express-metering

simple express middleware to meter api requests.

Installation

This repository is available in npm repository. It needs node v4 or higher.

$ npm install express-metering

Usecase

This package is intended for a API service which servers single or multiple clients using express framework. It will meter(or measure)the requests made from a remote address per client_id per hour. express-metering will have a request throttling component very soon.

• Requests throttling per client per hour for overall health of the service. (future planned release)
• To identify malicious request origins which bombarding your service with requests.
• To identify and isolate key restful resources which are accessed more than others.

Usage

Each API request is stored in bucket uniquely identified by.

• ip- remote address
• clientId - An application probably serve multiple clients
• utcHour

To use this package, simply pass the middleware in the express middleware chain before the routes.

var app = express();
var metering = require('express-metering');

// default configuration 
app.use( metering.meter() );

The middleware attaches the count/hour/client to the req object to be accessed down the middleware chain. To access the value downstream:

console.log(req.meter.count); // contains an Integer count of number of requests for the client in the last utcHour.

To use other stores instead of default memoryStore, scroll down to see Stores section.

Options

name	Default	description
proxy	false	express server behind proxy, true remote address will be found in header ( default header : x-forwarded-for)
proxyForwardedHeader	x-forwarded-for	header name set by proxy server containing true client remote address
store	memoryStore	Store used to store api request counts. Default store keeps data in memory.
clientIdPath	"client.id"	The nested path in req object where client ID where the request originated. Each API request is stored against a clientID.

Stores

Stores persist the request counts against each remote address(ip)/ hour. Currently this package supports :

• memoryStore

  var app = express();
  var expressMetering = require('express-metering');
  app.use( expressMetering.meter() );

• mongoStore MongoStore persists data and protects metering info against server crashes. It unfortunately adds 1 DB access call which in turn adds ~100ms to your API call latency.

  var app = express();
  var expressMetering = require('express-metering');
  var store = new expressMetering.mongoStore({
    uri : "mongodb://username:password@mongo_server_ip/db_name"
  });
  app.use( expressMetering.meter({ store: store }) );

• redisStore

  var app = express();
  var expressMetering = require('express-metering');
  var store = new expressMetering.redisStore({
    host : "redis_url",
    port : redis_port || 6379
  });
  app.use( expressMetering.meter({ store: store }) );

Support for the following stores is planned for near future releasese:

• Memcached
• Mysql