.Net Core微服务入门——Ocelot API网关接入（一）

.Net Core微服务入门——Ocelot API网关接入

上一章我们测试了一个简单的Client 端访问Consul实现服务注册与发现，但是现实生产环境我们直接通过Client自行连接Consul实现服务注册与发现，基本是不可行的，我们需要一个统一的入口来连接客户端与服务，统一管理，并做安全认证等。

所以，这里就需要用到Ocelot

Ocelot
官网：https://ocelot.readthedocs.io/
Ocelot正是为.Net微服务体系提供一个统一的入口点，称为：Gateway（网关）。

新建Ocelot项目

1、创建一个空的asp.net core web项目。

2、引入Ocelot包：

3、新增ocelot.json，配置服务api信息：

{
  "Routes": [
    {
      "DownstreamPathTemplate": "/api/product/getall",
      "DownstreamScheme": "http",
      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 5001
        },
        {
          "Host": "localhost",
          "Port": 5002
        }
      ],
      "UpstreamPathTemplate": "/api/product/getall",
      "UpstreamHttpMethod": [
        "Get"
      ],
      "LoadBalancerOptions": {
        "Type": "RoundRobin" //负载均衡，轮询机制 LeastConnection/RoundRobin/NoLoadBalancer/CookieStickySessions
      }
    }
  ],
  "GlobalConfiguration": {
    "BaseUrl": "http://localhost:5010"
  }
}

这里我们先忽略 Consul，采用直连API服务，因为Consul、Ocelot等组件都是可以独立存在的。

配置文件中的Routes节点用来配置路由：
Downstream代表下游，也就是服务实例，就是我们的服务api地址
如：http://192.168.8.61:5001/api/product/getall
Upstream代表上游，也就是提供给客户端调用的api地址
如：http://192.168.8.61:5010/api/product/getall，
如果这里改成 api1/product/getall，那么客户端访问的api地址就是 http://192.168.8.61:5010/api1/product/getall
上游的路径不一定要和下游一致，可自行配置

LoadBalancerOptions节点用来配置负载均衡：
Ocelot内置了 LeastConnection、RoundRobin、NoLoadBalancer、CookieStickySessions 4种负载均衡策略。
LeastConnection -最少连接，跟踪哪些服务正在处理请求，并把新请求发送到现有请求最少的服务上。该算法状态不在整个Ocelot集群中分布。
RoundRobin - 轮询可用的服务并发送请求。 该算法状态不在整个Ocelot集群中分布。
NoLoadBalancer - 不负载均衡，从配置或服务发现提供程序中取第一个可用的下游服务。
CookieStickySessions - 使用cookie关联所有相关的请求到制定的服务。

BaseUrl节点就是配置我们ocelot网关将要运行的地址。

4、修改Program.cs：

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

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

5、修改Startup.cs

public class Startup
{
    // This method gets called by the runtime. Use this method to add services to the container.
    // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
    public void ConfigureServices(IServiceCollection services)
    {
        //添加ocelot服务
        services.AddOcelot();

    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        //设置Ocelot中间件
        app.UseOcelot().Wait();

    }
}

6、运行Oeclot项目

我们先手动运行 ，直接进入bin目录下，执行控制台命令：`dotnet Ocelot.APIGateway.dll --urls=“http://*:5010”

浏览器访问 http://192.168.8.61:5010/api/product/getall

这里说明Ocelot网关正常运行了，下一步，我们client接入网关

7、修改Client

IGatewayServiceHelper. cs

public interface IGatewayServiceHelper
    {
        /// <summary>
        /// 获取产品数据
        /// </summary>
        /// <returns></returns>
        Task<string> GetProduct();


        /// <summary>
        /// 获取服务列表
        /// </summary>
        void GetServices();
    }

GatewayServiceHelper.cs

 public class GatewayServiceHelper: IGatewayServiceHelper
    {
        public async Task<string> GetProduct()
        {
            var Client = new RestClient("http://localhost:5010");
            var request = new RestRequest("/api/product/getall", Method.GET);

            var response = await Client.ExecuteAsync(request);
            return response.Content;
        }

        public void GetServices()
        {
            throw new NotImplementedException();
        }
    }

