Application Insights for ASP.NET Core applications

This article describes how to enable Application Insights for an ASP.NET Core application. When you complete the instructions in this article, Application Insights will collect requests, dependencies, exceptions, performance counters, heartbeats, and logs from your ASP.NET Core application.

The example we'll use here is an MVC application that targets netcoreapp3.0. You can apply these instructions to all ASP.NET Core applications. If you are using the Worker Service, use the instructions from here.

Note

A preview OpenTelemetry-based .NET offering is available. Learn more.

Supported scenarios

The Application Insights SDK for ASP.NET Core can monitor your applications no matter where or how they run. If your application is running and has network connectivity to Azure, telemetry can be collected. Application Insights monitoring is supported everywhere .NET Core is supported. Support covers the following:

  • Operating system: Windows, Linux, or Mac
  • Hosting method: In process or out of process
  • Deployment method: Framework dependent or self-contained
  • Web server: IIS (Internet Information Server) or Kestrel
  • Hosting platform: The Web Apps feature of Azure App Service, Azure VM, Docker, Azure Kubernetes Service (AKS), and so on
  • .NET Core version: All officially supported .NET Core versions that are not in preview
  • IDE: Visual Studio, Visual Studio Code, or command line

Note

ASP.NET Core 3.1 requires Application Insights 2.8.0 or later.

Prerequisites

  • A functioning ASP.NET Core application. If you need to create an ASP.NET Core application, follow this ASP.NET Core tutorial.
  • A valid Application Insights instrumentation key. This key is required to send any telemetry to Application Insights. If you need to create a new Application Insights resource to get an instrumentation key, see Create an Application Insights resource.

Important

Connection Strings are recommended over instrumentation keys. New Azure regions require using connection strings instead of instrumentation keys. Connection string identifies the resource that you want to associate your telemetry data with. It also allows you to modify the endpoints your resource will use as a destination for your telemetry. You will need to copy the connection string and add it to your application's code or to an environment variable.

Enable Application Insights server-side telemetry (Visual Studio)

For Visual Studio for Mac, use the manual guidance. Only the Windows version of Visual Studio supports this procedure.

  1. Open your project in Visual Studio.

    Tip

    To track all the changes that Application Insights makes, you can set up source control for your project. To set it up, select File > Add to Source Control.

  2. Select Project > Add Application Insights Telemetry.

  3. Select Get Started. Depending on your version of Visual Studio, the name of this button might vary. In some earlier versions, it is named the Start Free button.

  4. Select your subscription, and then select Resource > Register.

  5. After you add Application Insights to your project, check to confirm that you're using the latest stable release of the SDK. Go to Project > Manage NuGet Packages > Microsoft.ApplicationInsights.AspNetCore. If you need to, select Update.

    Screenshot showing where to select the Application Insights package for update

  6. If you added your project to source control, go to View > Team Explorer > Changes. You can select each file to see a diff view of the changes made by Application Insights telemetry.

Enable Application Insights server-side telemetry (no Visual Studio)

  1. Install the Application Insights SDK NuGet package for ASP.NET Core. We recommend that you always use the latest stable version. Find full release notes for the SDK on the open-source GitHub repo.

    The following code sample shows the changes to be added to your project's .csproj file.

        <ItemGroup>
          <PackageReference Include="Microsoft.ApplicationInsights.AspNetCore" Version="2.16.0" />
        </ItemGroup>
    
  2. Add services.AddApplicationInsightsTelemetry(); to the ConfigureServices() method in your Startup class, as in this example:

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            // The following line enables Application Insights telemetry collection.
            services.AddApplicationInsightsTelemetry();
    
            // This code adds other services for your application.
            services.AddMvc();
        }
    
  3. Set up the instrumentation key.

    Although you can provide the instrumentation key as an argument to AddApplicationInsightsTelemetry, we recommend that you specify the instrumentation key in configuration. The following code sample shows how to specify an instrumentation key in appsettings.json. Make sure appsettings.json is copied to the application root folder during publishing.

