Open Telemetry 001

Metric-Duration.cs

using OpenTelemetry.Metrics;
using OpenTelemetry.Trace;

using System.Diagnostics;
using System.Diagnostics.Metrics;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddScoped<EndpointMeters>();
builder.Services.AddOpenTelemetry()
    .WithMetrics(options =>
    {
        options.AddMeter(EndpointMeters.Meter.Name);
        options.AddConsoleExporter();
    });

var app = builder.Build();
app.UseHttpsRedirection();
app.MapGet("/api1", GetData).WithName("GetApi1");
app.Run();

async Task<string> GetData(HttpContext context, EndpointMeters metrics)
{
    var endpointTags = context.GetEndpointTags();

    metrics.Requests.Add(1, endpointTags);

    using (DurationMetric.Measure(metrics.Duration, endpointTags))
    {
        await Task.Delay(Random.Shared.Next(100, 1000));
        return DateTime.Now.ToString();
    }
}

public class EndpointMeters
{
    public static readonly Meter Meter = new(nameof(EndpointMeters), "0.0.1");

    public readonly Counter<int> Requests
        = Meter.CreateCounter<int>("requests", description: "Number of requests");

    public readonly Histogram<double> Duration
        = Meter.CreateHistogram<double>("request_duration", "ms", description: "Duration in milliseconds");
}

public class DurationMetric(Histogram<double> metric, TagList endpointTags) : IDisposable
{
    public static DurationMetric Measure(Histogram<double> metric, TagList endpointTags) => new(metric, endpointTags);

    private readonly Stopwatch stopwatch = Stopwatch.StartNew();

    public void Dispose() => metric.Record(stopwatch.Elapsed.TotalMilliseconds, endpointTags);
}

public static class Extensions
{
    public static TagList GetEndpointTags(this HttpContext context)
    {
        return [new("endpoint", context.GetEndpointName())];
    }

    public static string GetEndpointName(this HttpContext context)
    {
        var endpoint = context.GetEndpoint() as RouteEndpoint;
        var endpointNameMetadata = endpoint?.Metadata.GetMetadata<EndpointNameMetadata>();
        return endpointNameMetadata?.EndpointName ?? "unknown";
    }
}

Metric.cs

using OpenTelemetry.Metrics;
using OpenTelemetry.Trace;

using System.Diagnostics.Metrics;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddScoped<EndpointMeters>();
builder.Services.AddOpenTelemetry()
    .WithMetrics(options =>
    {
        options.AddMeter(EndpointMeters.Meter.Name);
        options.AddConsoleExporter();
    });


var app = builder.Build();
app.UseHttpsRedirection();
app.MapGet("/api1", GetData).WithName("GetApi1");
app.Run();

async Task<string> GetData(EndpointMeters metrics)
{
    metrics.Requests.Add(1);
    return DateTime.Now.ToString();
}

public class EndpointMeters
{
    public static readonly Meter Meter = new("Endpoint.Meters", "0.0.1");
    public readonly Counter<int> Requests = Meter.CreateCounter<int>("requests", description: "Number of requests");
}

Trace.cs

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

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddOpenTelemetry()
    .WithTracing(options =>
    {
        options.SetResourceBuilder(ResourceBuilder.CreateDefault().AddService("TelemetryDemo"));
        options.SetSampler(new AlwaysOnSampler());
        options.AddConsoleExporter(exporterOptions =>
        {
            exporterOptions.Targets = OpenTelemetry.Exporter.ConsoleExporterOutputTargets.Console;
        });
    });

var app = builder.Build();
app.UseHttpsRedirection();
app.MapGet("/api1", GetData).WithName("GetApi1");
app.Run();

async Task<string> GetData(HttpContext context, TracerProvider tracerProvider)
{
    var tracer = tracerProvider.GetTracer("EndpointTracer");
    using (var span = tracer.StartActiveSpan("ProcessData"))
    {
        span.SetAttribute("endpoint", context.GetEndpointName());
        await Task.Delay(Random.Shared.Next(100, 1000));
        span.AddEvent("Processing complete");
        return DateTime.Now.ToString();
    }
}

public static class Extensions
{
    public static string GetEndpointName(this HttpContext context)
    {
        var endpoint = context.GetEndpoint() as RouteEndpoint;
        var endpointNameMetadata = endpoint?.Metadata.GetMetadata<EndpointNameMetadata>();
        return endpointNameMetadata?.EndpointName ?? "unknown";
    }
}