How to add rate limit (throttle) on API calling with CakePHP | prevent SPAM

Understanding API Rate Limiting

In today's digital age, APIs (Application Programming Interfaces) play a crucial role in how software applications communicate with one another. They allow different systems to exchange data seamlessly, enabling everything from social media interactions to online banking. However, as the usage of APIs grows, so does the need for effective management of their usage. This is where API rate limiting comes into play.

check example on: bitbucket: gp-barber-portal
 

 

What is API Rate Limiting?

API rate limiting is a technique used to control the amount of incoming requests to an API over a specific period. Think of it as a traffic cop for data requests. Just like how a traffic cop manages the flow of vehicles at an intersection to prevent congestion, rate limiting ensures that an API can handle requests without being overwhelmed.

Why is Rate Limiting Important?

1. Preventing Abuse: Without rate limiting, malicious users could overwhelm an API with excessive requests, causing it to crash or become unresponsive. This could lead to denial of service for legitimate users.
2. Resource Management: APIs often have limited resources, such as server bandwidth and processing power. Rate limiting helps ensure that these resources are used effectively, allowing for a smoother experience for all users.
3. Performance Consistency: By controlling the number of requests, API providers can maintain consistent performance. This means that users will experience fewer delays and outages.
4. Fair Usage: Rate limiting ensures that no single user or application can monopolize API resources. This promotes fairness among all users, allowing everyone to benefit from the available services.
 

How Does Rate Limiting Work?

Rate limiting typically functions through a set of rules defined by the API provider. Here are some common strategies:
1. Fixed Window Limiting:
In this method, a time frame (or window) is defined, and a maximum number of requests is allowed within that time. For example, an API might allow 100 requests per hour. Once the limit is reached, any further requests will be rejected until the next time window begins.
2. Sliding Window Limiting:
This approach offers more flexibility than fixed window limiting. Instead of resetting the count at the end of each time window, it calculates the number of requests based on a moving time frame. This means if a user makes requests, the system will continuously check the last hour's worth of requests, allowing for a more dynamic rate limiting process.
3. Token Bucket:
In the token bucket method, tokens are generated at a certain rate and are used to allow requests. Each request consumes a token; if no tokens are available, the request is denied. This method allows for bursts of requests, as long as tokens are available, while still enforcing a long-term limit.
4. Leaky Bucket:
Similar to the token bucket, the leaky bucket method allows requests to be processed at a steady rate. Requests "leak" out of the bucket at a fixed rate, regardless of the incoming request rate. If the bucket gets too full, incoming requests will be discarded until there's more space.
 

Implementing Rate Limiting

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For developers and organizations, implementing rate limiting can vary based on the specific needs of the API. Here are a few considerations:
* Determine Limits: Decide how many requests are reasonable based on user behavior and server capacity. This might require monitoring usage patterns over time.
* Communicate Limits: Make sure users of the API are aware of the limits in place. This can be done through documentation and error messages that inform users when they've exceeded their request limits.
* Use HTTP Headers: Many APIs return specific HTTP headers that indicate the current request usage and limits. This allows users to adjust their request patterns accordingly.
* Monitor and Adjust: Continually monitor the effectiveness of the rate limiting strategy. If the limits are too strict, legitimate users may be affected; if they're too lenient, the server might struggle under heavy load.

Challenges of Rate Limiting

While rate limiting is essential, it can come with its challenges:
* User Experience: Striking a balance between protecting the API and providing a seamless user experience can be tricky. Too stringent limits might frustrate users.
* Dynamic Usage Patterns: Some applications experience variable traffic patterns. For instance, a news website might see spikes in traffic during breaking news events. Rate limiting needs to be flexible enough to accommodate these changes.
* Global vs. Local Limits: Deciding whether to apply rate limits globally (across all users) or locally (per user) can complicate implementation. Global limits may prevent abuse but can hinder legitimate use, while local limits can lead to unfair resource allocation among users.
 

Conclusion

API rate limiting is a critical aspect of API management that helps ensure reliability, performance, and fairness. By controlling the flow of requests, it protects both the API and its users from potential disruptions. Understanding rate limiting is essential for anyone interacting with APIs, whether you're a student learning about technology, a worker integrating different systems, or an IT professional managing application performance.