        {
          "ApplicationInsights": {
            "InstrumentationKey": "putinstrumentationkeyhere"
          },
          "Logging": {
            "LogLevel": {
              "Default": "Warning"
            }
          }
        }
    

    Alternatively, specify the instrumentation key in either of the following environment variables:

    • APPINSIGHTS_INSTRUMENTATIONKEY

    • ApplicationInsights:InstrumentationKey

    For example:

    • SET ApplicationInsights:InstrumentationKey=putinstrumentationkeyhere

    • SET APPINSIGHTS_INSTRUMENTATIONKEY=putinstrumentationkeyhere

    • Typically, APPINSIGHTS_INSTRUMENTATIONKEY is used in Azure Web Apps, but it can also be used in all places where this SDK is supported. (If you're doing codeless web app monitoring, this format is required if you aren't using connection strings.)

    In lieu of setting instrumentation keys, you can now also use Connection Strings.

    Note

    An instrumentation key specified in code wins over the environment variable APPINSIGHTS_INSTRUMENTATIONKEY, which wins over other options.

User secrets and other configuration providers

If you want to store the instrumentation key in ASP.NET Core user secrets or retrieve it from another configuration provider, you can use the overload with a Microsoft.Extensions.Configuration.IConfiguration parameter. For example, services.AddApplicationInsightsTelemetry(Configuration);. Starting from Microsoft.ApplicationInsights.AspNetCore version 2.15.0, calling services.AddApplicationInsightsTelemetry() automatically reads the instrumentation key from Microsoft.Extensions.Configuration.IConfiguration of the application. There is no need to explicitly provide the IConfiguration.

Run your application

Run your application and make requests to it. Telemetry should now flow to Application Insights. The Application Insights SDK automatically collects incoming web requests to your application, along with the following telemetry.

Live Metrics

Live Metrics can be used to quickly verify if Application Insights monitoring is configured correctly. It might take a few minutes for telemetry to appear in the portal and analytics, but Live Metrics shows CPU usage of the running process in near real time. It can also show other telemetry like Requests, Dependencies, and Traces.

ILogger logs

The default configuration collects ILogger Warning logs and more severe logs. You can customize this configuration.

Dependencies

Dependency collection is enabled by default. This article explains the dependencies that are automatically collected, and also contain steps to do manual tracking.

Performance counters

Support for performance counters in ASP.NET Core is limited:

  • SDK versions 2.4.1 and later collect performance counters if the application is running in Azure Web Apps (Windows).
  • SDK versions 2.7.1 and later collect performance counters if the application is running in Windows and targets NETSTANDARD2.0 or later.
  • For applications targeting the .NET Framework, all versions of the SDK support performance counters.
  • SDK Versions 2.8.0 and later support cpu/memory counter in Linux. No other counter is supported in Linux. The recommended way to get system counters in Linux (and other non-Windows environments) is by using EventCounters.

EventCounter

By default, EventCounterCollectionModule is enabled. To learn how to configure the list of counters to be collected, see EventCounters introduction.

Enable client-side telemetry for web applications

The preceding steps are enough to help you start collecting server-side telemetry. If your application has client-side components, follow the next steps to start collecting usage telemetry.

  1. In _ViewImports.cshtml, add injection:
    @inject Microsoft.ApplicationInsights.AspNetCore.JavaScriptSnippet JavaScriptSnippet
  1. In _Layout.cshtml, insert HtmlHelper at the end of the <head> section but before any other script. If you want to report any custom JavaScript telemetry from the page, inject it after this snippet:
    @Html.Raw(JavaScriptSnippet.FullScript)
    </head>

As an alternative to using the FullScript, the ScriptBody is available starting in Application Insights SDK for ASP.NET Core version 2.14. Use this if you need to control the <script> tag to set a Content Security Policy:

 <script> // apply custom changes to this script tag.
     @Html.Raw(JavaScriptSnippet.ScriptBody)
 </script>

The .cshtml file names referenced earlier are from a default MVC application template. Ultimately, if you want to properly enable client-side monitoring for your application, the JavaScript snippet must appear in the <head> section of each page of your application that you want to monitor. To do this in this application template, add the JavaScript snippet to _Layout.cshtml.

