CODEWITHSUNDEEP
.net-coreazure-functions
Jussi Palo
Jussi Palo

Reputation: 955

.NET 7 Rate Limiting in Azure Function

Is there a way to use .NET 7 Rate Limiting on Azure Function v4 (dotnet-isolated) HttpTrigger?

I've added RateLimiter in my ConfigureServices like this:

var builder = new HostBuilder()
    .ConfigureFunctionsWorkerDefaults()
    .ConfigureServices(s =>
    {
        // ...
        
        s.AddRateLimiter(_ =>
        {
            _.AddPolicy("myfunction", httpContext =>
                RateLimitPartition.GetSlidingWindowLimiter(httpContext.Request.Headers["X-Forwarded-For"],
                _ => new SlidingWindowRateLimiterOptions
                {
                    AutoReplenishment = true,
                    PermitLimit = 1,
                    Window = TimeSpan.FromSeconds(5)
                }));
        });
    })
    .Build();

and

 [Function("myfunction")]
 [EnableRateLimiting("myfunction")]
 public async Task<IActionResult> MyFunction(
     [HttpTrigger(AuthorizationLevel.Function, "post", Route = null)] HttpRequestData req)
 { // ...
 }

I'm pretty sure it shouldn't even work like this, but just to give an example of the scenario. My architecture is Azure Static Web App --> API Management (NOTE! consumption plan) --> Azure Function, and I can get the valid client IP from the X-Forwarded-For header in the Azure Function, but

So, is it possible to apply the rate limiting policy to a Azure Function on a function level?

Thanks!

Upvotes: 0

Views: 1601

Answers (2)

scale_tone
scale_tone

Reputation: 312

Just ported ThrottlingTroll to Azure Functions (.NET 7 Isolated).

Works as an Azure Functions Middleware.

Supports

Configurable via host.json, programmatically or dynamically (by periodically reloading rate limits from whatever external config store without restarting the service).

Stores counters in memory or in a distributed cache.

Install from NuGet:

dotnet add package ThrottlingTroll.AzureFunctions

and then configure like this:

builder.ConfigureFunctionsWorkerDefaults((hostBuilderContext, workerAppBuilder) => {

    workerAppBuilder.UseThrottlingTroll(hostBuilderContext, options =>
    {
        options.Config = new ThrottlingTrollConfig
        {
            Rules = new[]
            {
                new ThrottlingTrollRule
                {
                    UriPattern = "myfunction",

                    LimitMethod = new FixedWindowRateLimitMethod
                    {
                        PermitLimit = 1,
                        IntervalInSeconds = 5
                    },

                    // Identifying clients by their IP addresses
                    IdentityIdExtractor = request =>
                    {
                        request.Headers.TryGetValue("x-forwarded-for", out var clientIpAddress);
                        return clientIpAddress;
                    }
                }
            }
        };
    });
});

Upvotes: 4

Pravallika KV
Pravallika KV

Reputation: 8694

As @Silent mentioned, you can use rate-limiting policy in Azure APIM Consumption Plan.

You can import multiple Function APIS to the Azure APIM Service and can add the Rate-limiting policy to each API Level.
enter image description here

I have consumption plan APIM, and I’d very much like to have a IP based rate limiter instead of API based, like it is with consumption plan APIM

I understand that you need to limit the number of requests per IP basis. If yes and this is the scenario, we have “IP address throttling” concept to limit the requests/API Calls from the IP address as mentioned in this MS Doc of Custom key-based throttling in Rate-limiting policy.

Note:

Yes, the rate-limit-by-key is not available in APIM Consumption Plan.

Upvotes: 1

Related Questions