express-statsd

StatsD route monitoring middleware for Connect/Express. This middleware can be used either globally or on a per-route basis (preferred) and sends status codes and response times to StatsD.

Installation

npm install express-statsd

Usage

An example of an express server with express-statsd:

var express = require('express');
var expressStatsd = require('express-statsd');
var app = express();
 
app.use(expressStatsd());
 
app.get('/', function (req, res) {
  res.send('Hello World!');
});
 
app.listen(3000);

By default, the middleware will send status_code and response_time stats for all requests. For example, using the created server above and a request to http://localhost:3000/, the following stats will be sent:

status_code.200:1|c
response_time:100|ms

Per route example

However, it's highly recommended that you set req.statsdKey which will be used to namespace the stats. Be aware that stats will only be logged once a response has been sent; this means that req.statsdKey can be set even after the express-statsd middleware was added to the chain. Here's an example of a server set up with a more specific key:

var express = require('express');
var expressStatsd = require('express-statsd');
var app = express();
 
function statsd (path) {
  return function (req, res, next) {
    var method = req.method || 'unknown_method';
    req.statsdKey = ['http', method.toLowerCase(), path].join('.');
    next();
  };
}
 
app.use(expressStatsd());
 
app.get('/', statsd('home'), function (req, res) {
  res.send('Hello World!');
});
 
app.listen(3000);

A GET request to / on this server would produce the following stats:

http.get.home.status_code.200:1|c
http.get.home.response_time:100|ms

Plain http example

This module also works with any http server

var http = require('http');
var expressStatsd = require('express-statsd');
 
var monitorRequest = expressStatsd();
 
http.createServer(function (req, res) {
    monitorRequest(req, res);
 
    // do whatever you want, framework, library, router
    res.end('hello world');
}).listen(3000);

Options

expressStatsd(options);

• options Object - Container for settings
  • client Object - The statsd client. Defaults to lynx with host set to 127.0.0.1 and port set to 8125.
  • requestKey String - The key on the req object at which to grab the key for the statsd logs. Defaults to req.statsdKey.