opentelemetry-dotnet-instrumentation/docs/iis-instrumentation.md

Instrument an ASP.NET application deployed on IIS

Set environment variables

You can add the <environmentVariables> in applicationHost.config to set environment variables for given application pools.

For IIS versions older than 10.0, you can consider creating a distinct user, set its environment variables and use it as the application pool user.

For ASP.NET Core application you can also use the <environmentVariable> elements inside the <aspNetCore> block of your Web.config file to set environment variables.

You can consider setting common environment variables, such us COR_PROFILER, for all application deployed to IIS by setting the environment variables for W3SVC and WAS Windows Services as described in windows-service-instrumentation.md.

Add TelemetryHttpModule ASP.NET HTTP module

This is NOT required for ASP.NET Core deployments.

This step is necessary only for ASP.NET (.NET Framework).

Add OpenTelemetry.Instrumentation.AspNet.TelemetryHttpModule, OpenTelemetry.Instrumentation.AspNet.TelemetryHttpModule ASP.NET HTTP module to your application's Web.config. You can add it in the following places:

  <system.web>
    <httpModules>
      <add name="TelemetryHttpModule" type="OpenTelemetry.Instrumentation.AspNet.TelemetryHttpModule, OpenTelemetry.Instrumentation.AspNet.TelemetryHttpModule" />
    </httpModules>
  </system.web>

  <system.webServer>
    <validation validateIntegratedModeConfiguration="false" />
    <modules>
      <remove name="TelemetryHttpModule" />
      <add name="TelemetryHttpModule" type="OpenTelemetry.Instrumentation.AspNet.TelemetryHttpModule, OpenTelemetry.Instrumentation.AspNet.TelemetryHttpModule" preCondition="managedHandler" />
    </modules>
  </system.webServer>

The ASP.NET HTTP module can be also set in applicationHost.config. Here is an example where you can add the module to set it for all ASP.NET application running in Integrated Pipeline Mode:

  <location path="" overrideMode="Allow">
    <system.webServer>
      <modules>
        <add name="TelemetryHttpModule" type="OpenTelemetry.Instrumentation.AspNet.TelemetryHttpModule, OpenTelemetry.Instrumentation.AspNet.TelemetryHttpModule" preCondition="managedHandler" />
      </modules>
    </system.webServer>
  </location>

Enable ASP.NET instrumentation

Make sure to enable the ASP.NET instrumentation by setting OTEL_DOTNET_AUTO_TRACES_ENABLED_INSTRUMENTATIONS=AspNet.