.NET Aspire：以正确的方式构建云原生应用程序

dotnet workload update
dotnet workload install aspire

dotnet new aspire-starter -n MyCloudApp

dotnet run --project MyCloudApp.AppHost

var builder = DistributedApplication.CreateBuilder(args);

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

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

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

// Application services
var catalogApi = builder.AddProject<Projects.CatalogApi>("catalog-api")
    .WithReference(postgres)
    .WithReference(redis)
    .WithReference(rabbitmq);

var orderApi = builder.AddProject<Projects.OrderApi>("order-api")
    .WithReference(postgres)
    .WithReference(rabbitmq);

var frontend = builder.AddProject<Projects.WebFrontend>("frontend")
    .WithExternalHttpEndpoints()
    .WithReference(catalogApi)
    .WithReference(orderApi);

builder.Build().Run();
```大声读出该代码。它实际上记录了自己。 “目录 API 引用了 PostgreSQL、Redis 和 RabbitMQ。前端引用了目录 API 和订单 API。”这就是您的架构，用代码表达。

有几点值得注意：

- **`WithReference`** 承担繁重的工作。它通过环境变量和配置自动将连接字符串和服务 URL 注入到使用项目中。您的服务不需要知道 Redis 在“哪里”运行 — Aspire 会处理它。
- **`WithPgAdmin()`** 和 **`WithManagementPlugin()`** 在实际服务旁边启动 PostgreSQL 和 RabbitMQ 的管理 UI。在开发过程中，这些都是无价的。
- **`WithExternalHttpEndpoints()`** 将服务标记为可外部访问，这在部署时很重要。

### 资源配置

您可以通过细粒度控制来配置资源：

```csharp
var postgres = builder.AddPostgres("postgres")
    .WithEnvironment("POSTGRES_MAX_CONNECTIONS", "200")
    .WithDataVolume("postgres-data")
    .AddDatabase("catalogdb");

var redis = builder.AddRedis("cache")
    .WithDataVolume("redis-data");

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;
    }

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

        builder.Services.AddOpenTelemetry()
            .WithMetrics(metrics =>
            {
                metrics.AddAspNetCoreInstrumentation()
                    .AddHttpClientInstrumentation()
                    .AddRuntimeInstrumentation();
            })
            .WithTracing(tracing =>
            {
                tracing.AddAspNetCoreInstrumentation()
                    .AddHttpClientInstrumentation()
                    .AddGrpcClientInstrumentation();
            });

        builder.AddOpenTelemetryExporters();
        return builder;
    }

    public static IHostApplicationBuilder AddDefaultHealthChecks(
        this IHostApplicationBuilder builder)
    {
        builder.Services.AddHealthChecks()
            .AddCheck("self", () => HealthCheckResult.Healthy(),
                ["live"]);

        return builder;
    }
}

var builder = WebApplication.CreateBuilder(args);
builder.AddServiceDefaults();

// Your service-specific configuration...

var app = builder.Build();
app.MapDefaultEndpoints();
app.Run();

var builder = WebApplication.CreateBuilder(args);
builder.AddServiceDefaults();
builder.AddRedisDistributedCache("cache");

builder.AddRedisOutputCache("cache");

builder.AddNpgsqlDbContext<CatalogDbContext>("catalogdb", settings =>
{
    settings.DisableRetry = false;
});

builder.AddRabbitMQClient("messaging");

// Azure Blob Storage
builder.AddAzureBlobClient("blobs");

// Azure Service Bus
builder.AddAzureServiceBusClient("servicebus");

// Azure Key Vault
builder.AddAzureKeyVaultClient("secrets");
```模式始终相同：AppHost 中的一行用于定义资源，消费服务中的一行用于使用它。连接详细信息会自动流动。

## 开发者仪表板

Aspire 仪表板是那些看起来很不错的功能之一，直到您真正使用它为止，然后您就无法想象没有它会如何工作。

当您在本地运行 AppHost 时，仪表板将启动并为您提供：

- **资源概览** — 您的所有服务和基础设施一目了然，并带有状态指示器
- **结构化日志** — 来自每个服务的实时日志流，可过滤和可搜索
- **分布式跟踪** - 跨越多个服务的端到端请求跟踪，可视化为火焰图
- **指标** — 实时 HTTP 请求率、错误率、延迟和自定义指标
- **控制台日志** - 来自每个容器和项目的原始 stdout/stderr

分布式追踪尤其有价值。当请求到达您的前端、流经目录 API、触及 Redis 和 PostgreSQL 时，您会看到整个链以及每个跃点的时间。不再猜测瓶颈在哪里。

我发现仪表板在调试过程中最有用。一切都集中在一处，并通过关联 ID 跨服务链接相关事件，而不是跟踪多个终端窗口或在日志文件之间跳转。

仪表板还可以作为独立容器使用，这意味着您可以在临时环境或 CI 管道中使用它：

```bash
docker run --rm -p 18888:18888 \
  mcr.microsoft.com/dotnet/aspire-dashboard:latest

azd init
azd up

dotnet tool install -g aspirate
aspirate generate
aspirate apply

var postgres = builder.AddPostgres("postgres")
    .AddDatabase("catalogdb")
    .WithHealthCheck();

public static class AppHostExtensions
{
    public static IResourceBuilder<ProjectResource> AddWorkerService(
        this IDistributedApplicationBuilder builder,
        string name,
        IResourceBuilder<IResourceWithConnectionString> db,
        IResourceBuilder<IResourceWithConnectionString> messaging)
    {
        return builder.AddProject<Projects.WorkerService>(name)
            .WithReference(db)
            .WithReference(messaging)
            .WithReplicas(3);
    }
}

var catalogApi = builder.AddProject<Projects.CatalogApi>("catalog-api")
    .WithReference(postgres)
    .WithReference(redis)
    .WithReplicas(5);

var dbPassword = builder.AddParameter("db-password", secret: true);

var postgres = builder.AddPostgres("postgres", password: dbPassword)
    .AddDatabase("catalogdb");

[Fact]
public async Task CatalogApiReturnsProducts()
{
    var appHost = await DistributedApplicationTestingBuilder
        .CreateAsync<Projects.MyCloudApp_AppHost>();

    await using var app = await appHost.BuildAsync();
    await app.StartAsync();

    var httpClient = app.CreateHttpClient("catalog-api");
    var response = await httpClient.GetAsync("/api/products");

    response.EnsureSuccessStatusCode();

    var products = await response.Content
        .ReadFromJsonAsync<List<Product>>();
    Assert.NotEmpty(products);
}

var redis = builder.AddRedis("cache")
    .WithContainerRuntimeArgs("--memory=256m");