spee.ch/server/middleware/logMetricsMiddleware.js

const logger = require('winston');
const db = require('../models');
const httpContext = require('express-http-context');

function logMetricsMiddleware (req, res, next) {
  res.on('finish', () => {
    const userAgent = req.get('user-agent');
    const routePath = httpContext.get('routePath');

    let referrer = req.get('referrer');

    if (referrer && referrer.length > 255) {
      try {
        // Attempt to "safely" clamp long URLs
        referrer = /(.*?)#.*/.exec(referrer)[1];
      } catch (e) {
        // Cheap forced string conversion & clamp
        referrer = String(referrer);
        referrer = referrer.substr(0, 255);
      }

      if (referrer.length > 255) {
        logger.warn('Request refferer exceeds 255 characters:', referrer);
        referrer = referrer.substring(0, 255);
      }
    }

    db.Metrics.create({
      time      : Date.now(),
      isInternal: /node-fetch/.test(userAgent),
      isChannel : res.isChannel,
      claimId   : res.claimId,
      routePath : httpContext.get('routePath'),
      params    : JSON.stringify(req.params),
      ip        : req.headers['x-forwarded-for'] || req.connection.remoteAddress,
      request   : req.url,
      routeData : JSON.stringify(httpContext.get('routeData')),
      referrer,
      userAgent,
    });
  });

  next();
}

function setRouteDataInContextMiddleware (routePath, routeData) {
  return function (req, res, next) {
    httpContext.set('routePath', routePath);
    httpContext.set('routeData', routeData);
    next();
  };
}

module.exports = {
  logMetricsMiddleware,
  setRouteDataInContextMiddleware,
};