Ocelot:API网关概要

一、概要

Ocelot是.Net Core下一个开源API网关；Ocelot主要目标是在.NET在微服务或面向服务架构中提供统一的入口服务，

Ocelot拿到HttpRequest对象到管道后，先创建HttpRequestMessage对象，该对象用于向下游服务发出请求。再将HttpResponseMessage映射到HttpResponse对象上，并返回给客户端。。

主要功能：统一入口、认证、鉴权、限流熔断、内置了负载均衡等等

二、单网关QuickStart

 2.1 API网关

新建.Net Core 2.0 webapi项目:Practice.ApiGetway

 添加Ocelot的Nuget包引用到该项目：Install-Package Ocelot 

修改Startup.cs：

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.AddMvc();
            services.AddOcelot(new ConfigurationBuilder().AddJsonFile("ocelot_config.json").Build());
        }

        // 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().Wait();
            app.UseMvc();
        }
    }

修改Program.cs：

public class Program
    {
        public static void Main(string[] args)
        {
            BuildWebHost(args).Run();
        }

        public static IWebHost BuildWebHost(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseKestrel()
                .UseUrls("http://*:5000")
                .UseContentRoot(Directory.GetCurrentDirectory())
                .UseStartup<Startup>()
                .Build();
    }

 添加一个json文件ocelot_config.json，设置属性：始终复制

{
  "ReRoutes": [

    {
      "DownstreamPathTemplate": "/api/users",
      "DownstreamScheme": "http",
      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 5001
        }
      ],
      "UpstreamPathTemplate": "/users/values",
      "UpstreamHttpMethod": [ "Get" ],
      "QoSOptions": {
        "ExceptionsAllowedBeforeBreaking": 3,
        "DurationOfBreak": 10,
        "TimeoutValue": 5000
      }
    },
    {
      "DownstreamPathTemplate": "/api/news",
      "DownstreamScheme": "http",
      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 5002
        }
      ],
      "UpstreamPathTemplate": "/news/values",
      "UpstreamHttpMethod": [ "Get" ],
      "QoSOptions": {
        "ExceptionsAllowedBeforeBreaking": 3,
        "DurationOfBreak": 10,
        "TimeoutValue": 5000
      }
    }
  ],

  "GlobalConfiguration": {
    //"BaseUrl": "https://api.mybusiness.com"
  }
}

修改launchSettings.json设置个固定的端口

2.2 下游实际API

最后在新建两个API项目：

项目：Practice.NewsApi  、Controller：UsersController、端口：5002

项目：Practice.UsersApi  、Controller：NewsController、端口：5001

运行三个项目

不再截图，运行结果：

访问网关：http://localhost:5000/users/values   会得到 http://localhost:5001/api/users 结果

访问网关：http://localhost:5000/news/values   会得到 http://localhost:5002/api/news  结果

资源：

项目开源地址：https://github.com/ThreeMammals/Ocelot

官方文档：http://ocelot.readthedocs.io/en/latest/

资源：https://github.com/geffzhang/awesome-ocelot

 博客：

http://www.cnblogs.com/jesse2013/p/net-core-apigateway-ocelot-docs.html

 https://www.cnblogs.com/jackcao/