Prometheus metrics for socket.io
npm install socket.io-prom-metricssocket.io.
bash
npm install socket.io-prom-metrics
`
Usage
Basic usage
`ts
// server.ts
import { createServer } from "http";
import { Server, Socket } from "socket.io";
import * as prometheus from "socket.io-prom-metrics";
const server = createServer();
const io = new Server(server);
io.on("connection", (socket: Socket) => {
console.log(${socket.id} is connected.)
// Add event here
});
io.of("/custom-namespace").on("connection", (socket: Socket) => {
console.log(${socket.id} is connected.)
// Add event here
});
// init prometheus
prometheus.metrics(io); // running on port 9090 (default port) | http://localhost:9090/metrics
// start server
server.listen(3000, () => {
console.log("prometheus running on port 9090 : http://localhost:9090/metrics");
console.log("server running on port 3000")
});
`
If you wish to serve the metrics yourself the createServer options can be set to false and metrics can be collected from the register
`ts
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 received events | event, namespace |
| socket_io_events_sent_total | Total count of socket.io sent events | event, namespace |
| socket_io_receive_bytes | Total socket.io bytes received | 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:
`ts
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, ...)`,