@hitchy/plugin-rate-limiter

Hitchy plugin for limiting request rates

License

MIT

Installation

npm install @hitchy/plugin-rate-limiter

Usage

This plugin is providing a service for generating customized policy routing handlers suitable for limiting request rates of a hitchy-based service. Thus, you can integrate it with your service in context of policy routing configuration.

In configuration file config/policies.js you could use the plugin like this:

module.exports = function() {
	const { RateLimiter } = this.runtime.service;

	return {
		policies: {
			"POST /api": [
				RateLimiter.limitPerSecond( 10 ),
				RateLimiter.limitPerMinute( 300 ),
			],
		}
	};
};

A consuming configuration file must comply with common module pattern for gaining access on services provided by this plugin as demonstrated in second line of this example.

Currently, rate limiting works per process, only. This is not a problem in most cases for Hitchy is handling all requests in a single process due to the nature of Javascript/Node.js. It becomes an issue when running several instances of your Hitchy-based application e.g. in context of a load balancer. However, in those cases we advise to configure rate limiting at load balancer as well.

API

limitPerSecond

RateLimiter.limitPerSecond( count, { queueSize = 0, retryAfter = 10 } )

This generator creates handler accepting up to given count of requests within a rolling second. Additional requests are rejected with HTTP status code 503 suggesting to retry after given number of seconds. Either parameter must be given as number.

By defining a positive queue size, an according number of requests is deferred before rejecting.

limitPerMinute

RateLimiter.limitPerMinute( count, { retryAfter = 120 } )

This function creates handler accepting up to given count of requests within a rolling minute. Additional requests are rejected with HTTP status code 503 suggesting to retry after given number of seconds. Either parameter must be given as number.

This helper method does not support definition of a deferral queue for using it in context of a rate per minute is unusual and counterintuitive to a client expecting requests being processed in seconds at most. You might use underlying RateLimiter.limitPerTime() to have a limit per minute combined with a deferral queue.

limitPerHour

RateLimiter.limitPerHour( count, { retryAfter = 900 } )

This function creates handler accepting up to given count of requests within a rolling hour. Additional requests are rejected with HTTP status code 503 suggesting to retry after given number of seconds. Either parameter must be given as number.

This helper method does not support definition of a deferral queue for using it in context of a rate per hour is unusual and counterintuitive to a client expecting requests being processed in seconds at most. You might use underlying RateLimiter.limitPerTime() to have a limit per hour combined with a deferral queue.

limitPerTime

RateLimiter.limitPerTime( count, { timeframe = 1, queueSize = 0, retryAfter = 10 } )

This function is underlying generator used by helper functions listed before. It creates a handler accepting up to given count of requests within a rolling timeframe with its length given in seconds. Additional requests are rejected with HTTP status code 503 suggesting to retry after given number of seconds. Either parameter must be given as number.

By defining a positive queue size, an according number of requests is deferred before rejecting.