Socket.io-prometheus-metrics NPM

socket.io-prometheus-metrics

Exposes a metrics endpoint for prometheus to collect data about socket.io.

Installation

npm install socket.io-prometheus-metrics

Usage

Basic usage

import * as http from 'http';
import * as io from 'socket.io';
import * as prometheus from 'socket.io-prometheus-metrics';

const server = http.createServer();
const io = io(server);

prometheus.metrics(io);

server.listen(3000);

Metrics is then available at localhost:9090/metrics.

Prometheus default metrics can also be enabled by setting the collectDefaultMetrics option to true

prometheus.metrics(io, {
    collectDefaultMetrics: true
});

If you wish to serve the metrics yourself the createServer options can be set to false and metrics can be collected from the register

const ioMetrics = prometheus.metrics(io, {
    createServer: false
});

const metrics = ioMetrics.register.metrics();

Options

Option	Default	Description
`path`	"/metrics"	Metrics path
`port`	9090	Metrics port
`createServer`	true	Auto create http server
`collectDefaultMetrics`	false	Collect prometheus default metrics
`checkForNewNamespaces`	true	Collect metrics for namespaces that will be added at runtime

Socket.io metrics

all metrics have socket_io_ prefix in their names.

Name	Help	Labels
`socket_io_connected`	Number of currently connected sockets
`socket_io_connect_total`	Total count of socket.io connection requests	`namespace`
`socket_io_disconnect_total`	Total count of socket.io disconnections	`namespace`
`socket_io_errors_total`	Total count of socket.io errors	`namespace`
`socket_io_events_received_total`	Total count of socket.io recieved events	`event`, `namespace`
`socket_io_events_sent_total`	Total count of socket.io sent events	`event`, `namespace`
`socket_io_recieve_bytes`	Total socket.io bytes recieved	`event`, `namespace`
`socket_io_transmit_bytes`	Total socket.io bytes transmitted	`event`, `namespace`

Prometheus default metrics

available if collectDefaultMetrics is set to true

More information here and here.

Namespaces support

Default namespace has label value of '/'.

By default library checks io.nsps variable for new namespaces to collect metrics from. This check occurs every 2 seconds.

You can disable this functionality by providing checkForNewNamespaces option with false value. For example:

prometheus.metrics(io, {
    checkForNewNamespaces: false
});

With this functionality disabled, library will only collect metrics from namespaces that were available at the moment of call to prometheus.metrics(io, ...), default namespace is included.

More information about socket.io namespaces here.