If your project doesn't include _Layout.cshtml, you can still add client-side monitoring. To do this, add the JavaScript snippet to an equivalent file that controls the <head> of all pages within your app. Or you can add the snippet to multiple pages, but this solution is difficult to maintain and we generally don't recommend it.

Note

JavaScript injection provides a default configuration experience. If you require configuration beyond setting the instrumentation key, you are required to remove auto-injection as described above and manually add the JavaScript SDK.

Configure the Application Insights SDK

You can customize the Application Insights SDK for ASP.NET Core to change the default configuration. Users of the Application Insights ASP.NET SDK might be familiar with changing configuration by using ApplicationInsights.config or by modifying TelemetryConfiguration.Active. For ASP.NET Core, make almost all configuration changes in the ConfigureServices() method of your Startup.cs class, unless you're directed otherwise. The following sections offer more information.

Note

In ASP.NET Core applications, changing configuration by modifying TelemetryConfiguration.Active isn't supported.

Using ApplicationInsightsServiceOptions

You can modify a few common settings by passing ApplicationInsightsServiceOptions to AddApplicationInsightsTelemetry, as in this example:

public void ConfigureServices(IServiceCollection services)
{
    Microsoft.ApplicationInsights.AspNetCore.Extensions.ApplicationInsightsServiceOptions aiOptions
                = new Microsoft.ApplicationInsights.AspNetCore.Extensions.ApplicationInsightsServiceOptions();
    // Disables adaptive sampling.
    aiOptions.EnableAdaptiveSampling = false;

    // Disables QuickPulse (Live Metrics stream).
    aiOptions.EnableQuickPulseMetricStream = false;
    services.AddApplicationInsightsTelemetry(aiOptions);
}

This table has the full list of ApplicationInsightsServiceOptions settings:

Setting Description Default
EnablePerformanceCounterCollectionModule Enable/Disable PerformanceCounterCollectionModule true
EnableRequestTrackingTelemetryModule Enable/Disable RequestTrackingTelemetryModule true
EnableEventCounterCollectionModule Enable/Disable EventCounterCollectionModule true
EnableDependencyTrackingTelemetryModule Enable/Disable DependencyTrackingTelemetryModule true
EnableAppServicesHeartbeatTelemetryModule Enable/Disable AppServicesHeartbeatTelemetryModule true
EnableAzureInstanceMetadataTelemetryModule Enable/Disable AzureInstanceMetadataTelemetryModule true
EnableQuickPulseMetricStream Enable/Disable LiveMetrics feature true
EnableAdaptiveSampling Enable/Disable Adaptive Sampling true
EnableHeartbeat Enable/Disable Heartbeats feature, which periodically (15-min default) sends a custom metric named 'HeartbeatState' with information about the runtime like .NET Version, Azure Environment information, if applicable, etc. true
AddAutoCollectedMetricExtractor Enable/Disable AutoCollectedMetrics extractor, which is a TelemetryProcessor that sends pre-aggregated metrics about Requests/Dependencies before sampling takes place. true
RequestCollectionOptions.TrackExceptions Enable/Disable reporting of unhandled Exception tracking by the Request collection module. false in NETSTANDARD2.0 (because Exceptions are tracked with ApplicationInsightsLoggerProvider), true otherwise.
EnableDiagnosticsTelemetryModule Enable/Disable DiagnosticsTelemetryModule. Disabling this will cause the following settings to be ignored; EnableHeartbeat, EnableAzureInstanceMetadataTelemetryModule, EnableAppServicesHeartbeatTelemetryModule true

For the most current list, see the configurable settings in ApplicationInsightsServiceOptions.

Configuration recommendation for Microsoft.ApplicationInsights.AspNetCore SDK 2.15.0 and later

In Microsoft.ApplicationInsights.AspNetCore SDK version 2.15.0 and later, we recommend configuring every setting available in ApplicationInsightsServiceOptions, including InstrumentationKey using the application's IConfiguration instance. The settings must be under the section "ApplicationInsights", as shown in the following example. The following section from appsettings.json configures the instrumentation key and disables adaptive sampling and performance counter collection.

