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20001或者 20002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();
                }
            });

 注：上述代码注册指适用于 Hosting方式  ，如果你用的IIS做寄宿，

 var addessess = features.Get<IServerAddressesFeature>().Addresses.Select(url => new Uri(url));

 获取到的地址不是你期待的地址，它是本地 127.0.0.1：随机端口 ，会导致健康检查服务注册了之后无法进行健康检查

可以配置下不同的启动方式来设置

  applicationLifetime.ApplicationStarted.Register(() =>
            {


                if (userappsetting.Value.IsIISHost)
                {
                    #region IIS 寄宿方式
                    var httpcheck = new AgentServiceCheck()
                    {
                        DeregisterCriticalServiceAfter = TimeSpan.FromMinutes(userappsetting.Value.DeregisterCriticalServiceAfter),
                        Interval = TimeSpan.FromSeconds(userappsetting.Value.Interval),
                        HTTP = new Uri(new Uri(userappsetting.Value.CurrentIISUrl), userappsetting.Value.MatchPath).OriginalString

                    };
                    //这里可以注入配置
                    var agentReg = new AgentServiceRegistration()
                    {
                        ID = $"{userappsetting.Value.ServiceName}_{userappsetting.Value.CurrentIISUrl}_{userappsetting.Value.CurrentIISPort}",
                        Check = httpcheck,
                        Name = userappsetting.Value.ServiceName,
                        Address = userappsetting.Value.CurrentIISUrl,
                        Port = userappsetting.Value.CurrentIISPort

                    };
                    client.Agent.ServiceRegister(agentReg).ConfigureAwait(false);
                    #endregion
                }
                else
                {
                    #region 服务注册健康检查 Hosting寄宿
                    var addessess = app.ServerFeatures.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, userappsetting.Value.MatchPath).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);
                    }
                    #endregion

                }


            });
            applicationLifetime.ApplicationStopped.Register(() =>
            {
                if (userappsetting.Value.IsIISHost)
                {
                    client.Agent.ServiceDeregister($"{userappsetting.Value.ServiceName}_{userappsetting.Value.CurrentIISUrl}_{userappsetting.Value.CurrentIISPort}").GetAwaiter().GetResult();
                }
                else
                {

                    var addessess = app.ServerFeatures.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();
                    }
                }

            });
            return applicationLifetime;