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}]}     ]}
}