{
    "ApplicationInsights": {
    "InstrumentationKey": "putinstrumentationkeyhere",
    "EnableAdaptiveSampling": false,
    "EnablePerformanceCounterCollectionModule": false
    }
}

If services.AddApplicationInsightsTelemetry(aiOptions) is used, it overrides the settings from Microsoft.Extensions.Configuration.IConfiguration.

Sampling

The Application Insights SDK for ASP.NET Core supports both fixed-rate and adaptive sampling. By default, adaptive sampling is enabled.

For more information, see Configure adaptive sampling for ASP.NET Core applications.

Adding TelemetryInitializers

When you want to enrich telemetry with additional information, use telemetry initializers.

Add any new TelemetryInitializer to the DependencyInjection container as shown in the following code. The SDK automatically picks up any TelemetryInitializer that's added to the DependencyInjection container.

public void ConfigureServices(IServiceCollection services)
{
    services.AddSingleton<ITelemetryInitializer, MyCustomTelemetryInitializer>();
}

Note

services.AddSingleton<ITelemetryInitializer, MyCustomTelemetryInitializer>(); works for simple initializers. For others, the following is required: services.AddSingleton(new MyCustomTelemetryInitializer() { fieldName = "myfieldName" });

Removing TelemetryInitializers

By default, telemetry initializers are present. To remove all or specific telemetry initializers, use the following sample code after you call AddApplicationInsightsTelemetry().

public void ConfigureServices(IServiceCollection services)
{
    services.AddApplicationInsightsTelemetry();

    // Remove a specific built-in telemetry initializer
    var tiToRemove = services.FirstOrDefault<ServiceDescriptor>
                        (t => t.ImplementationType == typeof(AspNetCoreEnvironmentTelemetryInitializer));
    if (tiToRemove != null)
    {
        services.Remove(tiToRemove);
    }

    // Remove all initializers
    // This requires importing namespace by using Microsoft.Extensions.DependencyInjection.Extensions;
    services.RemoveAll(typeof(ITelemetryInitializer));
}

Adding telemetry processors

You can add custom telemetry processors to TelemetryConfiguration by using the extension method AddApplicationInsightsTelemetryProcessor on IServiceCollection. You use telemetry processors in advanced filtering scenarios. Use the following example.

public void ConfigureServices(IServiceCollection services)
{
    // ...
    services.AddApplicationInsightsTelemetry();
    services.AddApplicationInsightsTelemetryProcessor<MyFirstCustomTelemetryProcessor>();

    // If you have more processors:
    services.AddApplicationInsightsTelemetryProcessor<MySecondCustomTelemetryProcessor>();
}

Configuring or removing default TelemetryModules

Application Insights uses telemetry modules to automatically collect useful telemetry about specific workloads without requiring manual tracking by user.

By default, the following automatic-collection modules are enabled. These modules are responsible for automatically collecting telemetry. You can disable or configure them to alter their default behavior.

  • RequestTrackingTelemetryModule - Collects RequestTelemetry from incoming web requests
  • DependencyTrackingTelemetryModule - Collects DependencyTelemetry from outgoing http calls and sql calls
  • PerformanceCollectorModule - Collects Windows PerformanceCounters
  • QuickPulseTelemetryModule - Collects telemetry for showing in Live Metrics portal
  • AppServicesHeartbeatTelemetryModule - Collects heart beats (which are sent as custom metrics), about Azure App Service environment where application is hosted
  • AzureInstanceMetadataTelemetryModule - Collects heart beats (which are sent as custom metrics), about Azure VM environment where application is hosted
  • EventCounterCollectionModule - Collects EventCounters; this module is a new feature and is available in SDK version 2.8.0 and later

To configure any default TelemetryModule, use the extension method ConfigureTelemetryModule<T> on IServiceCollection, as shown in the following example.

using Microsoft.ApplicationInsights.DependencyCollector;
using Microsoft.ApplicationInsights.Extensibility.PerfCounterCollector;

public void ConfigureServices(IServiceCollection services)
{
    services.AddApplicationInsightsTelemetry();

