Name: kopai/otel-instrumentation
Rating: 1 (1 reviews)
Author: kopai

kopai/otel-instrumentation

Instrument applications with OpenTelemetry SDK and validate telemetry using Kopai. Use when setting up observability, adding tracing/logging/metrics, testing instrumentation, debugging missing telemetry data, or when traces/logs/metrics aren't appearing after setup. Also use when users say things like "my traces aren't showing up", "I don't see any data", or "how do I add observability to my app".

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title	impact	tags
.NET Instrumentation	HIGH	lang, dotnet, csharp, traces, logs, metrics

.NET Instrumentation

Impact: HIGH

Set up OpenTelemetry SDK for .NET applications with traces, logs, and metrics.

Install

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

Configuration

CRITICAL: The OTLP exporter defaults to gRPC. For HTTP endpoints (port 4318), you MUST set OtlpExportProtocol.HttpProtobuf and append signal paths.

using OpenTelemetry.Exporter;

// Get endpoint from environment
var endpoint = Environment.GetEnvironmentVariable("OTEL_EXPORTER_OTLP_ENDPOINT")
    ?? "http://localhost:4318";
var serviceName = Environment.GetEnvironmentVariable("OTEL_SERVICE_NAME")
    ?? "my-service";

Environment Variables:

Variable	Description
`OTEL_EXPORTER_OTLP_ENDPOINT`	OTLP endpoint (e.g., `http://localhost:4318`)
`OTEL_SERVICE_NAME`	Service name shown in observability backend

Traces

builder.Services.AddOpenTelemetry()
    .ConfigureResource(r => r.AddService(serviceName))
    .WithTracing(tracing => tracing
        .AddAspNetCoreInstrumentation()
        .AddOtlpExporter(opts =>
        {
            opts.Endpoint = new Uri($"{endpoint}/v1/traces");
            opts.Protocol = OtlpExportProtocol.HttpProtobuf;
        }));

Logs

using OpenTelemetry.Resources;

var resourceBuilder = ResourceBuilder.CreateDefault()
    .AddService(serviceName);

builder.Logging.AddOpenTelemetry(logging =>
{
    logging.SetResourceBuilder(resourceBuilder);
    logging.AddOtlpExporter(opts =>
    {
        opts.Endpoint = new Uri($"{endpoint}/v1/logs");
        opts.Protocol = OtlpExportProtocol.HttpProtobuf;
    });
});

Metrics

using System.Diagnostics.Metrics;

var meter = new Meter(serviceName);
var requestCounter = meter.CreateCounter<long>("requests", "1", "Request count");

builder.Services.AddOpenTelemetry()
    .WithMetrics(metrics => metrics
        .AddAspNetCoreInstrumentation()
        .AddMeter(serviceName)
        .AddOtlpExporter(opts =>
        {
            opts.Endpoint = new Uri($"{endpoint}/v1/metrics");
            opts.Protocol = OtlpExportProtocol.HttpProtobuf;
        }));

Complete Example

using System.Diagnostics.Metrics;
using OpenTelemetry.Exporter;
using OpenTelemetry.Logs;
using OpenTelemetry.Metrics;
using OpenTelemetry.Resources;
using OpenTelemetry.Trace;

var builder = WebApplication.CreateBuilder(args);

var endpoint = Environment.GetEnvironmentVariable("OTEL_EXPORTER_OTLP_ENDPOINT")
    ?? "http://localhost:4318";
var serviceName = Environment.GetEnvironmentVariable("OTEL_SERVICE_NAME")
    ?? "my-service";

var meter = new Meter(serviceName);
var requestCounter = meter.CreateCounter<long>("requests");

var resourceBuilder = ResourceBuilder.CreateDefault().AddService(serviceName);

// Traces and Metrics
builder.Services.AddOpenTelemetry()
    .ConfigureResource(r => r.AddService(serviceName))
    .WithTracing(tracing => tracing
        .AddAspNetCoreInstrumentation()
        .AddOtlpExporter(opts =>
        {
            opts.Endpoint = new Uri($"{endpoint}/v1/traces");
            opts.Protocol = OtlpExportProtocol.HttpProtobuf;
        }))
    .WithMetrics(metrics => metrics
        .AddAspNetCoreInstrumentation()
        .AddMeter(serviceName)
        .AddOtlpExporter(opts =>
        {
            opts.Endpoint = new Uri($"{endpoint}/v1/metrics");
            opts.Protocol = OtlpExportProtocol.HttpProtobuf;
        }));

// Logs
builder.Logging.AddOpenTelemetry(logging =>
{
    logging.SetResourceBuilder(resourceBuilder);
    logging.AddOtlpExporter(opts =>
    {
        opts.Endpoint = new Uri($"{endpoint}/v1/logs");
        opts.Protocol = OtlpExportProtocol.HttpProtobuf;
    });
});

var app = builder.Build();
app.MapGet("/hello", (ILogger<Program> logger) =>
{
    requestCounter.Add(1);
    logger.LogInformation("Hello endpoint called");
    return Results.Json(new { message = "Hello!" });
});
app.Run();

Reference

OpenTelemetry .NET