node-service-metrics

The 'service-metrics' gather metric information about the running process.

BEWARE, because of usage this module does not work well on Windows: your node-gyp needs to properly installed (see here).

Features

• gather interval can be configured
• gathered metrics are customisable through an easy API
• Tasks can be set to be executed at the end of each interval

Take a look to the TODO if you want to help towards the next steps.

Usage

Node Dependencies

Add following line to your project dependencies

"service-metrics": "0.1.x",

then hit

npm install

Require module

var metrics = require('service-metrics');

configure

You can pass an options object as you require the library:

var metrics = require('service-metrics')(options);

Available Options

• disable_cpu_metrics (boolean): library will not return any information about cpu usage (default: false).
• disable_memory_metrics (boolean): library will not return any information about memory usage (default: false).
• interval (number): metrics report interval time in milliseconds (default: 5000)

API

set([persistent-]name [, simple_counter])

Sets a custom metric. Two types of custom metrics are avalaible: the "simple counter" an integer value which gets incremented by one and the "value collection" which gets incremented by custom values and returns an object with the total value, the count of provided values in the cycle, the max, average and min value.

Parameters

• [persistent-]name (string): the name of the metric. If prefix "persistent-" is used, the metric will not be reset at the end of the cycle
• simple_counter (boolean): the type of the metric (default is true)

Example

// simple counter
metrics.set('counter');

// simple counter that will not be reset
metrics.set('persistent-counter');

// value collection
metrics.set('collection', false);

// value collection that will not be reset
metrics.set('persistent-collection', false);

incr([persistent-]name [, value])

Increments a custom metric.

Parameters

• [persistent-]name (string): the name of the metric
• value (number): the numeric value to be added (only for collection type)

Example

// simple counter gets incremented by +1
metrics.incr('counter');

// value collection gets new element: 23
metrics.incr('collection', 23);

exists(name)

Checks if the specified metric exists and return a boolean.

Parameters

• name (string): the name of the metric

Example

// returns true
metrics.exists('counter');

// returns false
metrics.exists('doesNotExist');

addTask(name, task)

Defines a task to be executed at the end of each cycle. The task gets the actual metric object as argument.

Parameters

• name (string): the name of the task
• task (function): a custom function taking metrics as argument

Example

// show the metrics
metrics.addTask('log', console.log);

// custom task
metrics.addTask('custom', function (metrics) {
  console.log('Show actual metrics:');
  console.log(metrics);

  /* do something */
});

setInterval(milliseconds)

Defines the cycle interval within the range of one second to two minutes.

Parameter

• milliseconds (number): value in the range 1000 to 120000

Example

// set the cycle interval to 3 seconds
metrics.setInterval(3000);