    // The following configures DependencyTrackingTelemetryModule.
    // Similarly, any other default modules can be configured.
    services.ConfigureTelemetryModule<DependencyTrackingTelemetryModule>((module, o) =>
            {
                module.EnableW3CHeadersInjection = true;
            });

    // The following removes all default counters from EventCounterCollectionModule, and adds a single one.
    services.ConfigureTelemetryModule<EventCounterCollectionModule>(
            (module, o) =>
            {
                module.Counters.Add(new EventCounterCollectionRequest("System.Runtime", "gen-0-size"));
            }
        );

    // The following removes PerformanceCollectorModule to disable perf-counter collection.
    // Similarly, any other default modules can be removed.
    var performanceCounterService = services.FirstOrDefault<ServiceDescriptor>(t => t.ImplementationType == typeof(PerformanceCollectorModule));
    if (performanceCounterService != null)
    {
        services.Remove(performanceCounterService);
    }
}

In versions 2.12.2 and later, ApplicationInsightsServiceOptions includes an easy option to disable any of the default modules.

Configuring a telemetry channel

The default telemetry channel is ServerTelemetryChannel. The following example shows how to override it.

using Microsoft.ApplicationInsights.Channel;

    public void ConfigureServices(IServiceCollection services)
    {
        // Use the following to replace the default channel with InMemoryChannel.
        // This can also be applied to ServerTelemetryChannel.
        services.AddSingleton(typeof(ITelemetryChannel), new InMemoryChannel() {MaxTelemetryBufferCapacity = 19898 });

        services.AddApplicationInsightsTelemetry();
    }

Disable telemetry dynamically

If you want to disable telemetry conditionally and dynamically, you can resolve the TelemetryConfiguration instance with an ASP.NET Core dependency injection container anywhere in your code and set the DisableTelemetry flag on it.

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddApplicationInsightsTelemetry();
    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env, TelemetryConfiguration configuration)
    {
        configuration.DisableTelemetry = true;
        ...
    }

The preceding code sample prevents the sending of telemetry to Application Insights. It doesn't prevent any automatic collection modules from collecting telemetry. If you want to remove a particular auto collection module, see remove the telemetry module.

Frequently asked questions

Does Application Insights support ASP.NET Core 3.X?

Yes. Update to Application Insights SDK for ASP.NET Core version 2.8.0 or later. Earlier versions of the SDK don't support ASP.NET Core 3.X.

Also, if you're enabling server-side telemetry based on Visual Studio, update to the latest version of Visual Studio 2019 (16.3.0) to onboard. Earlier versions of Visual Studio don't support automatic onboarding for ASP.NET Core 3.X apps.

How can I track telemetry that's not automatically collected?

Get an instance of TelemetryClient by using constructor injection, and call the required TrackXXX() method on it. We don't recommend creating new TelemetryClient or TelemetryConfiguration instances in an ASP.NET Core application. A singleton instance of TelemetryClient is already registered in the DependencyInjection container, which shares TelemetryConfiguration with rest of the telemetry. Creating a new TelemetryClient instance is recommended only if it needs a configuration that's separate from the rest of the telemetry.

The following example shows how to track additional telemetry from a controller.

using Microsoft.ApplicationInsights;

public class HomeController : Controller
{
    private TelemetryClient telemetry;

    // Use constructor injection to get a TelemetryClient instance.
    public HomeController(TelemetryClient telemetry)
    {
        this.telemetry = telemetry;
    }

    public IActionResult Index()
    {
        // Call the required TrackXXX method.
        this.telemetry.TrackEvent("HomePageRequested");
        return View();
    }

For more information about custom data reporting in Application Insights, see Application Insights custom metrics API reference. A similar approach can be used for sending custom metrics to Application Insights using the GetMetric API.

How do I customize ILogger logs collection?

By default, only Warning logs and more severe logs are automatically captured. To change this behavior, explicitly override the logging configuration for the provider ApplicationInsights as shown below. The following configuration allows ApplicationInsights to capture all Information logs and more severe logs.

