通过 Ocelot 实现 API 网关

通过 Ocelot 实现 API 网关

API 网关

API网关是一个服务器，是系统的唯一入口，为每个客户端提供一个定制的API。它可能还具有其它职责，如身份验证、监控、负载均衡、缓存、请求分片与管理、静态响应处理。

Ocelot

Ocelot是一个用 .Net Core 实现并且开源的API网关，它功能强大，包括了：路由、请求聚合、服务发现、认证、鉴权、限流熔断、并内置了负载均衡器与Service Fabric、Butterfly Tracing集成。

安装依赖

Install-Package Ocelot

创建 Gateway.API

• Startup.cs中 配置如下

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


public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    app.UseOcelot();
}
        

• 在 Gateway.API 中新建名为 Ocelot.json的json配置文件

具体配置项请参照官方文档配置

{
  "Routes": [
    /*
        ## User.API
           用户服务
    */
    {
      "DownstreamScheme": "http",
      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 5001
        }
      ],
      "DownstreamPathTemplate": "/api/user",
      "UpstreamPathTemplate": "/user",
      "UpstreamHttpMethod": [ "Get" ]

      //"AuthenticationOptions": {
      //  "AuthenticationProviderKey": "finbook",
      //  "AllowedScopes": []
      //}

    },

    /*
      ## Contacts.API
         通讯录服务
    */
    {
      //获取联系人信息
      "DownstreamScheme": "http",
      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 5003
        }
      ],
      "DownstreamPathTemplate": "/api/contacts",
      "UpstreamPathTemplate": "/contacts",
      "UpstreamHttpMethod": [ "Get" ]
    },
    {
      //给联系人打标签
      "DownstreamScheme": "http",
      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 5003
        }
      ],
      "DownstreamPathTemplate": "/api/contacts/tags",
      "UpstreamPathTemplate": "/contacts/tags",
      "UpstreamHttpMethod": [ "Put" ]
    },
    {
      //好友申请(添加，通过，获取)
      "DownstreamScheme": "http",
      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 5003
        }
      ],
      "DownstreamPathTemplate": "/api/contacts/apply-request",
      "UpstreamPathTemplate": "/contacts/apply-request",
      "UpstreamHttpMethod": [ "Get", "Post", "Put" ]
    }

  ],
  "GlobalConfiguration": {
    "BaseUrl": "http://localhost:5000"
  }
}

• Program.cs中配置如下

public class Program
{

    public static void Main(string[] args)
    {
        CreateHostBuilder(args).Build().Run();
    }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureAppConfiguration(config=> {
                config                   
                .AddJsonFile("appsettings.json", true, true)
                .AddJsonFile("Ocelot.json");
                
            })
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseStartup<Startup>();
            });
}

调试

• 启动两个API

• 【Gateway.API】：http://localhost:5000/contacts

• 【Contact.API】：http://localhost:5003/api/contacts

实际上在地址栏中请求上游地址 http://localhost:5000/contacts时ocelot会帮我们转发到配置的下游地址http://localhost:5003/api/contacts以上一个简单的网关即搭建完成了

• 在地址栏请求