使用Ocelot构建GateWay

添加Nuget包：Ocelot

添加配置文件Ocelot.json 具体配置可以看另一篇 Ocelot配置

Json配置文件主要包含两个根节点：

ReRoutes：路由重定向配置都是数组结构可以配置多个

GlobalConfigrations：全局配置

ReRoutes 主要包含了上下游的路径、方式、限流、负载等设置

我们先配置一个最简单的设置：

这里我做了一个负载，把api部署了2份做了一个简单的分布式，当我访问test的时候会被转发到 9381或者 9384上

{
  "ReRoutes": [
    {
      "DownstreamPathTemplate": "/api/values/getuser",
      "DownstreamScheme": "http",
      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 20001
        },
        {
          "Host": "localhost",
          "Port": 20002
        }
      ],
      "UpstreamPathTemplate": "/test",
      "UpstreamHttpMethod": [ "Get" ],
      "LoadBalancer": "LeastConnection",
      "ServiceName": "userservices",
      "UseServiceDiscovery": true
    }
  ],

  "GlobalConfiguration": {
　　"BaseUrl": "http://localhost:20000",
    "ServiceDiscoveryProvider": {
      "Host": "localhost",
      "Port": 8500

    }

  }
}

这里我结合了Consul来实现，关于Consul的使用可以看官方文档：

需要下载consul.exe程序并将其启动起来这是一个服务发现健康检查的组件如果没有添加系统path设置就直接进入consul.exe目录启动起来

httpServer的默认地址是8500，访问下会进入consul的ui

访问：http://localhost:20000/test

访问：http://localhost:20001/api/values/getuser

得到一样的结果，这里已经被转发了，因为我们配置负载均衡及健康监测

从而保证了在服务器宕机后或者在高QPS下的正常访问

在APIGateWay网关里添加对Ocelot的设置

 public static IWebHost BuildWebHost(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
            .ConfigureAppConfiguration((hostingContext, builder) =>
            {
                builder
                .SetBasePath(hostingContext.HostingEnvironment.ContentRootPath)
                .AddJsonFile("Ocelot.json");
            })
                .UseStartup<Startup>()
            .UseUrls("http://localhost:20000")
                .Build();

添加相关服务注册及configure

services.AddOcelot();

app.UseOcelot().Wait();

网关配置好后，需要对业务接口服务实现健康检查，设置好先关的参数处理consul的频率

DeregisterCriticalServiceAfter 失败多久后注销服务的

Interval 检查发送的评率

HTTP 检查的地址

 applicationLifetime.ApplicationStarted.Register(() =>
            {

                //自动获取当前接口服务地址

                var features = app.Properties["server.Features"] as FeatureCollection;
                var addessess = features.Get<IServerAddressesFeature>().Addresses.Select(url => new Uri(url));

                foreach (var address in addessess)
                {
                  
                    var httpcheck = new AgentServiceCheck()
                    {
                        DeregisterCriticalServiceAfter = TimeSpan.FromMinutes(userappsetting.Value.DeregisterCriticalServiceAfter),
                        Interval = TimeSpan.FromSeconds(userappsetting.Value.Interval),
                        HTTP = new Uri(address, "/api/Check").OriginalString,
                       

                    };
                    //这里可以注入配置
                    var agentReg = new AgentServiceRegistration()
                    {
                        ID = $"{userappsetting.Value.ServiceName}_{address.Host}_{address.Port}",
                        Check = httpcheck,
                        Name = userappsetting.Value.ServiceName,
                        Address = address.Host,
                        Port = address.Port
                      
                    };
                    client.Agent.ServiceRegister(agentReg).ConfigureAwait(false);
                }


            });
            applicationLifetime.ApplicationStopped.Register(() =>
            {
                var features = app.Properties["server.Features"] as FeatureCollection;
                var addessess = features.Get<IServerAddressesFeature>().Addresses.Select(url => new Uri(url));
                foreach (var address in addessess)
                {
                    client.Agent.ServiceDeregister($"{userappsetting.Value.ServiceName}_{address.Host}_{address.Port}").GetAwaiter().GetResult();
                }
            });

使用Ocelot构建GateWay

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