最近在做微服務的時候，由於我們是採用前後端分離來開發的，提供給前端的直接是Swagger，如果Swagger分佈在各個API中，前端檢視Swagger的時候非常不便，因此，我們試著將Swagger集中放到閘道器中。

這裡我用兩個API專案（一個BasicDataApi，一個UsersApi）和一個閘道器專案（ApiGateway）做示例，下面直接上程式碼。

首先在BasicDataApi中配置Swagger：

public void ConfigureServices(IServiceCollection services)
        {
            services.AddMvc();
            services.AddSwaggerGen(options =>
            {
                options.SwaggerDoc("BasicDataApi", new Info { Title = "基礎資料服務", Version = "v1" });
                var basePath = PlatformServices.Default.Application.ApplicationBasePath;
                var xmlPath = Path.Combine(basePath, "Qka.BasicDataApi.xml");
                options.IncludeXmlComments(xmlPath);
            });
        }

        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            app.UseMvc()
                 .UseSwagger(c =>
            {
                c.RouteTemplate = "{documentName}/swagger.json";
            })
                .UseSwaggerUI(options =>
            {
                options.SwaggerEndpoint("/BasicDataApi/swagger.json", "BasicDataApi");
            });
        }

在UsersApi中一樣的配置：

public void ConfigureServices(IServiceCollection services)
        {          
            services.AddSwaggerGen(options =>
            {
                options.SwaggerDoc("UsersApi", new Info { Title = "使用者API介面", Version = "v1" });
                var basePath = PlatformServices.Default.Application.ApplicationBasePath;
                var xmlPath = Path.Combine(basePath, "Qka.UsersApi.xml");
                options.IncludeXmlComments(xmlPath);
            });

            services.AddMvc();
        }

        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            
            app.UseMvc()
                .UseSwagger(c =>
                {
                    c.RouteTemplate = "{documentName}/swagger.json";
                })
                .UseSwaggerUI(options =>
                {
                    options.SwaggerEndpoint("/UsersApi/swagger.json", "UsersApi");
                });
        }                       

　　最後在閘道器專案中修改Ocelot配置，獲取兩個專案的swagger.json不要授權：

  "ReRoutes": [
    {
      "DownstreamPathTemplate": "/UsersApi/swagger.json",
      "DownstreamScheme": "http",
      "ServiceName": "userapi",
      "LoadBalancer": "RoundRobin",
      "UseServiceDiscovery": true,
      "UpstreamPathTemplate": "/UsersApi/swagger.json
 
",
      "UpstreamHttpMethod": [ "GET", "POST", "DELETE", "PUT" ]
    },
    {
      "DownstreamPathTemplate": "/BasicDataApi/swagger.json",
      "DownstreamScheme": "http",
      "ServiceName": "basedataapi",
      "LoadBalancer": "RoundRobin",
      "UseServiceDiscovery": true,
      "UpstreamPathTemplate": "/BasicDataApi/swagger.json",
      "UpstreamHttpMethod": [ "GET", "POST", "DELETE", "PUT" ]
    },
    {
      "DownstreamPathTemplate": "/UsersApi/{url}",
      "DownstreamScheme": "http",
      "ServiceName": "userapi",
      "LoadBalancer": "RoundRobin",
      "UseServiceDiscovery": true,
      "UpstreamPathTemplate": "/UsersApi/{url}",
      "UpstreamHttpMethod": [ "GET", "POST", "DELETE", "PUT" ] ,
      "AuthenticationOptions": {
        "AuthenticationProviderKey": "qka_api",
        "AllowedScopes": []
      }
    }
  ],
  "GlobalConfiguration": {
    "BaseUrl": "http://localhost:9000",
    "ServiceDiscoveryProvider": {
      "Host": "192.168.2.144",
      "Port": 8500
    }
  }
}

修改StartUp.cs檔案的程式碼，注意在使用中介軟體的時候，UseMvc一定要在UseOcelot之前。

：

public void ConfigureServices(IServiceCollection services)
        {
            services.AddOcelot();

            var authenticationProviderKey = "qka_api";
            services.AddAuthentication("Bearer")
                .AddIdentityServerAuthentication(authenticationProviderKey, options =>
                {
                    options.Authority = "http://192.168.2.121:9066/";
                    options.RequireHttpsMetadata = false;
                    options.ApiName = "UserApi";
                });

            services.AddMvc();
            services.AddSwaggerGen(options =>
            {
                options.SwaggerDoc("ApiGateway", new Info { Title = "閘道器服務", Version = "v1" });
            });
        }

        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            app.UseMetricsAllMiddleware();
            app.UseMetricsAllEndpoints();

            app.UseCors("default");

            var apis = new List<string> { "BasicDataApi", "UsersApi" };
            app.UseMvc()
               .UseSwagger()
               .UseSwaggerUI(options =>
               {
                   apis.ForEach(m =>
                   {
                       options.SwaggerEndpoint($"/{m}/swagger.json", m);
                   });
               });

            app.UseOcelot().Wait();
        }

最後上圖：