aspnetcore-webapi

Enable Azure Monitor Profiler for an ASP.NET Core WebAPI

This is an example app to enable Azure Monitor Profiler in ASP.NET Core WebAPI with Azure Monitor OpenTelemetry distro.

Using Application Insights ASP.NET Core 3.x instead? See the aspnetcore-aisdk3 example.

Here are the steps to build this example step to step.

Create an application

Run this command to create a web api application:

dotnet new web -n SimpleApp -o . -f net8.0

Add reference to NuGet packages

Add the following 2 packages, refer to SimpleApp.csproj for details:

<ItemGroup>
    <PackageReference Include="Azure.Monitor.OpenTelemetry.AspNetCore" Version="[1.*-*, 2.0.0)" />
    <PackageReference Include="Azure.Monitor.OpenTelemetry.Profiler" Version="[1.*-*, 2.0.0)" />
</ItemGroup>

Restore the packages:

> dotnet restore SimpleApp.csproj

Optionally, check the resolved package version

> dotnet list package
Project 'SimpleApp' has the following package references
   [net8.0]:
   Top-level Package                                Requested        Resolved
   > Azure.Monitor.OpenTelemetry.AspNetCore         [1.*-*, 2.0.0)   1.3.0-beta.2
   > Azure.Monitor.OpenTelemetry.Profiler           [1.*-*, 2.0.0)   1.0.0-beta1
   > Microsoft.VisualStudioEng.MicroBuild.Core      1.0.0            1.0.0

Update the code to enable the profiler

Refer to Program.cs for more details:

builder.Services.AddOpenTelemetry()
    .UseAzureMonitor()          // Enable Azure Monitor OpenTelemetry distro for ASP.NET Core
    .AddAzureMonitorProfiler(); // Add Azure Monitor Profiler

If you run the code now, an exception will throw:

Unhandled exception. System.InvalidOperationException: A connection string was not found. Please set your connection string.

Set up the connection string

Refer to connection string section to see options. Here's a quick way for local test using environment variable in PowerShell:

$env:APPLICATIONINSIGHTS_CONNECTION_STRING="InstrumentationKey=5d..."

Tips: Copy the connection string from the overview blade of the application insights resource.

Bake in some delay for your operation, for example

app.MapGet("/", async () =>
{
    await Task.Delay(2000); // 2 seconds delay
    return "Hello World!";
});

⚠️ Trace analysis might fail if the operation is too fast, like finished within 10 milliseconds.

Run your application

dotnet run

Generate some traffic for profiler to capture the issue:

curl http://localhost:5082