@hyperlab-solutions/express-rate-limit
v2.9.0
Published
Basic IP rate-limiting middleware for Express. Use to limit repeated requests to public APIs and/or endpoints such as password reset.
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Express Rate Limit
Basic rate-limiting middleware for Express. Use to limit repeated requests to public APIs and/or endpoints such as password reset.
Note: this module does not share state with other processes/servers by default. If you need a more robust solution, I recommend adding the Redis Store or checking out strict-rate-limiter, express-brute, or rate-limiter - all are excellent pieces of software.
Install
$ npm install --save @hyperlab-solutions/express-rate-limit
Usage
For an API-only server where the rate-limiter should be applied to all requests:
var RateLimit = require('@hyperlab-solutions/express-rate-limit');
app.enable('trust proxy'); // only if you're behind a reverse proxy (Heroku, Bluemix, AWS if you use an ELB, custom Nginx setup, etc)
var limiter = new RateLimit({
windowMs: 15*60*1000, // 15 minutes
max: 100, // limit each IP to 100 requests per windowMs
delayMs: 0 // disable delaying - full speed until the max limit is reached
});
// apply to all requests
app.use(limiter);
For a "regular" web server (e.g. anything that uses express.static()
), where the rate-limiter should only apply to certain requests:
var RateLimit = require('@hyperlab-solutions/express-rate-limit');
app.enable('trust proxy'); // only if you're behind a reverse proxy (Heroku, Bluemix, AWS if you use an ELB, custom Nginx setup, etc)
var apiLimiter = new RateLimit({
windowMs: 15*60*1000, // 15 minutes
max: 100,
delayMs: 0 // disabled
});
// only apply to requests that begin with /api/
app.use('/api/', apiLimiter);
Create multiple instances to apply different rules to different routes:
var RateLimit = require('@hyperlab-solutions/express-rate-limit');
app.enable('trust proxy'); // only if you're behind a reverse proxy (Heroku, Bluemix, AWS if you use an ELB, custom Nginx setup, etc)
var apiLimiter = new RateLimit({
windowMs: 15*60*1000, // 15 minutes
max: 100,
delayMs: 0 // disabled
});
app.use('/api/', apiLimiter);
var createAccountLimiter = new RateLimit({
windowMs: 60*60*1000, // 1 hour window
delayAfter: 1, // begin slowing down responses after the first request
delayMs: 3*1000, // slow down subsequent responses by 3 seconds per request
max: 5, // start blocking after 5 requests
message: "Too many accounts created from this IP, please try again after an hour"
});
app.post('/create-account', createAccountLimiter, function(req, res) {
//...
});
A req.rateLimit
property is added to all requests with the limit
, current
, and remaining
number of requests for usage in your application code.
Configuration
- windowMs: milliseconds - how long to keep records of requests in memory. Defaults to
60000
(1 minute). - delayAfter: max number of connections during
windowMs
before starting to delay responses. Defaults to1
. Set to0
to disable delaying. - delayMs: milliseconds - how long to delay the response, multiplied by (number of recent hits -
delayAfter
). Defaults to1000
(1 second). Set to0
to disable delaying. - max: max number of connections during
windowMs
milliseconds before sending a 429 response. Defaults to5
. Set to0
to disable. - message: Error message returned when
max
is exceeded. Defaults to'Too many requests, please try again later.'
- statusCode: HTTP status code returned when
max
is exceeded. Defaults to429
. - headers: Enable headers for request limit (
X-RateLimit-Limit
) and current usage (X-RateLimit-Remaining
) on all responses and time to wait before retrying (Retry-After
) whenmax
is exceeded. - keyGenerator: Function used to generate keys. By default user IP address (req.ip) is used. Defaults:
function (req /*, res*/) {
return req.ip;
}
- skip: Function used to skip requests. Returning true from the function will skip limiting for that request. Defaults:
function (/*req, res*/) {
return false;
}
- handler: The function to execute once the max limit is exceeded. It receives the request and the response objects. The "next" param is available if you need to pass to the next middleware. Defaults:
function (req, res, /*next*/) {
if (options.headers) {
res.setHeader('Retry-After', Math.ceil(options.windowMs / 1000));
}
res.format({
html: function(){
res.status(options.statusCode).end(options.message);
},
json: function(){
res.status(options.statusCode).json({ message: options.message });
}
});
}
- onLimitReached: Function to listen each time the limit is reached. You can use it to debug/log. Defaults:
function (req, res, options) {
/* empty */
}
- store: The storage to use when persisting rate limit attempts. By default, the MemoryStore is used. It must implement the following in order to function:
function SomeStore() {
/**
* Increments the value in the underlying store for the given key.
* @method function
* @param {string} key - The key to use as the unique identifier passed
* down from RateLimit.
* @param {Store~incrCallback} cb - The callback issued when the underlying
* store is finished.
*/
this.incr = function(key, cb) {
// ...
};
/**
* This callback is called by the underlying store when an answer to the
* increment is available.
* @callback Store~incrCallback
* @param {?object} err - The error from the underlying store, or null if no
* error occurred.
* @param {number} value - The current value of the counter
*/
/**
* Resets a value with the given key.
* @method function
* @param {[type]} key - The key to reset
*/
this.resetKey = function(key) {
// ...
};
};
Avaliable data stores are:
- MemoryStore: (default)Simple in-memory option. Does not share state when app has multiple processes or servers.
- rate-limit-redis: Redis-backed store, more suitable for large or demanding deployments.
The delayAfter
and delayMs
options were written for human-facing pages such as login and password reset forms.
For public APIs, setting these to 0
(disabled) and relying on only windowMs
and max
for rate-limiting usually makes the most sense.
Instance API
- resetKey(key): Resets the rate limiting for a given key. (Allow users to complete a captcha or whatever to reset their rate limit, then call this method.)
v2 changes
v2 uses a less precise but less resource intensive method of tracking hits from a given IP. v2 also adds the limiter.resetKey()
API and removes the global: true
option.
License
MIT © Nathan Friedly