@metrics/daemon

Daemon for collecting metrics over a network. Provides a stream for further piping of metrics.

Installation

$ npm install @metrics/daemon

Example

Set up a daemon with UDP on port 6000 as transport and pipes the incomming metrics into the @metrics/client:

const Daemon = require('@metrics/daemon');
const Client = require('@metrics/client');

const daemon = new Daemon('udp', { port: 6000 });
const client = new Client();

daemon.pipe(client);

daemon.listen();

Description

This module makes it possible to create a socket one can recieve metrics over. The socket can be of different protocols (UDP, TCP etc) but the data trasmitted over it is expected to be of the @metrics/metric type. The recieved metrics can be piped to other metric modules for further handling.

For sending metrics over a socket one are expected to use the @metrics/emitter module.

The main purpose of this is to be able to collect metrics from multiple processes. Here is a simplified example of each worker in a cluster pushing metrics to the master and the master pushing the metric further:

const master = () => {
    const daemon = new Daemon('udp', { port: 6000 });
    const client = new Client();

    daemon.pipe(client);

    daemon.listen();
};

const worker = () => {
    const emitter = new Emitter('udp', { port: 6000 });
    const client = new Client();

    client.pipe(emitter);

    client.metric({
        name: `worker_${cluster.worker.id}`,
        description: `Worker number: ${cluster.worker.id}`,
        value: 1,
    });
};

const workers = [];

if (cluster.isMaster) {
    for (let i = 0; i < (os.cpus().length - 1); i++) {
        workers.push(cluster.fork());
    }
    master();
}

if (cluster.isWorker) {
    worker();
}

See the cluster example in examples for a full example.

Constructor

Create a new Daemon instance.

const Daemon = require('@metrics/daemon');
const daemon = new Daemon(transport, options);

transport (required)

What type of transport to use. Supported values are:

• udp - For UDP transport.

options (optional)

An Object containing misc configuration for the selected transport. Please see each transport for which option which can be passed in.

returns

Returns a Readable stream in object mode.

API

The Daemon instance has the following API:

.listen()

Starts the daemon with the selected transport.

Transports

The following transports is supported:

UDP

UDP as a transport can be enabled by providing udp to the transport argument on the Daemon constructor. The UDP transport takes the following options (passed to the options argument on the Daemon constructor):

• port - Number - The port to bind to. Default: 40400.
• address - String - The address to bind to. Default: localhost.
• logger - Function - Any logger that implements the methods trace, debug, info, warn, error and fatal. Under the hood abslog is used. See that module for further information. If no logger is passed in, nothing will be logged.