.NET - Rocketgraph

Two routes. Automatic instrumentation needs no code changes and suits an app you would rather not rebuild. The SDK route is a few lines in Program.cs and gives finer control. Both send the same OTLP data.

Option A — automatic, no code changes

curl -sSfL https://github.com/open-telemetry/opentelemetry-dotnet-instrumentation/releases/latest/download/otel-dotnet-auto-install.sh -O
sh ./otel-dotnet-auto-install.sh

# Source it — do not execute it, or the profiler variables are lost.
. $HOME/.otel-dotnet-auto/instrument.sh

export OTEL_SERVICE_NAME="my-dotnet-service"
export OTEL_EXPORTER_OTLP_ENDPOINT="https://ingress.rocketlog.io"
export OTEL_EXPORTER_OTLP_HEADERS="Authorization=Bearer rg_live_xxxxxx"
export OTEL_EXPORTER_OTLP_PROTOCOL="http/protobuf"

dotnet run

Option B — the SDK

dotnet add package OpenTelemetry.Extensions.Hosting
dotnet add package OpenTelemetry.Exporter.OpenTelemetryProtocol
dotnet add package OpenTelemetry.Instrumentation.AspNetCore
dotnet add package OpenTelemetry.Instrumentation.Http

using OpenTelemetry.Logs;
using OpenTelemetry.Metrics;
using OpenTelemetry.Resources;
using OpenTelemetry.Trace;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddOpenTelemetry()
    .ConfigureResource(r => r.AddService("my-dotnet-service"))
    .WithTracing(t => t
        .AddAspNetCoreInstrumentation()
        .AddHttpClientInstrumentation()
        .AddOtlpExporter())
    .WithMetrics(m => m
        .AddAspNetCoreInstrumentation()
        .AddRuntimeInstrumentation()
        .AddOtlpExporter());

builder.Logging.AddOpenTelemetry(o =>
{
    o.IncludeFormattedMessage = true;
    o.IncludeScopes = true;
    o.AddOtlpExporter();
});

var app = builder.Build();

AddOtlpExporter() with no arguments reads OTEL_EXPORTER_OTLP_ENDPOINT, _HEADERS and _PROTOCOL from the environment, so the same build works in every deployment.

Custom spans

using System.Diagnostics;

private static readonly ActivitySource Activity = new("Payments");

using var activity = Activity.StartActivity("settle-transfer");
activity?.SetTag("transfer.id", transferId);

try
{
    await SettleAsync(transferId);
}
catch (Exception ex)
{
    activity?.SetStatus(ActivityStatusCode.Error, ex.Message);
    activity?.AddException(ex);
    throw;
}

.NET uses System.Diagnostics.Activity as its span type. An ActivitySource whose name is not registered with AddSource() produces null activities and no data — the usual reason custom spans go missing.