.Net Aspire初体验

今天参加了Post Microsoft Build & AI Day深圳的集会，众多大佬分享了非常优质前沿的技术和实践，实在受益良多，为了消化吸收关于张队分享的.Net Aspire的内容，特实操一遍小示例并记录如下：

1、以VS2022为例，先升级到最新的版本v17.10.3，新建.NET Aspire Starter应用程序项目，选择文件夹及Redis勾选和勾选生成Tests（HTTPS不能去除勾选）。

生成的文件夹结构如下：

可以看到按模板生成了一个ApiService（这里是以前的天气广播内容）；一个Web项目；一个AppHost（ 一个Host，把ApiService及Web前端给引用进来）；一个ServiceDefaults扩展类；一个Tests测试项目。

AspireApp1.ApiService项目的主要内容：

Program.cs：

 1 var builder = WebApplication.CreateBuilder(args);
 2
 3 // Add service defaults & Aspire components.
 4 builder.AddServiceDefaults();
 5
 6 // Add services to the container.
 7 builder.Services.AddProblemDetails();
 8
 9 var app = builder.Build();
10
11 // Configure the HTTP request pipeline.
12 app.UseExceptionHandler();
13
14 var summaries = new[]
15 {
16     "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
17 };
18
19 app.MapGet("/weatherforecast", () =>
20 {
21     var forecast = Enumerable.Range(1, 5).Select(index =>
22         new WeatherForecast
23         (
24             DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
25             Random.Shared.Next(-20, 55),
26             summaries[Random.Shared.Next(summaries.Length)]
27         ))
28         .ToArray();
29     return forecast;
30 });
31
32 app.MapDefaultEndpoints();
33
34 app.Run();
35
36 record WeatherForecast(DateOnly Date, int TemperatureC, string? Summary)
37 {
38     public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
39 }

AspireApp1.Web项目的主要内容：

Program.cs：

 1 using AspireApp1.Web;
 2 using AspireApp1.Web.Components;
 3
 4 var builder = WebApplication.CreateBuilder(args);
 5
 6 // Add service defaults & Aspire components.
 7 builder.AddServiceDefaults();
 8
 9 // Add services to the container.
10 builder.Services.AddRazorComponents()
11     .AddInteractiveServerComponents();
12
13 builder.Services.AddOutputCache();
14
15 builder.Services.AddHttpClient<WeatherApiClient>(client => client.BaseAddress = new("http://apiservice"));
16
17 var app = builder.Build();
18
19 if (!app.Environment.IsDevelopment())
20 {
21     app.UseExceptionHandler("/Error", createScopeForErrors: true);
22 }
23
24 app.UseStaticFiles();
25 app.UseAntiforgery();
26
27 app.UseOutputCache();
28
29 app.MapRazorComponents<App>()
30     .AddInteractiveServerRenderMode();
31
32 app.MapDefaultEndpoints();
33
34 app.Run();

WeatherApiClient.cs：

 1 namespace AspireApp1.Web;
 2
 3 public class WeatherApiClient(HttpClient httpClient)
 4 {
 5     public async Task<WeatherForecast[]> GetWeatherAsync(int maxItems = 10, CancellationToken cancellationToken = default)
 6     {
 7         List<WeatherForecast>? forecasts = null;
 8
 9         await foreach (var forecast in httpClient.GetFromJsonAsAsyncEnumerable<WeatherForecast>("/weatherforecast", cancellationToken))
10         {
11             if (forecasts?.Count >= maxItems)
12             {
13                 break;
14             }
15             if (forecast is not null)
16             {
17                 forecasts ??= [];
18                 forecasts.Add(forecast);
19             }
20         }
21
22         return forecasts?.ToArray() ?? [];
23     }
24 }
25
26 public record WeatherForecast(DateOnly Date, int TemperatureC, string? Summary)
27 {
28     public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
29 }

