开发环境
操作系统：版本 Windows 10 专业版 操作系统内部版本 19042.1165
开发工具：Microsoft Visual Studio Community 2019版本 16.10.0
开发框架：ASP.NET Core 3.1
本文相关Nuget包：
Ocelot -Version 16.0.1
Swashbuckle.AspNetCore 5.6.3

一、搭建一个webapi项目OcelotGateway31
1、安装 Ocelot 与 Swashbuckle.AspNetCore 包

2、添加Ocelot的配置文件ocelot.json
在启动文件Program.cs中设置项目启动读取ocelot.json配置文件

  public static IHostBuilder CreateHostBuilder(string[] args) =>
                    Host.CreateDefaultBuilder(args)
                        .ConfigureAppConfiguration(c =>
                        {
                            c.AddJsonFile("ocelot.json", optional: false, reloadOnChange: true);
                        })

                     .ConfigureWebHostDefaults(webBuilder =>
                     {
                         webBuilder.UseStartup<Startup>();
                     });

3、OCELOT基本配置
先配置Startup.cs文件。在ConfigureServices()方法中，添加代码：

 services.AddOcelot();

在Configure()方法中，UseRouting()中间件之前，添加Ocelot中间件：

app.UseOcelot().Wait();

在ocelot.json添加内容

{
  "Routes": [
    //APITest1
    {
      "UpstreamPathTemplate": "/api/test1/{url}",
      "UpstreamHttpMethod": [ "Get", "Post", "Put", "PATCH", "Delete", "Options" ],
      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 8801
        }
      ],
      "DownstreamPathTemplate": "/api/test1/{url}",
      "DownstreamScheme": "http",
      "DownstreamHeaderTransform": {
        "Access-Control-Allow-Origin": "http://localhost:8800",
        "Access-Control-Allow-Methods": "*",
        "Access-Control-Allow-Headers": "*"
      }
    },
    //APITest1服务swagger
    {
      "UpstreamPathTemplate": "/test1/swagger/v1/swagger.json",
      "UpstreamHttpMethod": [ "Get" ],
      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 8801
        }
      ],
      "DownstreamPathTemplate": "/swagger/v1/swagger.json",
      "DownstreamScheme": "http"
    },

    //APITest2
    {
      "UpstreamPathTemplate": "/api/test2/{url}",
      "UpstreamHttpMethod": [ "Get", "Post", "Put", "PATCH", "Delete", "Options" ],
      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 8802
        }
      ],
      "DownstreamPathTemplate": "/api/test2/{url}",
      "DownstreamScheme": "http",
      "DownstreamHeaderTransform": {
        "Access-Control-Allow-Origin": "http://localhost:8800",
        "Access-Control-Allow-Methods": "*",
        "Access-Control-Allow-Headers": "*"
      }
    },
    //APITest2服务swagger
    {
      "UpstreamPathTemplate": "/test2/swagger/v1/swagger.json",
      "UpstreamHttpMethod": [ "Get" ],
      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 8802
        }
      ],
      "DownstreamPathTemplate": "/swagger/v1/swagger.json",
      "DownstreamScheme": "http"
    }

  ]
}

4、添加swagger支持
在ConfigureServices()方法中，添加代码：

   services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1",
                    new OpenApiInfo { Title = "Gateway API", Version = "v1", Description = "# gateway api..." });
            });

在Configure()方法中，Ocelot 中间件之前，添加swagger()中间件：

     #region Swagger
            app.UseSwagger();
            app.UseSwaggerUI(c =>
            {
                c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API V1");
                c.SwaggerEndpoint("/test1/swagger/v1/swagger.json", "APITest1  API V1"); 
                c.SwaggerEndpoint("/test2/swagger/v1/swagger.json", "APITest2  API V1");

            });
            #endregion

二、搭建APITest1的Api服务
1、安装 Swashbuckle.AspNetCore 包
2、注册swagger :配置Startup.cs文件。在ConfigureServices()方法中，添加代码：

#region  注册Swagger生成器，定义一个或多个Swagger文档
            services.AddSwaggerGen(c =>
            {
                //Bearer 的scheme定义
                var securityScheme = new OpenApiSecurityScheme()
                {
                    Description = "JWT Authorization header using the Bearer scheme. Example: \"Authorization: Bearer {token}\"",
                    Name = "Authorization",
                    //参数添加在头部
                    In = ParameterLocation.Header,
                    //使用Authorize头部
                    Type = SecuritySchemeType.Http,
                    //内容为以 bearer开头
                    Scheme = "bearer",
                    BearerFormat = "JWT"
                };
                //把所有方法配置为增加bearer头部信息
                var securityRequirement = new OpenApiSecurityRequirement
                        {
                        {
                                new OpenApiSecurityScheme
                                {
                                    Reference = new OpenApiReference
                                    {
                                        Type = ReferenceType.SecurityScheme,
                                        Id = "bearerAuth"
                                    }
                                },
                                new string[] {}
                        }
                        };
                //注册到swagger中
                c.AddSecurityDefinition("bearerAuth", securityScheme);
                c.AddSecurityRequirement(securityRequirement);

                c.SwaggerDoc("v1", new OpenApiInfo
                {
                    Title = "Test1 Web API",
                    Description = "APITest1,添加一个简单的ASP.NET Core Web API示例。",
                    Version = "v1",
                    TermsOfService = new Uri("https://sc.52abp.com"),
                    Contact = new OpenApiContact
                    {
                        Name = "",
                        Email = "11111111@qq.com",
                    },
                });
            });
            #endregion

在Configure()方法中，UseRouting()中间件之前，添加Ocelot中间件：

 app.UseSwagger();
            app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "Test1 v1"));

3、添加Api：HealthController 注意Route 要与网关中的配置中的路由关键字段一致
“test1”

[Route("api/test1/[controller]")]
    [ApiController]
    public class HealthController : ControllerBase
    {
        /// <summary>
        /// 
        /// </summary>
        /// <returns></returns>
        [HttpGet]
        [Route("Index")]
        public string Index()
        {
            string info = $"This is Test1 HealthController  ";
            return info;
        }
    }

三、参照步骤二搭建API服务APITest2
四、调试运行：