.NET服務發現(Microsoft.Extensions.ServiceDiscovery)集成Consul

隨著Aspire發佈preview5的發佈,Microsoft.Extensions.ServiceDiscovery隨之更新,

服務註冊發現這個屬於老掉牙的話題解決什麼問題就不贅述了,這裡主要講講Microsoft.Extensions.ServiceDiscovery(preview5)以及如何擴展其他的中間件的發現集成 .

Microsoft.Extensions.ServiceDiscovery官方預設提供的Config,DNS,YARP三種Provider,使用也比較簡單 :

builder.Services.AddServiceDiscovery();

builder.Services.AddHttpClient<CatalogServiceClient>(static client =>
    {
        client.BaseAddress = new("http://todo");
    });

builder.Services.ConfigureHttpClientDefaults(static http =>
{
    // 全局對HttpClient啟用服務發現
    http.UseServiceDiscovery();
});

然後 appsettings.json 為名為 todo 的服務配置終結點：

  "Services": {
    "todo": {
      "http": [
        "http://localhost:5124"
      ]
    }
  }

然後使用服務發現:

#region 模擬服務端的todo介面: 
var sampleTodos = new Todo[] {
    new(1, "Walk the dog"),
    new(2, "Do the dishes", DateOnly.FromDateTime(DateTime.Now)),
    new(3, "Do the laundry", DateOnly.FromDateTime(DateTime.Now.AddDays(1))),
    new(4, "Clean the bathroom"),
    new(5, "Clean the car", DateOnly.FromDateTime(DateTime.Now.AddDays(2)))
};

var todosApi = app.MapGroup("/todos");
todosApi.MapGet("/", () => sampleTodos);
todosApi.MapGet("/{id}", (int id) =>
    sampleTodos.FirstOrDefault(a => a.Id == id) is { } todo
        ? Results.Ok(todo)
        : Results.NotFound());
#endregion

public record Todo(int Id, string? Title, DateOnly? DueBy = null, bool IsComplete = false);

[JsonSerializable(typeof(Todo[]))]
internal partial class AppJsonSerializerContext : JsonSerializerContext
{
}

#region 測試服務發現和負載

app.MapGet("/test", async (IHttpClientFactory clientFactory) =>
{
    //這裡服務發現將自動解析配置文件中的服務
    var client = clientFactory.CreateClient("todo");
    var response = await client.GetAsync("/todos");
    var todos = await response.Content.ReadAsStringAsync();
    return Results.Content(todos, contentType: "application/json");
});

#endregion

運行程式後將會發現成功執行:

當然對於這樣寫死配置的服務發現一點都不靈活,因此應運而生了 YARP和DNS這些Provider, 目前服務註冊發現使用Consul的還是挺多的,當然還有很多其他的輪子就不贅述了,這裡我們來擴展一個Consul的服務發現Provider :

實現核心介面IServiceEndPointProvider

internal class ConsulServiceEndPointProvider(ServiceEndPointQuery query, IConsulClient consulClient, ILogger logger)
        : IServiceEndPointProvider, IHostNameFeature
    {
        const string Name = "Consul";
        private readonly string _serviceName = query.ServiceName;
        private readonly IConsulClient _consulClient = consulClient;
        private readonly ILogger _logger = logger;

        public string HostName => query.ServiceName;

#pragma warning disable CA1816 // Dispose 方法應調用 SuppressFinalize
        public ValueTask DisposeAsync() => default;

        public async ValueTask PopulateAsync(IServiceEndPointBuilder endPoints, CancellationToken cancellationToken)
        {
            var flag = ServiceNameParts.TryParse(_serviceName, out var serviceNameParts);
            var sum = 0;
            if (flag)
            {
                var queryResult = await _consulClient.Health.Service(serviceNameParts.Host, string.Empty, true, cancellationToken);
                foreach (var serviceEntry in queryResult.Response)
                {
                    var address = $"{serviceEntry.Service.Address}:{serviceEntry.Service.Port}";
                    var isEndpoint = ServiceNameParts.TryCreateEndPoint(address, out var endPoint);
                    if (isEndpoint)
                    {
                        ++sum;
                        var serviceEndPoint = ServiceEndPoint.Create(endPoint!);
                        serviceEndPoint.Features.Set<IServiceEndPointProvider>(this);
                        serviceEndPoint.Features.Set<IHostNameFeature>(this);
                        endPoints.EndPoints.Add(serviceEndPoint);
                        _logger.LogInformation($"ConsulServiceEndPointProvider Found Service {_serviceName}:{address}");
                    }
                }
            }

            if (sum == 0)
            {
                _logger.LogWarning($"No ConsulServiceEndPointProvider were found for service '{_serviceName}' ('{HostName}').");
            }
        }

        /// <inheritdoc/>
        public override string ToString() => Name;
    }

實現 IServiceEndPointProviderFactory:

internal class ConsulServiceEndPointProviderFactory(IConsulClient consulClient, ILogger<ConsulServiceEndPointProviderFactory> logger) : IServiceEndPointProviderFactory
    {
        private readonly IConsulClient _consulClient = consulClient;
        private readonly ILogger<ConsulServiceEndPointProviderFactory> _logger = logger;

        public bool TryCreateProvider(ServiceEndPointQuery query, [NotNullWhen(true)] out IServiceEndPointProvider? resolver)
        {
            resolver = new ConsulServiceEndPointProvider(query, _consulClient, _logger);
            return true;
        }
    }

接著擴展一下IServiceCollection

public static IServiceCollection AddConsulServiceEndpointProvider(this IServiceCollection services)
{
	services.AddServiceDiscoveryCore();
	services.AddSingleton<IServiceEndPointProviderFactory, ConsulServiceEndPointProviderFactory>();
	return services;
}

最後添加一行代碼 :

// 使用Microsoft.Extensions.ServiceDiscovery實現負載均衡
builder.Services.AddServiceDiscovery()
    .AddConfigurationServiceEndPointResolver() //config
    .AddConsulServiceEndpointProvider(); //consul

下麵是Consul中註冊完成的服務:

然後我們請求 ./test 調用服務,觀察調試日誌,成功了!

完整的代碼:
https://github.com/vipwan/Biwen.Microsoft.Extensions.ServiceDiscovery.Consul

當然你也可以直接使用nuget引用 Biwen.Microsoft.Extensions.ServiceDiscovery.Consul 我已經發佈到了nuget上 , 最後因為Aspire還在不停的迭代所以Biwen.Microsoft.Extensions.ServiceDiscovery.Consul後面還會存在一些變化, 前面的幾個早期版本我都做了適配以最新的為準