AspireApp1.ServiceDefaults项目的主要内容：

Extensions.cs：

  1 using Microsoft.AspNetCore.Builder;
  2 using Microsoft.AspNetCore.Diagnostics.HealthChecks;
  3 using Microsoft.Extensions.DependencyInjection;
  4 using Microsoft.Extensions.Diagnostics.HealthChecks;
  5 using Microsoft.Extensions.Logging;
  6 using OpenTelemetry;
  7 using OpenTelemetry.Metrics;
  8 using OpenTelemetry.Trace;
  9
 10 namespace Microsoft.Extensions.Hosting;
 11
 12 // Adds common .NET Aspire services: service discovery, resilience, health checks, and OpenTelemetry.
 13 // This project should be referenced by each service project in your solution.
 14 // To learn more about using this project, see https://aka.ms/dotnet/aspire/service-defaults
 15 public static class Extensions
 16 {
 17     public static IHostApplicationBuilder AddServiceDefaults(this IHostApplicationBuilder builder)
 18     {
 19         builder.ConfigureOpenTelemetry();
 20
 21         builder.AddDefaultHealthChecks();
 22
 23         builder.Services.AddServiceDiscovery();
 24
 25         builder.Services.ConfigureHttpClientDefaults(http =>
 26         {
 27             // Turn on resilience by default
 28             http.AddStandardResilienceHandler();
 29
 30             // Turn on service discovery by default
 31             http.AddServiceDiscovery();
 32         });
 33
 34         return builder;
 35     }
 36
 37     public static IHostApplicationBuilder ConfigureOpenTelemetry(this IHostApplicationBuilder builder)
 38     {
 39         builder.Logging.AddOpenTelemetry(logging =>
 40         {
 41             logging.IncludeFormattedMessage = true;
 42             logging.IncludeScopes = true;
 43         });
 44
 45         builder.Services.AddOpenTelemetry()
 46             .WithMetrics(metrics =>
 47             {
 48                 metrics.AddAspNetCoreInstrumentation()
 49                     .AddHttpClientInstrumentation()
 50                     .AddRuntimeInstrumentation();
 51             })
 52             .WithTracing(tracing =>
 53             {
 54                 tracing.AddAspNetCoreInstrumentation()
 55                     // Uncomment the following line to enable gRPC instrumentation (requires the OpenTelemetry.Instrumentation.GrpcNetClient package)
 56                     //.AddGrpcClientInstrumentation()
 57                     .AddHttpClientInstrumentation();
 58             });
 59
 60         builder.AddOpenTelemetryExporters();
 61
 62         return builder;
 63     }
 64
 65     private static IHostApplicationBuilder AddOpenTelemetryExporters(this IHostApplicationBuilder builder)
 66     {
 67         var useOtlpExporter = !string.IsNullOrWhiteSpace(builder.Configuration["OTEL_EXPORTER_OTLP_ENDPOINT"]);
 68
 69         if (useOtlpExporter)
 70         {
 71             builder.Services.AddOpenTelemetry().UseOtlpExporter();
 72         }
 73
 74         // Uncomment the following lines to enable the Azure Monitor exporter (requires the Azure.Monitor.OpenTelemetry.AspNetCore package)
 75         //if (!string.IsNullOrEmpty(builder.Configuration["APPLICATIONINSIGHTS_CONNECTION_STRING"]))
 76         //{
 77         //    builder.Services.AddOpenTelemetry()
 78         //       .UseAzureMonitor();
 79         //}
 80
 81         return builder;
 82     }
 83
 84     public static IHostApplicationBuilder AddDefaultHealthChecks(this IHostApplicationBuilder builder)
 85     {
 86         builder.Services.AddHealthChecks()
 87             // Add a default liveness check to ensure app is responsive
 88             .AddCheck("self", () => HealthCheckResult.Healthy(), ["live"]);
 89
 90         return builder;
 91     }
 92
 93     public static WebApplication MapDefaultEndpoints(this WebApplication app)
 94     {
 95         // Adding health checks endpoints to applications in non-development environments has security implications.
 96         // See https://aka.ms/dotnet/aspire/healthchecks for details before enabling these endpoints in non-development environments.
 97         if (app.Environment.IsDevelopment())
 98         {
 99             // All health checks must pass for app to be considered ready to accept traffic after starting
100             app.MapHealthChecks("/health");
101
102             // Only health checks tagged with the "live" tag must pass for app to be considered alive
103             app.MapHealthChecks("/alive", new HealthCheckOptions
104             {
105                 Predicate = r => r.Tags.Contains("live")
106             });
107         }
108
109         return app;
110     }
111 }

AspireApp1.AppHost项目的主要内容：

Program.cs：

1 var builder = DistributedApplication.CreateBuilder(args);
2
3 var apiService = builder.AddProject<Projects.AspireApp1_ApiService>("apiservice");
4
5 builder.AddProject<Projects.AspireApp1_Web>("webfrontend")
6     .WithExternalHttpEndpoints()
7     .WithReference(apiService);
8
9 builder.Build().Run();

还有一个Tests测试项目的内容：

WebTests.cs：

 1 using System.Net;
 2
 3 namespace AspireApp1.Tests;
 4
 5 public class WebTests
 6 {
 7     [Fact]
 8     public async Task GetWebResourceRootReturnsOkStatusCode()
 9     {
10         // Arrange
11         var appHost = await DistributedApplicationTestingBuilder.CreateAsync<Projects.AspireApp1_AppHost>();
12         await using var app = await appHost.BuildAsync();
13         await app.StartAsync();
14
15         // Act
16         var httpClient = app.CreateHttpClient("webfrontend");
17         var response = await httpClient.GetAsync("/");
18
19         // Assert
20         Assert.Equal(HttpStatusCode.OK, response.StatusCode);
21     }
22 }

2、我们将AspireApp1.AppHost项目设为启动项目，按F5运行。项目即启动生成和运行，可在输出窗口看到对应信息。等程序运行起来会自动打开一个浏览器概览仪表盘窗口如下：

点击对应项目的终结点，即可看到对应的内容：

AspireApp1.ApiService：

AspireApp1.Web：

在仪表盘可以看到资源、控制台、结构化、跟踪、指标几个栏目，没有写一句代码，你的可观测、生产就绪的云原生分布式应用程序就搭建完成了。

以下是一些图示：

另外多嘴一句，并不是用了Aspire就一定要上云，我突然有个主意，边缘运算、单体程序照样也可以用Aspire。另外Aspire和Dapr应该是有益的补充，而不是替代关系。