关于“ASP.NET Core使用固定窗口限流”的完整攻略,我会给你一个详细的解释:
什么是固定窗口限流
固定窗口限流是一种常用的限流算法,它将时间分成固定的窗口,每个窗口内的请求次数不能超过一定的阈值。举个例子:如果我们将时间分成1秒钟的窗口,设置每个窗口内最多只能处理10个请求,那么当某个窗口内的请求数超过10个时,则该窗口内的请求需要被限制。
如何使用固定窗口限流
在ASP.NET Core中,我们可以通过使用Middleware来实现固定窗口限流。具体步骤如下:
- 安装AspNetCoreRateLimit NuGet包
dotnet add package AspNetCoreRateLimit
- 在Startup.cs文件中注册限流中间件
public void ConfigureServices(IServiceCollection services)
{
// 注册限流服务
services.AddMemoryCache();
services.Configure<IpRateLimitOptions>(Configuration.GetSection("IpRateLimiting"));
services.Configure<IpRateLimitPolicies>(Configuration.GetSection("IpRateLimitPolicies"));
services.AddSingleton<IIpPolicyStore, MemoryCacheIpPolicyStore>();
services.AddSingleton<IRateLimitCounterStore, MemoryCacheRateLimitCounterStore>();
services.AddSingleton<IRateLimitConfiguration, RateLimitConfiguration>();
}
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
app.UseIpRateLimiting();
app.UseRouting();
app.UseEndpoints(endpoints =>
{
endpoints.MapControllers();
});
}
- 在appsettings.json文件中配置限流策略
"IpRateLimiting": {
"Enabled": true,
"IpWhitelist": [],
"IpAddressHeaders": [],
"GeneralRules": [
{
"Endpoint": "*",
"Period": "5m",
"Limit": 1000
}
],
"EndpointRules": []
},
"IpRateLimitPolicies": {
"Quick": {
"Rules": [
{
"Endpoint": "*",
"Period": "1m",
"Limit": 30
}
]
},
"AbitSlow": {
"Rules": [
{
"Endpoint": "*",
"Period": "5m",
"Limit": 150
}
]
}
}
上述配置中,"GeneralRules"为全局限流策略,"EndpointRules"为针对具体Endpoint的限流策略。"IpRateLimitPolicies"定义了不同的限流策略,可以根据自己的需要进行配置。
- 使用限流特性标记Controller或Action方法
[ApiController]
[Route("[controller]")]
[EnableRateLimiting("AbitSlow")]
public class WeatherForecastController : ControllerBase
{
// ...
}
通过使用EnableRateLimiting特性,将创建一个名为"AbitSlow"的限流策略,并应用于该控制器中的所有Action方法上。
示例说明
这里给出两个简单的示例:
示例1
首先创建一个名为"限流演示"的ASP.NET Core Web应用程序,在WeatherForecastController中添加代码:
[ApiController]
[Route("[controller]")]
[EnableRateLimiting("Quick")]
public class WeatherForecastController : ControllerBase
{
private static readonly string[] Summaries = new[]
{
"Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
};
private readonly ILogger<WeatherForecastController> _logger;
public WeatherForecastController(ILogger<WeatherForecastController> logger)
{
_logger = logger;
}
[HttpGet]
public IEnumerable<WeatherForecast> Get()
{
var rng = new Random();
return Enumerable.Range(1, 5).Select(index => new WeatherForecast
{
Date = DateTime.Now.AddDays(index),
TemperatureC = rng.Next(-20, 55),
Summary = Summaries[rng.Next(Summaries.Length)]
})
.ToArray();
}
[HttpGet("{id}")]
public WeatherForecast Get(int id)
{
var rng = new Random();
return new WeatherForecast
{
Date = DateTime.Now.AddDays(id),
TemperatureC = rng.Next(-20, 55),
Summary = Summaries[rng.Next(Summaries.Length)]
};
}
}
在appsettings.json中添加以下配置:
"IpRateLimitPolicies": {
"Quick": {
"Rules": [
{
"Endpoint": "*",
"Period": "1m",
"Limit": 5
}
]
}
}
启动应用程序并使用浏览器或Postman发送多个请求,可以看到在1分钟内只能处理5个请求,超出该限制的请求将被拦截。
示例2
接下来创建一个控制器用于测试针对具体Endpoint的限流策略:
[ApiController]
[Route("[controller]")]
public class TestController : ControllerBase
{
[HttpGet("1")]
[EnableRateLimiting("Quick")]
public ActionResult<string> Test1()
{
return "Test1";
}
[HttpGet("2")]
[EnableRateLimiting("AbitSlow")]
public ActionResult<string> Test2()
{
return "Test2";
}
}
在appsettings.json中添加以下配置:
"IpRateLimitPolicies": {
"Quick": {
"Rules": [
{
"Endpoint": "/test/1",
"Period": "1m",
"Limit": 2
}
]
},
"AbitSlow": {
"Rules": [
{
"Endpoint": "/test/2",
"Period": "10s",
"Limit": 1
}
]
}
}
启动应用程序并发送多个请求,观察控制台输出,可以看到针对/Test/1的Endpoint在1分钟内只能处理2个请求,而针对/Test/2的Endpoint在10秒内只能处理1个请求。如果请求超过了限制,将会返回429状态码。
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