{
  "Logging": {
    "LogLevel": {
      "Default": "Warning"
    },
    "ApplicationInsights": {
      "LogLevel": {
        "Default": "Information"
      }
    }
  }
}

It's important to note that the following doesn't cause the ApplicationInsights provider to capture Information logs. It doesn't capture it because the SDK adds a default logging filter that instructs ApplicationInsights to capture only Warning logs and more severe logs. ApplicationInsights requires an explicit override.

{
  "Logging": {
    "LogLevel": {
      "Default": "Information"
    }
  }
}

For more information, see ILogger configuration.

Some Visual Studio templates used the UseApplicationInsights() extension method on IWebHostBuilder to enable Application Insights. Is this usage still valid?

The extension method UseApplicationInsights() is still supported, but it's marked as obsolete in Application Insights SDK version 2.8.0 and later. It will be removed in the next major version of the SDK. To enable Application Insights telemetry, we recommend using AddApplicationInsightsTelemetry() because it provides overloads to control some configuration. Also, in ASP.NET Core 3.X apps, services.AddApplicationInsightsTelemetry() is the only way to enable Application Insights.

I'm deploying my ASP.NET Core application to Web Apps. Should I still enable the Application Insights extension from Web Apps?

If the SDK is installed at build time as shown in this article, you don't need to enable the Application Insights extension from the App Service portal. Even if the extension is installed, it will back off when it detects that the SDK is already added to the application. If you enable Application Insights from the extension, you don't have to install and update the SDK. But if you enable Application Insights by following instructions in this article, you have more flexibility because:

  • Application Insights telemetry will continue to work in:
    • All operating systems, including Windows, Linux, and Mac.
    • All publish modes, including self-contained or framework dependent.
    • All target frameworks, including the full .NET Framework.
    • All hosting options, including Web Apps, VMs, Linux, containers, Azure Kubernetes Service, and non-Azure hosting.
    • All .NET Core versions including preview versions.
  • You can see telemetry locally when you're debugging from Visual Studio.
  • You can track additional custom telemetry by using the TrackXXX() API.
  • You have full control over the configuration.

Can I enable Application Insights monitoring by using tools like Azure Monitor Application Insights Agent (formerly Status Monitor v2)?

Yes. Starting from Application Insights Agent 2.0.0-beta1, ASP.NET Core applications hosted in IIS are supported.

If I run my application in Linux, are all features supported?

Yes. Feature support for the SDK is the same in all platforms, with the following exceptions:

  • The SDK collects Event Counters on Linux because Performance Counters are only supported in Windows. Most metrics are the same.
  • Although ServerTelemetryChannel is enabled by default, if the application is running in Linux or macOS, the channel doesn't automatically create a local storage folder to keep telemetry temporarily if there are network issues. Because of this limitation, telemetry is lost when there are temporary network or server issues. To work around this issue, configure a local folder for the channel:
using Microsoft.ApplicationInsights.Channel;
using Microsoft.ApplicationInsights.WindowsServer.TelemetryChannel;

    public void ConfigureServices(IServiceCollection services)
    {
        // The following will configure the channel to use the given folder to temporarily
        // store telemetry items during network or Application Insights server issues.
        // User should ensure that the given folder already exists
        // and that the application has read/write permissions.
        services.AddSingleton(typeof(ITelemetryChannel),
                                new ServerTelemetryChannel () {StorageFolder = "/tmp/myfolder"});
        services.AddApplicationInsightsTelemetry();
    }

This limitation is not applicable from version 2.15.0 and later.

Is this SDK supported for the new .NET Core 3.X Worker Service template applications?

This SDK requires HttpContext; therefore, it doesn't work in any non-HTTP applications, including the .NET Core 3.X Worker Service applications. To enable Application Insights in such applications using the newly released Microsoft.ApplicationInsights.WorkerService SDK, see Application Insights for Worker Service applications (non-HTTP applications).

Open-source SDK

For the latest updates and bug fixes, see the release notes.

Next steps