如何使用 Consul 自行注册服务

Question

我正在尝试 self 在启动时将我的 ASP.NET 核心应用程序注册到 Consul 注册表，并在关闭时注销它。

从 here 我可以了解到调用 http api [put /v1/agent/service/register] 可能是可行的方法（或者可能不是！）。

在我的应用程序中，我想我将以 Startup class 为目标，首先添加我的 .json 文件

public Startup(IHostingEnvironment env)
{
   var builder = new Configuration().AddJsonFile("consulconfig.json");
   Configuration = builder.Build();
}

但是现在，我被卡住了，因为 ConfigureServices 方法告诉我那是我向容器添加服务的地方，而 Configure 方法是我配置 Http 请求管道的地方。

有人能给我指出正确的方向、在线阅读、示例等。

Answer 1

首先我推荐使用Consul.NET 与领事互动。使用它，服务注册可能如下所示：

var registration = new AgentServiceRegistration
{
    Name = "foo",
    Port = 4242,
    Address = "http://bar"
};

using (var client = new ConsulClient())
{
    await client.Agent.ServiceRegister(registration);
}

现在让我们借助 DI 和松散耦合将此代码集成到 ASP.NET 核心启动过程中。将您的 json 文件读入 ConsulOptions 实例（没有任何逻辑的 DTO）：

public void ConfigureServices(IServiceCollection services)
{
    services.AddOptions();
    services.Configure<ConsulOptions>(Configuration);
}

将所有与 Consul 相关的逻辑封装在 class ConsulService 中接受 ConsulOptions 作为依赖：

public class ConsulService : IDisposable
{
    public ConsulService(IOptions<ConsulOptions> optAccessor) { }

    public void Register() 
    {
        //possible implementation of synchronous API
        client.Agent.ServiceRegister(registration).GetAwaiter().GetResult();
    }
}

将 class 本身添加到 DI 容器中：

services.AddTransient<ConsulService>();

然后创建IApplicationBuilder的扩展方法并调用它：

public void Configure(IApplicationBuilder app)
{
    app.ConsulRegister();
}

在 ConsulRegister 实现中，我们在应用程序 start/stop:

上添加挂钩

public static class ApplicationBuilderExtensions
{
    public static ConsulService Service { get; set; }

    public static IApplicationBuilder ConsulRegister(this IApplicationBuilder app)
    {
        //design ConsulService class as long-lived or store ApplicationServices instead
        Service = app.ApplicationServices.GetService<ConsulService>();

        var life = app.ApplicationServices.GetService<IApplicationLifetime>();

        life.ApplicationStarted.Register(OnStarted);
        life.ApplicationStopping.Register(OnStopping);

        return app;
    }

    private static void OnStarted()
    {
        Service.Register(); //finally, register the API in Consul
    }
}

锁定缺失和静态字段是可以的，因为 Startup class 在应用程序启动时只执行一次。不要忘记在 OnStopping 方法中取消注册 API！

Answer 2

Startup.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;

namespace WebApplication1
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddConsulConfig(Configuration);
            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            app.UseConsul();
            app.UseMvc();
        }
    }
}

AppExtensions.cs

using Consul;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace WebApplication1
{
    public static class AppExtensions
    {
        public static IServiceCollection AddConsulConfig(this IServiceCollection services, IConfiguration configuration)
        {
            services.AddSingleton<IConsulClient, ConsulClient>(p => new ConsulClient(consulConfig =>
            {
                var address = configuration.GetValue<string>("http://localhost:8500");
                consulConfig.Address = new Uri(address);
            }));
            return services;
        }

        public static IApplicationBuilder UseConsul(this IApplicationBuilder app)
        {
            var consulClient = app.ApplicationServices.GetRequiredService<IConsulClient>();
            var logger = app.ApplicationServices.GetRequiredService<ILoggerFactory>().CreateLogger("AppExtensions");
            var lifetime = app.ApplicationServices.GetRequiredService<IApplicationLifetime>();


            // var uri = new Uri(address);
            // Better approach should be used to set the below settings. I hard coded just to explain.
            var registration = new AgentServiceRegistration()
            {
                ID = $"MyService",
                Name = "WebApplication1",
                Address = "localhost", //$"{uri.Host}",
                Port = 57084  // uri.Port
            };

            logger.LogInformation("Registering with Consul");
            consulClient.Agent.ServiceDeregister(registration.ID).ConfigureAwait(true);
            consulClient.Agent.ServiceRegister(registration).ConfigureAwait(true);

            lifetime.ApplicationStopping.Register(() =>
            {
                logger.LogInformation("Unregistering from Consul");
                consulClient.Agent.ServiceDeregister(registration.ID).ConfigureAwait(true);
            });

            return app;
        }
    }
}

Github repo

如何使用 Consul 自行注册服务

How to self register a service with Consul

c#

asp.net-core

microservices

consul