rate-limiter-flexible
Advanced tools
Flexible API rate limiter backed by Redis for distributed node.js applications
The rate-limiter-flexible npm package is a powerful and flexible rate limiting library for Node.js. It supports various backends like Redis, MongoDB, and in-memory storage, making it suitable for distributed systems. It helps in controlling the rate of requests to APIs, preventing abuse, and ensuring fair usage.
Basic Rate Limiting
This feature allows you to set up basic rate limiting using in-memory storage. The example limits a user to 5 requests per second.
const { RateLimiterMemory } = require('rate-limiter-flexible');
const rateLimiter = new RateLimiterMemory({
points: 5, // 5 points
duration: 1, // Per second
});
rateLimiter.consume('user-key')
.then(() => {
// Allowed
})
.catch(() => {
// Blocked
});Rate Limiting with Redis
This feature demonstrates how to use Redis as a backend for rate limiting. The example limits a user to 10 requests per minute.
const { RateLimiterRedis } = require('rate-limiter-flexible');
const Redis = require('ioredis');
const redisClient = new Redis();
const rateLimiter = new RateLimiterRedis({
storeClient: redisClient,
points: 10, // 10 points
duration: 60, // Per minute
});
rateLimiter.consume('user-key')
.then(() => {
// Allowed
})
.catch(() => {
// Blocked
});Rate Limiting with MongoDB
This feature shows how to use MongoDB as a backend for rate limiting. The example limits a user to 5 requests per minute.
const { RateLimiterMongo } = require('rate-limiter-flexible');
const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost:27017/rate-limiter', { useNewUrlParser: true, useUnifiedTopology: true });
const rateLimiter = new RateLimiterMongo({
storeClient: mongoose.connection,
points: 5, // 5 points
duration: 60, // Per minute
});
rateLimiter.consume('user-key')
.then(() => {
// Allowed
})
.catch(() => {
// Blocked
});Rate Limiting with Bursts
This feature allows for burst handling by blocking the user for a specified duration if they exceed the rate limit. The example blocks a user for 10 seconds if they exceed 10 requests per second.
const { RateLimiterMemory } = require('rate-limiter-flexible');
const rateLimiter = new RateLimiterMemory({
points: 10, // 10 points
duration: 1, // Per second
blockDuration: 10, // Block for 10 seconds if consumed more than points
});
rateLimiter.consume('user-key')
.then(() => {
// Allowed
})
.catch(() => {
// Blocked
});express-rate-limit is a basic rate-limiting middleware for Express applications. It is simpler and less flexible compared to rate-limiter-flexible, but it is easier to set up for basic use cases.
rate-limiter is another rate limiting library for Node.js. It is less feature-rich compared to rate-limiter-flexible and does not support as many backends, but it is straightforward to use for simple rate limiting needs.
bottleneck is a powerful rate limiting and job scheduling library for Node.js. It offers more advanced features like priority queues and job scheduling, making it more suitable for complex use cases compared to rate-limiter-flexible.
Flexible rate limiter and anti-DDoS protector works in process Memory, Cluster or Redis allows to control requests rate in single process or distributed environment.
It uses fixed window as it is much faster than rolling window. See comparative benchmarks with other libraries here
Advantages:
insuranceLimiter set uppenalty and reward methods to change limits on some results of an actionEndpoint is simple Express 4.x route launched in node:latest and redis:alpine Docker containers by PM2 with 4 workers
By bombardier -c 1000 -l -d 10s -r 2500 -t 5s http://127.0.0.1:3000/pricing
Test with 1000 concurrent requests with maximum 2500 requests per sec during 10 seconds
Statistics Avg Stdev Max
Reqs/sec 1994.83 439.72 5377.15
Latency 6.09ms 5.06ms 88.44ms
Latency Distribution
50% 4.98ms
75% 6.65ms
90% 9.33ms
95% 13.65ms
99% 34.27ms
HTTP codes:
1xx - 0, 2xx - 59997, 3xx - 0, 4xx - 0, 5xx - 0
Note: Performance will be much better on real servers, as for this benchmark everything was launched on one machine
npm i rate-limiter-flexible
It supports both redis and ioredis clients.
Redis client must be created with offline queue switched off.
const redis = require('redis');
const redisClient = redis.createClient({ enable_offline_queue: false });
const Redis = require('ioredis');
const redisClient = new Redis({
options: {
enableOfflineQueue: false
}
});
const { RateLimiterRedis, RateLimiterMemory } = require('rate-limiter-flexible');
// It is recommended to process Redis errors and setup some reconnection strategy
redisClient.on('error', (err) => {
});
const opts = {
redis: redisClient,
keyPrefix: 'rlflx', // useful for multiple limiters
points: 5, // Number of points
duration: 5, // Per second(s)
execEvenly: false,
// Redis specific
blockOnPointsConsumed: 10, // If 10 points consumed in current duration
blockDuration: 30, // block for 30 seconds in current process memory
// It will be used only on Redis error as insurance
// Can be any implemented limiter like RateLimiterMemory or RateLimiterRedis extended from RateLimiterAbstract
insuranceLimiter: new RateLimiterMemory(
{
points: 1, // 1 is fair if you have 5 workers and 1 cluster
duration: 5,
execEvenly: false,
})
};
const rateLimiterRedis = new RateLimiterRedis(opts);
rateLimiterRedis.consume(remoteAddress)
.then((rateLimiterRes) => {
// ... Some app logic here ...
