.Net Core 商城微服務項目系列（二）：使用Ocelot + Consul構建具備服務注冊和發現功能的網關...

1.服務注冊

在上一篇的鑒權和登錄服務中分別通過NuGet引用Consul這個包，同時新增AppBuilderExtensions類：

    public static class AppBuilderExtensions{public static IApplicationBuilder RegisterConsul(this IApplicationBuilder app,IApplicationLifetime lifetime,ServiceEntity serviceEntity){var consulClient = new ConsulClient(x => x.Address = new Uri($"http://{serviceEntity.ConsulIP}:{serviceEntity.ConsulPort}"));//請求注冊的Consul地址var httpCheck = new AgentServiceCheck(){DeregisterCriticalServiceAfter=TimeSpan.FromSeconds(5),//服務啟動多久后注冊Interval=TimeSpan.FromSeconds(10),//健康檢查時間間隔，或者成為心跳間隔HTTP=$"http://{serviceEntity.IP}:{serviceEntity.Port}/api/health",//健康檢查地址Timeout=TimeSpan.FromSeconds(5)};//Register service with consulvar registration = new AgentServiceRegistration(){Checks = new[] {httpCheck},ID=Guid.NewGuid().ToString(),Name=serviceEntity.ServiceName,Address=serviceEntity.IP,Port=serviceEntity.Port,Tags = new[] { $"urlprefix-/{serviceEntity.ServiceName}"} //添加urlprefix-/servicename格式的tag標簽，以便Fabio識別
            };consulClient.Agent.ServiceRegister(registration).Wait();//服務啟動時注冊，內部實現其實就是使用Consul API進行注冊（HttpClient發起)lifetime.ApplicationStopping.Register(() =>{consulClient.Agent.ServiceDeregister(registration.ID).Wait();//服務停止時取消注冊
            });return app;}}public class ServiceEntity{public string IP { get; set; }public int Port { get; set; }public string ServiceName { get; set; }public string ConsulIP { get; set; }public int ConsulPort { get; set; }}

通過這個類可以提供服務注冊的基本參數。

修改Startup啟動項中的Configure方法：

public void Configure(IApplicationBuilder app, IHostingEnvironment env, IApplicationLifetime lifetime){if (env.IsDevelopment()){app.UseDeveloperExceptionPage();}#region Consul 服務注冊ServiceEntity serviceEntity = new ServiceEntity{IP = "127.0.0.1",   //服務運行地址Port = Convert.ToInt32(Configuration["Consul:ServicePort"]), //服務運行端口ServiceName = Configuration["Consul:Name"], //服務標識,Ocelot中會用到ConsulIP = Configuration["Consul:IP"], //Consul運行地址ConsulPort = Convert.ToInt32(Configuration["Consul:Port"])  //Consul運行端口（默認8500）
            };app.RegisterConsul(lifetime, serviceEntity);#endregionapp.UseIdentityServer();//app.UseAuthentication();
            app.UseStaticFiles();app.UseMvcWithDefaultRoute();}

看下配置文件需要新增的東西：

{"Service": {"Name": "MI.Service","Port": "7001","DocName": "Account Service","Version": "v1","Title": "Account Service API"},"Identity": {"IP": "localhost","Port": "7000","Scheme": "Bearer"},"ConnectionStrings": {"SqlConnection": "server=.;uid=sa;pwd=sa;database=MI"},"Consul": {"Name": "MI.Service.Account","ServiceProt": "7001","IP": "localhost","Port": "8500"}
}

藍色標識的Consul部分是我們這里需要用到的，這里我把項目名稱當作服務注冊標識。

然后還需要為兩個服務添加兩個方法，一個是用來做健康檢查的，一個是用來測試的：

    [Route("api/Health")]public class HealthController : Controller{[HttpGet]public IActionResult Get() => Ok("ok");}

public class MiUserController : Controller{public MIContext _context;public MiUserController(MIContext _context){this._context = _context;}public string Index(){return "Successful";}。。。。。。
}

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通過“consul agent -dev”命令運行Consul，訪問127.0.0.1：8500我們可以看到Consul的UI界面：

這里可以看到我們已經注冊的兩個服務。

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2.服務發現

新建API項目MI.Ocelot，通過NuGet引用Ocelot和Ocelot.Provider.Consul兩個包，并修改啟動項注冊Ocelot和Consul：

public void ConfigureServices(IServiceCollection services){//services.AddMvc();
            services.AddOcelot(Configuration).AddConsul();}// 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.UseOcelot();//app.UseMvc();  }

然后添加配置文件consul.json:

{"ReRoutes": [{"UseServiceDiscovery": true, //啟用服務發現"DownstreamPathTemplate": "/Account/{url}", //下游轉發路由"DownstreamScheme": "http", //標識頭"ServiceName": "MI.Service.Account", //服務注冊標識"LoadBalancer": "RoundRobin", //服務均衡：輪詢"UpstreamPathTemplate": "/Account/{url}", //上游請求路由"UpstreamHttpMethod": [ "Get", "Post" ], //請求的方法類型"ReRoutesCaseSensitive": false //不區分大小寫
    },{"UseServiceDiscovery": true,"DownstreamPathTemplate": "/Identity/{url}","DownstreamScheme": "http","ServiceName": "MI.Service.IdentityServer","LoadBalancer": "RoundRobin","UpstreamPathTemplate": "/Identity/{url}","UpstreamHttpMethod": [ "Get", "Post" ],"ReRoutesCaseSensitive": false}],"GlobalConfiguration": {//"BaseUrl": "http://localhost:7003","ServiceDiscoveryProvider": {"Host": "127.0.0.1", // Consul Service IP"Port": 8500, // Consul Service Port"Type": "PollConsul","PollingInterval": 100 //健康檢查時間端
    }}
}

在Program中啟用這個配置文件：

        public static IWebHost BuildWebHost(string[] args) =>WebHost.CreateDefaultBuilder(args).UseStartup<Startup>().ConfigureAppConfiguration((hostingContext,builder)=> {builder.AddJsonFile("consul.json");}).Build();

到此，網關配置完畢。現在我將網關項目MI.Gateway部署在7003端口，登錄服務MI.Service.Account部署在7001端口，鑒權服務部署在7000端口，我會通過訪問網關服務來請求登錄服務：

這里的流程是這樣的，Ocelot通過“/Account/MiUser/Index”匹配到了“/Account/{url}”這個路由，進而拿到了“MI.Service.Account”這個服務注冊標識，然后通過Consul拿到了對應的地址，并轉發了請求，同時返回結果。

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到此，具備服務注冊和發現的簡單網關服務就搭建完畢了，后面有時間會繼續優化，添加限流、熔斷，同時身份驗證會在Ocelot中進行，而不是再去訪問單獨的鑒權服務。

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