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librato-node is a Node.js client for Librato Metrics (

build status npm version mit license we're hiring

Getting Started


$ npm install librato-node


Once librato.start is called, a worker will send aggregated stats to Librato once every 60 seconds.

var librato = require('librato-node');

librato.configure({email: '', token: 'ABC123'});

process.once('SIGINT', function() {
  librato.stop(); // stop optionally takes a callback

// Don't forget to specify an error handler, otherwise errors will be thrown
librato.on('error', function(err) {


Use librato.increment to track counts in Librato. On each flush, the incremented total for that period will be sent.

var librato = require('librato-node');

librato.increment('foo');                     // increment by 1
librato.increment('foo', 2);                  // increment by 2
librato.increment('foo', 2, {source: 'bar'}); // custom source


You can send arbitrary measurements to Librato using librato.measure. These will be sent as gauges. For example:

var librato = require('librato-node');

librato.measure('member-count', 2001);
librato.measure('response-time', 500);
librato.measure('foo', 250, {source: 'bar'}); // custom source


Use librato.timing to measure durations in Librato. You can pass it a synchronous function or an asynchronous function (it checks the function arity). For example:

var librato = require('librato-node');

// synchronous
librato.timing('foo', function() {
  for (var i=0; i<50000; i++) console.log(i);

// async without a callback
librato.timing('foo', function(done) {
  setTimeout(done, 1000);

// async with a callback
var workFn = function(done) {
  setTimeout(function() {
    done(null, 'foo');
var cb = function(err, res) {
  console.log(res); // => 'foo'
librato.timing('foo', workFn, cb);
librato.timing('foo', workFn, {source: 'bar'}, cb); // all timing calls also accept a custom source


librato-node includes Express middleware to log the request count and response times for your app. It also works in other Connect-based apps.

var express = require('express');
var librato = require('librato-node');

var app = express();

The key names the middleware uses are configurable by passing an options hash.

librato.middleware({requestCountKey: 'myRequestCount', responseTimeKey: 'myResponseTime'});


By default the librato-node worker publishes data every 60 seconds. Configure this value by passing a period argument to the configure hash.

var librato = require('librato-node');
librato.configure({email: '', token: 'ABC123', period: 5000})

Request Options

You can pass additional options for the HTTP POST to Librato using the requestOptions parameter. See request/request for a complete list of options. For example, to configure a timeout:

var librato = require('librato-node');
librato.configure({email: '', token: 'ABC123', requestOptions: {timeout: 250}})

By default librato-node will retry up to 3 times on connection failures and 5xx responses using an exponential backoff strategy with a 100ms base. These defaults can be overridden using the requestOptions paramter. See requestretry for a list of options. For example, to limit to a single attempt:

var librato = require('librato-node');
librato.configure({email: '', token: 'ABC123', requestOptions: {maxAttempts: 1}})


$ git clone && cd librato-node
$ npm install
$ npm test


librato-node is largely based off of Librato's own librato-rack. Visit that repository if you're running Ruby or for more information on Librato Metrics in general.