As APIs continue to evolve, the strategies and technologies behind rate limiting will also grow. Staying informed about these practices will not only enhance your understanding of APIs but also prepare you for a future where API usage becomes even more integral to our daily lives.

So topic today topic I will guideline you how to do it on CakePHP framework,

create a src/Http/Exception/RateLimitExceededException.php

// huuvi168@gmail.com
<?php // src/Http/Exception/RateLimitExceededException.php
namespace App\Http\Exception;

use Cake\Http\Exception\HttpException;

class RateLimitExceededException extends HttpException
{
    protected $message = 'Rate limit exceeded. Please try again later.';
    protected $status = 429; // HTTP Status Code for Too Many Requests

    public function __construct($message = null, $status = null, \Exception $previous = null)
    {
        if ($message) {
            $this->message = $message;
        }
        if ($status) {
            $this->status = $status;
        }
        parent::__construct($this->message, $this->status, $previous);
    }
}

   

Create a middleware  src/Middleware/RateLimitMiddleware.php

  
<?php
declare(strict_types=1);

namespace App\Middleware;

use App\Http\Exception\RateLimitExceededException; 
use Cake\Http\Response;
use Cake\Http\ServerRequest; 
use Cake\ORM\TableRegistry;
use Psr\Http\Message\ResponseInterface;

class RateLimitMiddleware
{
    protected $limit = 1; // 100 Number of allowed requests (1 request in 300s)
    protected $timeFrame = 300; // 3600;  Time frame in seconds

    public function __invoke(ServerRequest $request, Response $response, callable $next)
    {
        $ip = $request->clientIp();
        $obj_RateLimitings = TableRegistry::getTableLocator()->get('RateLimitings');
        try {
            // Check the number of requests made by the IP
            $record = $obj_RateLimitings->find()
                ->where(['ip' => $ip])
                ->first();

            if ($record && $record->request_count >= $this->limit) { 
                throw new RateLimitExceededException( );    // Use custom exception
            }

            // Update or create the record
            $this->updateRateLimit($ip);

            return $next($request, $response);
        } catch (RateLimitExceededException $e) {
                // Create a custom response for the exception
            return $this->handleRateLimitException($response, $e);
        }
    }

    protected function handleRateLimitException(Response $response, RateLimitExceededException $e): ResponseInterface
    {
        return $response->withStatus($e->getCode()) // Use the custom exception code
                        ->withType('application/json')
                        ->withStringBody(json_encode([ 
                            'status' => $e->getCode(),
                            'message' => $e->getMessage(), 
                        ]));
    }
 

    protected function updateRateLimit($ip)
    {
        // Logic to update or create a record
        // Increment request_count and reset on expiration
        $obj_RateLimitings = TableRegistry::getTableLocator()->get('RateLimitings');
        $record = $obj_RateLimitings->find()->where(['ip' => $ip])->first();

        if ($record) {
            // Check if the time frame has elapsed
            if (strtotime($record->last_request->format('Y-m-d H:i:s')) + $this->timeFrame < time()) {
                $record->request_count = 1; // Reset count
            } else {
                $record->request_count++; // Increment count
            }
            $record->last_request = date('Y-m-d H:i:s');
            $obj_RateLimitings->save($record);

        } else {
            // Create new record
            $obj_RateLimitings->save($obj_RateLimitings->newEntity(['ip' => $ip, 'request_count' => 1]));
        }
    }
}

   

on src/Application.php

public function middleware(MiddlewareQueue $middlewareQueue): MiddlewareQueue {
 		$middlewareQueue
            // Catch any exceptions in the lower layers,
            // and make an error page/response
            ->add(new ErrorHandlerMiddleware(Configure::read('Error')))

            // Handle plugin/theme assets like CakePHP normally does.
            ->add(new AssetMiddleware([
                'cacheTime' => Configure::read('Asset.cacheTime'),
            ]))

             …            
            // Parse various types of encoded request bodies so that they are
            // available as array through $request->getData()
            // https://book.cakephp.org/4/en/controllers/middleware.html#body-parser-middleware
            ->add(new BodyParserMiddleware())

            ->add(new RateLimitMiddleware());	// add this line
}
   

Thanks for reading. 

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