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How to design an API Rate Limiter?

Anjali Sharma answered on January 15, 2023 Popularity 7/10 Helpfulness 1/10

answer How to design an API Rate Limiter?

How to design an API Rate Limiter?

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Using Rate Limiter we can enforce policies as below:

A maximum of 20 accounts are allowed to be created per day from a unique source IP address. This helps minimizing spams or malicious accounts creation, and Denial of Service (DoS) and Distributed Denial of Service (DDoS).

Devices are allowed 5 failed credit card transactions per day.

Users may only send 1 message per day with risky keywords.

public class RateLimitInterceptor implements HandlerInterceptor {

    private PricingPlanService pricingPlanService;

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) 
      throws Exception {
        String apiKey = request.getHeader("X-api-key");
        if (apiKey == null || apiKey.isEmpty()) {
            response.sendError(HttpStatus.BAD_REQUEST.value(), "Missing Header: X-api-key");
            return false;
        }

        Bucket tokenBucket = pricingPlanService.resolveBucket(apiKey);
        ConsumptionProbe probe = tokenBucket.tryConsumeAndReturnRemaining(1);
        if (probe.isConsumed()) {
            response.addHeader("X-Rate-Limit-Remaining", String.valueOf(probe.getRemainingTokens()));
            return true;
        } else {
            long waitForRefill = probe.getNanosToWaitForRefill() / 1_000_000_000;
            response.addHeader("X-Rate-Limit-Retry-After-Seconds", String.valueOf(waitForRefill));
            response.sendError(HttpStatus.TOO_MANY_REQUESTS.value(),
              "You have exhausted your API Request Quota"); 
            return false;
        }
    }
}

https://blog.tryexponent.com/rate-limiter-system-design/

Popularity 7/10 Helpfulness 1/10 Language java

Source: Grepper

Tags: java rate

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Contributed on Jan 15 2023

Anjali Sharma

0 Answers Avg Quality 2/10

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