README.md

Grpc.Net.Client Instrumentation for OpenTelemetry

This is an Instrumentation Library which instruments Grpc.Net.Client and collects telemetry about outgoing gRPC requests.

Supported .NET Versions

This package targets NETSTANDARD2.1 and hence can be used in any .NET versions implementing NETSTANDARD2.1.

Steps to enable OpenTelemetry.Instrumentation.GrpcNetClient

Step 1: Install Package

Add a reference to the OpenTelemetry.Instrumentation.GrpcNetClient package. Also, add any other instrumentations & exporters you will need.

dotnet add package OpenTelemetry.Instrumentation.GrpcNetClient

Step 2: Enable Grpc.Net.Client Instrumentation at application startup

Grpc.Net.Client instrumentation must be enabled at application startup.

The following example demonstrates adding Grpc.Net.Client instrumentation to a console application. This example also sets up the OpenTelemetry Console exporter and adds instrumentation for HttpClient, which requires adding the packages OpenTelemetry.Exporter.Console and OpenTelemetry.Instrumentation.Http to the application. As Grpc.Net.Client uses HttpClient underneath, it is recommended to enable HttpClient instrumentation as well to ensure proper context propagation. This would cause an activity being produced for both a gRPC call and its underlying HTTP call. This behavior can be configured.

using OpenTelemetry.Trace;

public class Program
{
    public static void Main(string[] args)
    {
        using var tracerProvider = Sdk.CreateTracerProviderBuilder()
            .AddGrpcClientInstrumentation()
            .AddHttpClientInstrumentation()
            .AddConsoleExporter()
            .Build();
    }
}

For an ASP.NET Core application, adding instrumentation is typically done in the ConfigureServices of your Startup class. Refer to documentation for OpenTelemetry.Instrumentation.AspNetCore.

Advanced configuration

This instrumentation can be configured to change the default behavior by using GrpcClientInstrumentationOptions.

SuppressDownstreamInstrumentation

This option prevents downstream instrumentation from being invoked. Grpc.Net.Client is built on top of HttpClient. When instrumentation for both libraries is enabled, SuppressDownstreamInstrumentation prevents the HttpClient instrumentation from generating an additional activity. Additionally, since HttpClient instrumentation is normally responsible for propagating context (ActivityContext and Baggage), Grpc.Net.Client instrumentation propagates context when SuppressDownstreamInstrumentation is enabled.

The following example shows how to use SuppressDownstreamInstrumentation.

using var tracerProvider = Sdk.CreateTracerProviderBuilder()
    .AddGrpcClientInstrumentation(
        opt => opt.SuppressDownstreamInstrumentation = true)
    .AddHttpClientInstrumentation()
    .Build();

Enrich

This option allows one to enrich the activity with additional information from the raw HttpRequestMessage object. The Enrich action is called only when activity.IsAllDataRequested is true. It contains the activity itself (which can be enriched), the name of the event, and the actual raw object. For event name "OnStartActivity", the actual object will be HttpRequestMessage.

The following code snippet shows how to add additional tags using Enrich.

services.AddOpenTelemetryTracing((builder) =>
{
    builder
    .AddGrpcClientInstrumentation(opt => opt.Enrich
        = (activity, eventName, rawObject) =>
    {
        if (eventName.Equals("OnStartActivity"))
        {
            if (rawObject is HttpRequestMessage request)
            {
                activity.SetTag("requestVersion", request.Version);
            }
        }
    })
});

Processor, is the general extensibility point to add additional properties to any activity. The Enrich option is specific to this instrumentation, and is provided to get access to HttpRequest and HttpResponse.

References

• gRPC for .NET
• OpenTelemetry Project