限流，可以网络的基础设施进行配置实现，也可以在网关的地方进行限流，但服务本身的限流也不可或缺，因为当多副本时，一个副本故障，流量对于其他副本来说会提高，如果超过其承受请求量的范围，会引起服务连续崩塌，所以单服务本身最好也是要实现限流的。

在asp.net core项目中，可以引入AspNetCoreRateLimit进行限流处理。

可以通过如下方式引入NuGet包

Install-Package AspNetCoreRateLimit

Client限流

using AspNetCoreRateLimit;

var builder = WebApplication.CreateBuilder(args);
// 注入内存缓存服务
builder.Services.AddMemoryCache();
//加载ClientRateLimiting配置文件
builder.Services.Configure<ClientRateLimitOptions>(builder.Configuration.GetSection("ClientRateLimiting"));
//加载ClientRateLimitPolicies配置文件
builder.Services.Configure<ClientRateLimitPolicies>(builder.Configuration.GetSection("ClientRateLimitPolicies"));

// 注入限流内存缓存服务
builder.Services.AddInMemoryRateLimiting();
// 注入限流配置文件服务
builder.Services.AddSingleton<IRateLimitConfiguration, RateLimitConfiguration>();

var app = builder.Build();

//启用ClientRateLimitPolicies
var clientPolicyStore = app.Services.GetRequiredService<IClientPolicyStore>();
await clientPolicyStore.SeedAsync();
//使用Client限流中间件
app.UseClientRateLimiting();

app.MapGet("/test00", () =>
{
    return "get test00 ok";
});

app.MapGet("/test01", () =>
{
    return "get test01 ok";
});
app.MapGet("/test02", () =>
{
    return "get test02 ok";
});
app.MapPost("/test02", () =>
{
    return "post test02 ok";
});

app.Run();

appsetings.json

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*",
  "ClientRateLimiting": {
    "EnableEndpointRateLimiting": false,
    "StackBlockedRequests": false,
    "ClientIdHeader": "X-ClientId",
    "HttpStatusCode": 429,
    "EndpointWhitelist": [ "get:/test00", "*:/test01" ],
    "ClientWhitelist": [ "dev-id-1", "dev-id-2" ],
    "GeneralRules": [
      {
        "Endpoint": "*",
        "Period": "5s",
        "Limit": 2
      },
      {
        "Endpoint": "*",
        "Period": "10s",
        "Limit": 3
      }      
    ]
  },
   "ClientRateLimitPolicies": {
    "ClientRules": [
      {
        "ClientId": "client-id-1",
        "Rules": [
          {
            "Endpoint": "*",
            "Period": "5s",
            "Limit": 1
          },
          {
            "Endpoint": "*",
            "Period": "15m",
            "Limit": 200
          }
        ]
      },
      {
        "ClientId": "client-id-2",
        "Rules": [
          {
            "Endpoint": "*",
            "Period": "1s",
            "Limit": 5
          },
          {
            "Endpoint": "*",
            "Period": "15m",
            "Limit": 150
          },
          {
            "Endpoint": "*",
            "Period": "12h",
            "Limit": 500
          }
        ]
      }
    ]
  }
}

配置说明：

EnableEndpointRateLimiting为false全部请求总次数超过阈值，即限流，EnableEndpointRateLimiting为true时，各个请求单次超过阈值即限流StackBlockedRequests为false时，如果前5s请求了2个成功，1个失败，那第6s后还可以请求一个成功，如果这StackBlockedRequests为true时，那第6s的请求是不能成功的，也就是带不带拒绝的请求

{
        "Endpoint": "*",
        "Period": "5s",
        "Limit": 2
      },
      {
        "Endpoint": "*",
        "Period": "10s",
        "Limit": 3
      },

ClientIdHeader指定可以通过Header键为X-ClientId处理限流黑白名单ClientWhitelist值为dev-id-1，dev-id-2，指Header里X-ClientId只要是其中的值 ，就放行EndpointWhitelist不参与限流的终节点HttpStatusCode限流后返回的状态码

GeneralRules通用限流规则

ClientRateLimitPolicies 配置是专门为了对不同的X-ClientId进行不同的限流配置，这样可以有区别的来分配流程，而不是一概而论，可以说是ClientId的灰名单，有限流的访问

不但可以通过ClientID限流，还可以是客户请示Ip来限流，配置雷同。

IP限流

using AspNetCoreRateLimit;

var builder = WebApplication.CreateBuilder(args);
// 注入内存缓存服务
builder.Services.AddMemoryCache();


//加载IPRateLimiting配置文件
builder.Services.Configure<IpRateLimitOptions>(builder.Configuration.GetSection("IpRateLimiting"));

//加载IPRateLimitPolicies配置文件
builder.Services.Configure<IpRateLimitPolicies>(builder.Configuration.GetSection("IpRateLimitPolicies"));

// 注入限流内存缓存服务
builder.Services.AddInMemoryRateLimiting();
// 注入限流配置文件服务
builder.Services.AddSingleton<IRateLimitConfiguration, RateLimitConfiguration>();

var app = builder.Build();
//启用IPRateLimitPolicies
var ipPolicyStore = app.Services.GetRequiredService<IIpPolicyStore>();
await ipPolicyStore.SeedAsync();
//使用Ip限流中间件
app.UseIpRateLimiting();

app.MapGet("/test00", () =>
{
    return "get test00 ok";
});

app.MapGet("/test01", () =>
{
    return "get test01 ok";
});

app.MapGet("/test02", () =>
{
    return "get test02 ok";
});
app.MapPost("/test02", () =>
{
    return "post test02 ok";
});
app.MapGet("/test03", () =>
{
    return "get test01 ok";
});
app.Run();

appsettings.json

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*",
  "IpRateLimiting": {
    "EnableEndpointRateLimiting": false,
    "StackBlockedRequests": false,
    "RealIpHeader": "X-Real-IP",
    "IpWhitelist": [ "127.0.0.1"],
    "ClientIdHeader": "X-ClientId",
    "HttpStatusCode": 429,
    "EndpointWhitelist": [ "get:/test00", "*:/test01" ],
    "ClientWhitelist": [ "dev-id-1", "dev-id-2" ],
    "GeneralRules": [
      {
        "Endpoint": "*",
        "Period": "5s",
        "Limit": 2
      },
      {
        "Endpoint": "*",
        "Period": "10s",
        "Limit": 3
      }     
    ]
  },
  "IpRateLimitPolicies": {
    "IpRules": [
      {
        "Ip": "127.0.0.2",
        "Rules": [
          {
            "Endpoint": "*",
            "Period": "4s",
            "Limit": 1
          },
          {
            "Endpoint": "*",
            "Period": "15m",
            "Limit": 200
          }
        ]
      }     
    ]
  }
}

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.NET6之MiniAPI(二十一)：限流_配置文件