aspire

.NET Aspire

Core Principles

1. AppHost orchestrates; it is never deployed itself — Aspire's core job is the local development experience: starting services, databases, and message brokers together. Modern Aspire also generates deployment assets (aspire publish for docker-compose/Kubernetes manifests, aspire deploy for Azure Container Apps) — but the AppHost process itself stays a dev/build-time tool, not a production runtime.
2. Service defaults are your baseline — The ServiceDefaults project configures OpenTelemetry, health checks, and resilience for all services in one place.
3. Use Aspire integrations — Aspire has built-in integrations for PostgreSQL, Redis, RabbitMQ, SQL Server, and more. They handle connection strings, health checks, and tracing automatically.
4. The dashboard is your observability tool — Use the Aspire dashboard for local development tracing, logging, and metrics instead of setting up Seq/Grafana locally.

Patterns

AppHost Configuration

// AppHost/Program.cs
var builder = DistributedApplication.CreateBuilder(args);

// Infrastructure resources
var postgres = builder.AddPostgres("postgres")
    .WithPgAdmin()
    .AddDatabase("myappdb");

var redis = builder.AddRedis("redis")
    .WithRedisInsight();

var rabbitmq = builder.AddRabbitMQ("messaging")
    .WithManagementPlugin();

// Application projects
var api = builder.AddProject<Projects.MyApp_Api>("api")
    .WithReference(postgres)
    .WithReference(redis)
    .WithReference(rabbitmq)
    .WithExternalHttpEndpoints();

var worker = builder.AddProject<Projects.MyApp_Worker>("worker")
    .WithReference(postgres)
    .WithReference(rabbitmq);

builder.Build().Run();

Service Defaults

// ServiceDefaults/Extensions.cs — Standard Aspire service defaults
// Configures OpenTelemetry (metrics + tracing), health checks, service discovery, and resilience
public static class Extensions
{
    public static IHostApplicationBuilder AddServiceDefaults(this IHostApplicationBuilder builder)
    {
        builder.ConfigureOpenTelemetry();
        builder.AddDefaultHealthChecks();
        builder.Services.AddServiceDiscovery();

        builder.Services.ConfigureHttpClientDefaults(http =>
        {
            http.AddStandardResilienceHandler();
            http.AddServiceDiscovery();
        });

        return builder;
    }

    // ConfigureOpenTelemetry: adds logging, metrics (ASP.NET, HttpClient, Runtime),
    //   tracing (ASP.NET, HttpClient, EF Core), and OTLP exporter if configured
    // AddDefaultHealthChecks: adds a "self" liveness check tagged ["live"]
}