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.AddControllers();

        注入IServiceHelper
        //services.AddSingleton<IServiceHelper, ServiceHelper>();

        //注入IServiceHelper
        services.AddSingleton<IGatewayServiceHelper, GatewayServiceHelper>();

        注入IServiceHelper
        //services.AddSingleton<IServiceHelper, GatewayServiceHelper>();
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    //public void Configure(IApplicationBuilder app, IWebHostEnvironment env, IServiceHelper serviceHelper)
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseHttpsRedirection();

        app.UseRouting();

        app.UseAuthorization();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapControllers();
        });

        //程序启动时 获取服务列表
        //serviceHelper.GetServices();
    }
}

ProductsController.cs

[Produces("application/json")]
[Route("product")]
 public class ProductsController
 {
     private readonly IGatewayServiceHelper _serviceHelper;

     public ProductsController(IGatewayServiceHelper serviceHelper)
     {
         _serviceHelper = serviceHelper;
     }
     /// <summary>
     /// 获取产品列表
     /// </summary>
     /// <returns>产品列表</returns>
     [Route("GetAll")]
     [HttpGet]
     public List<Product> GetAllProducts()
     {
         var result = _serviceHelper.GetProduct();
         if (!string.IsNullOrWhiteSpace(result.Result))
         {
             var json = result.Result;
             //将Json转换回图书列表
             var products = JsonConvert.DeserializeObject<List<Product>>(json);
             return products;
         }

         return null;
     }
 }

调试启动Client,浏览器自动打开：https://localhost:44393/product/getall

Client顺利连上了网关层。

有人问，那我api有多个接口怎么办呢，总不能每个接口都配置一下吧。
多个接口的话，只需要修改ocelot.json即可，将具体api接口 改成 api/{url}

{
  "Routes": [
    {
      "DownstreamPathTemplate": "/api/{url}",
      "DownstreamScheme": "http",
      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 5001
        },
        {
          "Host": "localhost",
          "Port": 5002
        }
      ],
      "UpstreamPathTemplate": "/api/{url}",
      "UpstreamHttpMethod": [
        "Get"
      ],
      "LoadBalancerOptions": {
        "Type": "RoundRobin" //负载均衡，轮询机制 LeastConnection/RoundRobin/NoLoadBalancer/CookieStickySessions
      }
    }
  ],
  "GlobalConfiguration": {
    "BaseUrl": "http://localhost:5010"
  }
}

那如果有多个Service呢

{
  "Routes": [
    {
      "DownstreamPathTemplate": "/api/{url}",
      "DownstreamScheme": "http",
      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 5001
        },
        {
          "Host": "localhost",
          "Port": 5002
        }
      ],
      "UpstreamPathTemplate": "/api/{url}",
      "UpstreamHttpMethod": [
        "Get"
      ],
      "LoadBalancerOptions": {
        "Type": "RoundRobin" //负载均衡，轮询机制 LeastConnection/RoundRobin/NoLoadBalancer/CookieStickySessions
      }
    },
    {
      "DownstreamPathTemplate": "/api/{url}",
      "DownstreamScheme": "http",
      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 5005
        },
        {
          "Host": "localhost",
          "Port": 5006
        }
      ],
      "UpstreamPathTemplate": "/api/{url}",
      "UpstreamHttpMethod": [
        "Get"
      ],
      "LoadBalancerOptions": {
        "Type": "RoundRobin" //负载均衡，轮询机制 LeastConnection/RoundRobin/NoLoadBalancer/CookieStickySessions
      }
    }
  ],
  "GlobalConfiguration": {
    "BaseUrl": "http://localhost:5010"
  }
}

下一章，我们将继续深入，探讨Ocelot 连接 Consul，服务治理等

https://blog.csdn.net/weixin_41003771/article/details/119177786