Yodlr Metrics Library

The goal of this library is to provide a consistent API for sending metrics from our NodeJS services.

This library exposes a constructor which provides the following metric API calls:

• count
• increment
• decrement
• timing
• timer
• gauge
• set

Using this library

Construction

Staticaly define host/port and prefixes

var opts = {
  prefix: 'services.myapp', //optional
  statsd: {
    prefix: 'account-uuid', // optional
    host: '10.1.1.5',
    port: 8125
  }
  on_error: function errorHandler(err) { // if not defined, will emit 'error' instead
    console.log(err);
  }
}

Pull host/port and prefix from etcd.

If the values change, yodlr-metrics will dynamically reconfigure how it sends data. You don't need to modify you code at all.

If insufficient data is provided in etcd, yodlr-metrics will emit an error which you should capture and probably log.

var opts = {
  etcdHost: '172.17.42.1', // default, optional
  etcdPort: 4001, // default, optional
  prefix: 'services.myapp', // optional
  statsd: {
    prefix_etcd: '/services/statsd/prefix', // optional
    hostEtcd: '/services/statsd/host',
    portEtcd: '/services/statsd/port'
  }
}

Once you've decided on your configuration, you can construct a metrics object like this:

var YodlrMetrics = require('yodlr-metrics');

var opts = {
  prefix: 'services.myapp',
  statsd: {
    prefix: 'account-uuid',
    host: '10.1.1.5',
    port: 8125
  }
}

var metric = new YodlrMetrics(opts);
metric.on('error', function metricError(err) {
  console.log('Uh oh, error in yodlr-metrics', err);
})

Count

Increases or decreased a counter by the provider number.

metric.count('users.new', 5); // increments counter by 5

Increment

Increases a counter by 1

metric.increment('users.new'); // increments counter by 1

Decrement

Decreases a counter by 1

metric.decrement('users.new'); // increments counter by 1

Timing

Sends a timing metric in ms

metric.timing('user.ping_latency', 50); // sends timing metric of 50ms

Timer

Variation on the timing metric which provides a timing object with a Stop() function

var timer = metric.createTimer('user.ping_latency');
setTimeout(function() {
  timer.stop(); // sends timing metric from when object was created
}, 50);

Gauge

Sets a currently configured gauge to this new value

metric.gauge('users.current_connected', 500); // sets gauge to 500

Set

Used to count unique occurrences of events between flushes, using a Set to store all occurring events.

If a method is called multiple times with the same value in the same sample period, that value will only be counted once.

metric.set('users.active', 'Jared');
metric.set('users.active', 'Tom');
metric.set('users.active', 'Jared'); //