app.js

const pm2 = require('pm2');
const pmx = require('pmx'); // docs say pmx is deprecated, module:generate still uses it, I confuze
const gelflog = require('gelf-pro');

const conf = pmx.initModule({
  widget: {
    logo: 'https://app.keymetrics.io/img/logo/keymetrics-300.png',
    theme: ['#141A1F', '#222222', '#3ff', '#3ff'],
  },
});

gelflog.setConfig({
  adapterName: conf.gelfAdapterName,
  adapterOptions: {
    host: conf.graylogHost,
    port: conf.graylogPort,
  }
});

if (conf.graylogFields) {
  try {
    const fields = JSON.parse(conf.graylogFields);

    gelflog.setConfig({ fields });
  } catch (ex) {
    console.log(`Could not parse JSON ${ex}`); // eslint-disable-line no-console
  }
}

function getLogData(data) {
  data=data.trim().replace(/\n/g, "\\\\n").replace(/\r/g, "\\\\r").replace(/\t/g, "\\\\t");
  try {
    json = JSON.parse(data);
    if (json.message.trim().length === 0) {
      return "";
    }
    return json;
  } catch(err) {
    return data;
  }
}

pm2.Client.launchBus((err, bus) => {
  if (err) return;

  bus.on('log:out', (log) => {
    if (log.process.name === 'pm2-gelf-pro') return;
    data = getLogData(log.data);
    if (typeof data === 'string'){
      if (data.length == 0) return;
      gelflog.info(data, {application_name: log.process.name});
    } else {
      data['application_name'] = log.process.name;
      gelflog.info(data.message, data);
    }
  });

  bus.on('log:err', (log) => {
    if (log.process.name === 'pm2-gelf-pro') return;
    data = getLogData(log.data);
    if (typeof data === 'string'){
      if (data.length == 0) return;
      gelflog.info(data, {application_name: log.process.name});
    } else {
      data['application_name'] = log.process.name;
      gelflog.info(data.message, data);
    }

  });

  bus.on('close', () => {
    pm2.disconnectBus();
  });
});

module.exports = {
  gelflog,
};