ServiceDefaults.cs

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Diagnostics.HealthChecks;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Diagnostics.HealthChecks;
using Microsoft.Extensions.Logging;
using OpenTelemetry;
using OpenTelemetry.Metrics;
using OpenTelemetry.Trace;
using Serilog;
using Serilog.Events;
using Serilog.Sinks.OpenTelemetry;

namespace Microsoft.Extensions.Hosting;

// Adds common .NET Aspire services: service discovery, resilience, health checks, and OpenTelemetry.
// This project should be referenced by each service project in your solution.
// To learn more about using this project, see https://aka.ms/dotnet/aspire/service-defaults
public static class Extensions
{
    public static TBuilder AddServiceDefaults<TBuilder>(this TBuilder builder) where TBuilder : IHostApplicationBuilder
    {
        builder.ConfigureLogging();

        builder.ConfigureOpenTelemetry();

        builder.AddDefaultHealthChecks();

        builder.Services.AddServiceDiscovery();

        builder.Services.ConfigureHttpClientDefaults(http =>
        {
            // Turn on resilience by default
            http.AddStandardResilienceHandler();

            // Turn on service discovery by default
            http.AddServiceDiscovery();
        });

        // Uncomment the following to restrict the allowed schemes for service discovery.
        // builder.Services.Configure<ServiceDiscoveryOptions>(options =>
        // {
        //     options.AllowedSchemes = ["https"];
        // });

        return builder;
    }

    public static TBuilder ConfigureLogging<TBuilder>(this TBuilder builder) where TBuilder : IHostApplicationBuilder
    {
        // Create Serilog logger configuration
        var loggerConfiguration = new LoggerConfiguration()
            .MinimumLevel.Information()
            .MinimumLevel.Override("Microsoft", LogEventLevel.Warning)
            .MinimumLevel.Override("System", LogEventLevel.Warning)
            .Enrich.FromLogContext()
            .Enrich.WithProperty("Application", builder.Environment.ApplicationName)
            .WriteTo.Console()
            .WriteTo.Seq(builder.Configuration.GetConnectionString("seq") ?? throw new InvalidOperationException("Connection for Seq cannot be found"))
            .WriteTo.OpenTelemetry(options =>
                {
                    options.Endpoint = builder.Configuration["OTEL_EXPORTER_OTLP_ENDPOINT"];
                    options.Protocol = OtlpProtocol.HttpProtobuf;
                    options.ResourceAttributes = new Dictionary<string, object>
                    {
                        ["service.name"] = builder.Environment.ApplicationName
                    };
                });

        // Create the Serilog logger
        Log.Logger = loggerConfiguration.CreateLogger();

        // Use Serilog for all logging
        builder.Logging.ClearProviders();
        builder.Logging.Services.AddSerilog(Log.Logger, dispose: true);

        // Configure OpenTelemetry to use Serilog
        return builder;
    }

    public static TBuilder ConfigureOpenTelemetry<TBuilder>(this TBuilder builder) where TBuilder : IHostApplicationBuilder
    {
        builder.Logging.AddOpenTelemetry(logging =>
        {
            logging.IncludeFormattedMessage = true;
            logging.IncludeScopes = true;
        });

        builder.Services.AddOpenTelemetry()
            .WithMetrics(metrics =>
            {
                metrics.AddAspNetCoreInstrumentation()
                    .AddHttpClientInstrumentation()
                    .AddRuntimeInstrumentation();
            })
            .WithTracing(tracing =>
            {
                tracing.AddSource(builder.Environment.ApplicationName)
                    .AddAspNetCoreInstrumentation()
                    // Uncomment the following line to enable gRPC instrumentation (requires the OpenTelemetry.Instrumentation.GrpcNetClient package)
                    //.AddGrpcClientInstrumentation()
                    .AddHttpClientInstrumentation();
            });

        builder.AddOpenTelemetryExporters();

        return builder;
    }

    private static TBuilder AddOpenTelemetryExporters<TBuilder>(this TBuilder builder) where TBuilder : IHostApplicationBuilder
    {
        var useOtlpExporter = !string.IsNullOrWhiteSpace(builder.Configuration["OTEL_EXPORTER_OTLP_ENDPOINT"]);

        if (useOtlpExporter)
        {
            builder.Services.AddOpenTelemetry().UseOtlpExporter();
        }

        // Uncomment the following lines to enable the Azure Monitor exporter (requires the Azure.Monitor.OpenTelemetry.AspNetCore package)
        //if (!string.IsNullOrEmpty(builder.Configuration["APPLICATIONINSIGHTS_CONNECTION_STRING"]))
        //{
        //    builder.Services.AddOpenTelemetry()
        //       .UseAzureMonitor();
        //}

        return builder;
    }

    public static TBuilder AddDefaultHealthChecks<TBuilder>(this TBuilder builder) where TBuilder : IHostApplicationBuilder
    {
        builder.Services.AddHealthChecks()
            // Add a default liveness check to ensure app is responsive
            .AddCheck("self", () => HealthCheckResult.Healthy(), ["live"]);

        return builder;
    }

    public static WebApplication MapDefaultEndpoints(this WebApplication app)
    {
        // Adding health checks endpoints to applications in non-development environments has security implications.
        // See https://aka.ms/dotnet/aspire/healthchecks for details before enabling these endpoints in non-development environments.
        if (app.Environment.IsDevelopment())
        {
            // All health checks must pass for app to be considered ready to accept traffic after starting
            app.MapHealthChecks("/health");

            // Only health checks tagged with the "live" tag must pass for app to be considered alive
            app.MapHealthChecks("/alive", new HealthCheckOptions
            {
                Predicate = r => r.Tags.Contains("live")
            });
        }

        return app;
    }
}