["Event", "Exception", "Metric", "PageView", "Trace", "Dependency"]; f.length;)b("track" + f.pop()); if (b("setAuthenticatedUserContext"), b("clearAuthenticatedUserContext"), b("startTrackEvent"), b("stopTrackEvent"), b("startTrackPage"), b("stopTrackPage"), b("flush"), !a.disableExceptionTracking) { f = "onerror", b("_" + f); var g = e[f]; e[f] = function (a, b, d, e, h) { var i = g && g(a, b, d, e, h); return !0 !== i && c["_" + f](a, b, d, e, h), i } } return c
	}({
		instrumentationKey: "@Configuration.GetSection("ApplicationInsights")["InstrumentationKey"]"
	});

	window.appInsights = appInsights, appInsights.queue && 0 === appInsights.queue.length && appInsights.trackPageView();
</script>

Snapshot Debugging

Install NuGet Package - Microsoft.ApplicationInsights.SnapshotCollector

Add these using directives to Startup.cs:

using Microsoft.ApplicationInsights.AspNetCore;
using Microsoft.ApplicationInsights.Extensibility;
using Microsoft.Extensions.Options;
using Microsoft.ApplicationInsights.SnapshotCollector;

Add this block to Startup.ConfigureServices:

// Configure SnapshotCollector from application settings
services.Configure<SnapshotCollectorConfiguration>(Configuration.GetSection(nameof(SnapshotCollectorConfiguration)));

// Add SnapshotCollector telemetry processor.
services.AddSingleton<ITelemetryProcessorFactory>(sp => new SnapshotCollectorTelemetryProcessorFactory(sp));

Add this private class within the Startup class:

private class SnapshotCollectorTelemetryProcessorFactory : ITelemetryProcessorFactory
{
	private readonly IServiceProvider _serviceProvider;

	public SnapshotCollectorTelemetryProcessorFactory(IServiceProvider serviceProvider) =>
		_serviceProvider = serviceProvider;

	public ITelemetryProcessor Create(ITelemetryProcessor next)
	{
		var snapshotConfigurationOptions = _serviceProvider.GetService<IOptions<SnapshotCollectorConfiguration>>();
		return new SnapshotCollectorTelemetryProcessor(next, configuration: snapshotConfigurationOptions.Value);
	}
}

Add this configuration to appsettings.json:

  "SnapshotCollectorConfiguration": {
    "IsEnabledInDeveloperMode": false,
    "ThresholdForSnapshotting": 1,
    "MaximumSnapshotsRequired": 3,
    "MaximumCollectionPlanSize": 50,
    "ReconnectInterval": "00:15:00",
    "ProblemCounterResetInterval": "1.00:00:00",
    "SnapshotsPerTenMinutesLimit": 1,
    "SnapshotsPerDayLimit": 30,
    "SnapshotInLowPriorityThread": true,
    "ProvideAnonymousTelemetry": true,
    "FailedRequestLimit": 3
  }

Running the demos

.\Demos\MoviePortal_Instrumented\RazorPagesMovie.sln is the fully instrumented demo, but you can recreate the full demo using .\Demos\MoviePortal_NOT_Instrumented\RazorPagesMovie.sln. Deploy MovieNewsService somewhere and add the URL to the appropriate spot in appsettings.json. Be sure to add your own instrumentation key!

Additional reading

• What is Application Insights?
• Supported platforms and frameworks
• Application Insights Quickstart for ASP.NET Core
• Azure Monitor documentation
• More information on the difference between run time and build time telemetry ingestion
• About Adaptive Sampling