dotnet consul 与 ocelot

创建

重新创建一个项目
dotnet new webapi --name gateway

安装ocelot
dotnet add package Ocelot --version 15.0.6

在startup.cs的Configure类中注释其它代码，然后添加

app.UseOcelot();

在startup.cs的ConfigureServices类中注释其它代码，然后添加

services.AddOcelot();

在Program.cs的CreateHostBuilder类中修改代码如下：

Host.CreateDefaultBuilder(args)
.ConfigureAppConfiguration(conf =>
{
    conf.AddJsonFile("configuration.json", optional: false, reloadOnChange: true);
})
.ConfigureWebHostDefaults(webBuilder =>
{
    webBuilder.UseStartup<Startup>();
});

然后在根目录下添加configuration.json文件

{
 "ReRoutes": [
   {
     "DownstreamPathTemplate": "/api/{url}",
     "DownstreamScheme": "http",
     "DownstreamHostAndPorts": [
       {
         "Host": "39.108.54.23",
         "Port": 8081 
       } 
       ,
       {
         "Host": "39.108.54.23",
         "Port": 8082 
       },
       {
         "Host": "39.108.54.23",
         "Port": 8083 
       }
     ],
     "UpstreamPathTemplate": "/up/{url}", //如url冲突可加Priority决定
     "UpstreamHttpMethod": [ "Get", "Post" ],  
     "LoadBalancerOptions": {
       "Type":"RoundRobin" //轮询 //"LeastConnection" //最小连接数 "NoLoadBalance" //不负载均衡  //"CookieStickySessions" //会话粘滞
     }
     //"LoadBalancerOptions": {
     //  "Type": "CookieStickySessions",
     //  "Key": "ASP.NET_SessionId",
     //  "Expiry": 1800000
     //}
   }
 ]
}

运行

运行项目，使用上游设置的url访问 https://localhost:5001/up/value/get ，刷新可以观察到端口有轮询切换
上游的url：/up/value/get 对应下游url：/api/value/get

如把8081端口进程杀掉，刷新页面，当轮询到8081端口时会访问不了，再刷新又访问到（已切换到8082端口）

鉴于以上这种情况，可结合consul使用

安装 Ocelot.Provider.Consul
dotnet add package Ocelot.Provider.Consul --version 15.0.6

在startip.cs文件中修改

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

configuration.json文件修改如下：

"ReRoutes":[
    {
        "UseServiceDiscovery":true,
        "DownstreamPathTemplate": "/api/{url}",
        "DownstreamScheme": "http",
        "ServiceName":"xing",
        "LoadBalancerOptions": {
            "Type":"RoundRobin" 
        },
        "UpstreamPathTemplate": "/up/{url}",
        "UpstreamHttpMethod": [ "Get", "Post" ],
        "ReRoutesCaseSensitive":false
    }
],
"GlobalConfiguration":{
    "ServiceDiscoveryProvider":{
        "Host":"localhost",
        "Port":8500,
        "ConfigurationKey":"ocelot_key"，
        "Type": "Consul" // 提供服务发现，每次都请求
    }
     //"ServiceDiscoveryProvider": {
      //  "Host": "localhost",
      //  "Port": 8500,
      //  "Type": "PollConsul", 
      //  "PollingInterval": 1000 //间隔1秒一次啊
      //  //"Token": "footoken"//ACL
      // }
    
}

然后运行下面命令启动，这可解决上面出现的问题（在本地运行没问题，在linux上运行报错：下图）

dotnet gateway.dll --urls="http://*:9000" --ip="127.0.0.1" --port=9000

缓存

安装
dotnet add package Ocelot.Cache.CacheManager --version 14.1.0
在startup.cs文件configureServices添加

.AddCacheManager(x => {x.WithDictionaryHandle();})      // 默认字典存储

还需引用using Ocelot.Cache.CacheManager;

