Metrics

Metrics is a reporting framework for data point information (measurements and time series) to aggregators such as Graphite

Highlights

• Time series reporting
• Support pluggable reporters
• Built in reporters:
  • Graphite
  • String
  • Console
  • InMemory (for testing)
• Simple, easy to use API

Getting started

Installation

Configuration

Import metrics package:

const Metrics = require('@shopyourway/metrics').Metrics;

Initialize the metrics instance with the required reporters:

const stringReporter = new require('@shopyourway/metrics').StringReporter(metricString => {
	// Do something
});
const consoleReporter = new require('@shopyourway/metrics').ConsoleReporter();

const metrics = new Metrics([stringReporter, consoleReporter], errorHandler);

Reporting execution time

Use the Metrics instance to report execution time of a function:

metrics.space('users.get').meter(function(userIds, callback) {
	// read users from database
	callback(...);
});

• You may use the space function to define the namespace key that will be used to aggregate the time
• when you wish to meter a function, use the meter function and pass a function with you code into it. the meter function will run your code, while measuring the time it took to execute, and report it to the configured reporters

Note that the metrics is reported only after the callback is called.

Reporters

Metrics comes with several built-in reporters

Graphite

Reports metrics to a graphite server:

const metrics = require('@shopyourway/metrics').Metrics;

const graphiteHost = '1.1.1.1'; // Graphite server IP address
const graphitePort = 2003; // Optional - port number. Defaults to 2003
const spacePrefix = 'My.Project'; // Optional - prefix to all metrics spaces

const graphiteReporter = new require('@shopyourway/metrics').GraphiteReporter({
		host: graphiteHost,
		port: graphitePort,
		prefix: spacePrefix
	});

const metrics = new Metrics([graphiteReporter], errorHandler);

Console

Console reporter comes in handy when you need to debug metrics calls:

const Metrics = require('@shopyourway/metrics').Metrics;

const consoleReporter = new require('@shopyourway/metrics').ConsoleReporter();
	
const metrics = new Metrics([consoleReporter], errorHandler);

When a metrics will be reported, a message will appear in the terminal, that includes the key and the value reported.

String

const Metrics = require('@shopyourway/metrics').Metrics;
const fs = require('fs');

const stringReporter = new require('@shopyourway/metrics').StringReporter(metricString => {
	fs.appendFile('metrics.log', metricsString);
});
	
const metrics = new Metrics([stringReporter], errorHandler);

Here, StringReporter is used to build a log file from the metrics reports.

InMemory

InMemoryReporter can be used for testing purposed, in order to make sure your code reports metrics as expected.

const Metrics = require('@shopyourway/metrics').Metrics;

const metricsStorage = [];

const memoryReporter = new require('@shopyourway/metrics').InMemoryReporter(metricsStorage);
	
const metrics = new Metrics([memoryReporter], errorHandler);

When a metric is reported, an object with key and value properties is pushed to the array. Then, the array can be used in order to validate the report.

Building new reporters

Metrics support creating new reports acccording to an application needs.

A reporter must contain a method called report. The method gets the reported key and value.

For example, lets see how to implement a reporter for redis:

const client = require('redis').createClient();

module.exports = function RedisReporter(channel) {
  this.report = function(key, value) {
    client.publish(channel, JSON.stringify({ key: key, value: value }));
  }
};

The new reporter will pusblish a message to a specified channel in redis when a metric is reported.

Development

How to contribute

We encorage contribution via pull requests on any feature you see fit.

When submitting a pull request make sure to do the following:

• Check that new and updated code follows OhioBox existing code formatting and naming standard
• Run all unit and integration tests to ensure no existing functionality has been affected
• Write unit or integration tests to test your changes. All features and fixed bugs must have tests to verify they work Read GitHub Help for more details about creating pull requests

Running tests

To run tests, in command line simply run npm test