// Depending on results it allows to fine
rateLimiterRedis.penalty(remoteAddress, 3)
.then((rateLimiterRes) => {});
// or rise number of points for current duration
rateLimiterRedis.reward(remoteAddress, 2)
.then((rateLimiterRes) => {});
})
.catch((rejRes) => {
if (rejRes instanceof Error) {
// Some Redis error
// Never happen if `insuranceLimiter` set up
// Decide what to do with it in other case
} else {
// Can't consume
// If there is no error, rateLimiterRedis promise rejected with number of ms before next request allowed
const secs = Math.round(rejRes.msBeforeNext / 1000) || 1;
res.set('Retry-After', String(secs));
res.status(429).send('Too Many Requests');
}
});
Note: it doesn't work with PM2 yet
RateLimiterCluster performs limiting using IPC. Each request is sent to master process, which handles all the limits, then master send results back to worker.
See RateLimiterCluster benchmark and detailed description here
const cluster = require('cluster');
const numCPUs = require('os').cpus().length;
const { RateLimiterClusterMaster, RateLimiterCluster } = require('rate-limiter-flexible');
if (cluster.isMaster) {
// Doesn't require any options, it is only storage and messages handler
new RateLimiterClusterMaster();
for (let i = 0; i < numCPUs; i++) {
cluster.fork();
}
} else {
const rateLimiter = new RateLimiterCluster({
keyPrefix: 'myclusterlimiter', // Must be unique for each limiter
points: 100,
duration: 1,
timeoutMs: 3000 // Promise is rejected, if master doesn't answer for 3 secs
});
// Usage is the same as for RateLimiterRedis
}
It manages limits in current process memory, so keep it in mind when use it in cluster
const rateLimiter = new RateLimiterMemory( // It will be used only on Redis error as insurance
{
keyPrefix: 'rlflx',
points: 1, // 1 is fair if you have 5 workers and 1 cluster, all workers will limit it to 5 in sum
duration: 5,
execEvenly: false,
});
// Usage is the same as for RateLimiterRedis
// Except: it never rejects Promise with Error
keyPrefix Default: 'rlflx'' If you need to create several limiters for different purpose
points Default: 4 Maximum number of points can be consumed over duration
duration Default: 1 Number of seconds before points are reset
execEvenly Default: false Delay action to be executed evenly over duration
First action in duration is executed without delay.
All next allowed actions in current duration are delayed by formula msBeforeDurationEnd / (remainingPoints + 2)
It allows to cut off load peaks.
Note: it isn't recommended to use it for long duration, as it may delay action for too long
blockOnPointsConsumed Default: 0 Against DDoS attacks. Blocked key isn't checked by requesting Redis.
Blocking works in current process memory.
Redis is quite fast, however, it may be significantly slowed down on dozens of thousands requests.
blockDuration Default: 0 Block key for blockDuration seconds,
if blockOnPointsConsumed or more points are consumed
insuranceLimiter Default: undefined Instance of RateLimiterAbstract extended object to store limits,
when Redis comes up with any error.
Additional RateLimiterRedis or RateLimiterMemory can be used as insurance.
Be careful when use RateLimiterMemory in cluster or in distributed app.
It may result to floating number of allowed actions.
If an action with a same key is launched on one worker several times in sequence,
limiter will reach out of points soon.
Omit it if you want strictly use Redis and deal with errors from it
timeoutMs Default: 5000 Timeout for communication between worker and master over IPC.
If master doesn't response in time, promise is rejected with ErrorBoth Promise resolve and reject returns object of RateLimiterRes class if there is no any error.
Object attributes:
RateLimiterRes = {
msBeforeNext: 250, // Number of milliseconds before next action can be done
remainingPoints: 0 // Number of remaining points in current duration
}
Returns Promise, which:
RateLimiterRes when point(s) is consumed, so action can be doneinsuranceLimiter isn't setup: rejected when some Redis error happened, where reject reason rejRes is Error objecttimeoutMs exceeded, where reject reason rejRes is Error objectrejRes is RateLimiterRes objectrejRes is RateLimiterRes objectArguments:
key is usually IP address or some unique client idpoints number of points consumed. default: 1Fine key by points number of points for one duration.
Note: Depending on time penalty may go to next durations
Returns Promise, which:
RateLimiterResinsuranceLimiter isn't setup:
rejected when some Redis error happened, where reject reason rejRes is Error objecttimeoutMs exceeded, where reject reason rejRes is Error objectReward key by points number of points for one duration.
Note: Depending on time reward may go to next durations
Returns Promise, which:
RateLimiterResinsuranceLimiter isn't setup:
rejected when some Redis error happened, where reject reason rejRes is Error objecttimeoutMs exceeded, where reject reason rejRes is Error objectMake sure you've launched npm run eslint, before creating PR.
You can try to run npm run eslint-fix to fix some issues.
Appreciated, feel free!
FAQs
Node.js rate limiter by key and protection from DDoS and Brute-Force attacks in process Memory, Redis, MongoDb, Memcached, MySQL, PostgreSQL, Cluster or PM
The npm package rate-limiter-flexible receives a total of 411,769 weekly downloads. As such, rate-limiter-flexible popularity was classified as popular.
We found that rate-limiter-flexible demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 0 open source maintainers collaborating on the project.
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