express-status-monitor/src/helpers/socket-io-init.js

Realtime Monitoring for Express-based Node applications

/* eslint strict: "off", init-declarations: "off" */

'use strict';

const socketIo = require('socket.io');
const gatherOsMetrics = require('./gather-os-metrics');

let io;

const addSocketEvents = (socket, config) => {
  socket.emit('esm_start', config.spans);
  socket.on('esm_change', () => {
    socket.emit('esm_start', config.spans);
  });
};

module.exports = (server, config) => {
  if (io === null || io === undefined) {
    if (config.websocket !== null) {
      io = config.websocket;
    } else {
      io = socketIo(server);
    }

    io.on('connection', socket => {
      if (config.authorize) {
        config
          .authorize(socket)
          .then(authorized => {
            if (!authorized) socket.disconnect('unauthorized');
            else addSocketEvents(socket, config);
          })
          .catch(() => socket.disconnect('unauthorized'));
      } else {
        addSocketEvents(socket, config);
      }
    });

    config.spans.forEach(span => {
      span.os = [];
      span.responses = [];
      const interval = setInterval(() => gatherOsMetrics(io, span), span.interval * 1000);

      // Don't keep Node.js process up
      interval.unref();
    });
  }
};