修改configuration.json文件

{
 "ReRoutes": [
   {
     "DownstreamPathTemplate": "/api/{url}", 
     "DownstreamScheme": "http",
     "UpstreamPathTemplate": "/up/{url}", 
     "UpstreamHttpMethod": [ "Get", "Post" ],
     "UseServiceDiscovery": true,
     "ServiceName": "xing", 
     "LoadBalancerOptions": {
       "Type": "RoundRobin" 
     },
     "FileCacheOptions": {
       "TtlSeconds": 15,
       "Region": "UserCache" 
     }
   }
 ],
 "GlobalConfiguration": {
   "BaseUrl": "http://127.0.0.1:9000", 
   "ServiceDiscoveryProvider": {
     "Host": "localhost",
     "Port": 8500,
     "Type": "Consul" 
   }
   //"ServiceDiscoveryProvider": {
   //  "Host": "localhost",
   //  "Port": 8500,
   //  "Type": "PollConsul", 
   //  "PollingInterval": 1000 
   //  //"Token": "footoken"
   //}
 }
}

超时、熔断、限流、降级、聚合请求

安装
dotnet add package Ocelot.Provider.Polly --version 15.0.6

熔断、限流

配置如下

{
 "ReRoutes": [
   {
     "DownstreamPathTemplate": "/api/{url}", 
     "DownstreamScheme": "http",
     "UpstreamPathTemplate": "/up/{url}", 
     "UpstreamHttpMethod": [ "Get", "Post" ],
     "UseServiceDiscovery": true,
     "ServiceName": "xing", 
     "LoadBalancerOptions": {
       "Type": "RoundRobin" 
     },
      // 限流
    //  "RateLimitOptions": {
    //    "ClientWhitelist": [ "one", "two" ],  // 白名单
    //    "EnableRateLimiting": true,
    //    "Period": "5m", //1s, 5m, 1h, 1d
    //    "PeriodTimespan": 30,    // 几秒后可重试
    //    "Limit": 5  // 最大请求数
    //  }
     "QoSOptions": {
      "ExceptionsAllowedBeforeBreaking": 3, //允许几个异常
      "DurationOfBreak": 10000, // 熔断时间，ms
      "TimeoutValue": 4000 //请求超时时间
     }
   }
 ],
 "GlobalConfiguration": {
   "BaseUrl": "http://127.0.0.1:9000", 
   "ServiceDiscoveryProvider": {
     "Host": "localhost",
     "Port": 8500,
     "Type": "Consul" 
   },
   "RateLimitOptions": {
     "QuotaExceededMessage": "Too many requests, maybe later?", 
     "HttpStatusCode": 440 //返回状态码 
   }
 }
}

请求聚合

配置如下

{
 "ReRoutes": [
   {
     "DownstreamPathTemplate": "/api/value/get",
     "DownstreamScheme": "http",
     "DownstreamHostAndPorts": [
       {
         "Host": "localhost",
         "Port": 8081 
       } 
     ],
     "UpstreamPathTemplate": "/one/value/get",
     "UpstreamHttpMethod": [ "Get", "Post" ],
     "key": "one"
   },
   {
     "DownstreamPathTemplate": "/api/value/get", 
     "DownstreamScheme": "http",
     "DownstreamHostAndPorts": [
       {
         "Host": "localhost",
         "Port": 8082 
       }
     ],
     "UpstreamPathTemplate": "/two/value/get", 
     "UpstreamHttpMethod": [ "Get", "Post" ],
     "key": "two"
   },
   {
     "DownstreamPathTemplate": "/api/value/get", 
     "DownstreamScheme": "http",
     "DownstreamHostAndPorts": [
       {
         "Host": "localhost",
         "Port": 8083 
       }
     ],
     "UpstreamPathTemplate": "/three/value/get", 
     "UpstreamHttpMethod": [ "Get", "Post" ],
     "key": "three"
   }
 ],
 "Aggregates": [
   {
     "ReRouteKeys": [
       "one",
       "two",
       "three"
     ],
     "UpstreamPathTemplate": "/UserAggregator",
     //"Aggregator": "UserAggregator"
   }
 ]
}