phantomas/modules/headers/headers.js

Headless Chromium-based web performance metrics collector and monitoring tool

/**
 * Analyzes HTTP headers in both requests and responses
 */
"use strict";

module.exports = function (phantomas) {
  phantomas.setMetric("headersCount"); // @desc number of requests and responses headers
  phantomas.setMetric("headersSentCount"); // @desc number of headers sent in requests
  phantomas.setMetric("headersRecvCount"); // @desc number of headers received in responses

  phantomas.setMetric("headersSize"); // @desc size of all headers
  phantomas.setMetric("headersSentSize"); // @desc size of sent headers
  phantomas.setMetric("headersRecvSize"); // @desc size of received headers

  phantomas.setMetric("headersBiggerThanContent"); // @desc number of responses with headers part bigger than the response body

  function processHeaders(headers) {
    var res = {
      count: 0,
      size: 0,
    };

    if (headers) {
      Object.keys(headers).forEach(function (key) {
        res.count++;
        res.size += (key + ": " + headers[key] + "\r\n").length;
      });
    }

    return res;
  }

  phantomas.on("request", function (entry) {
    var headers = processHeaders(entry.headers);

    phantomas.incrMetric("headersCount", headers.count);
    phantomas.incrMetric("headersSize", headers.size);

    phantomas.incrMetric("headersSentCount", headers.count);
    phantomas.incrMetric("headersSentSize", headers.size);
  });

  phantomas.on("recv", function (entry) {
    var headers = processHeaders(entry.headers);

    phantomas.log(
      "%s: %d / %d",
      entry.url,
      entry.headersSize,
      entry.transferedSize
    );

    // phantomas.log('Headers: <%s> %d bytes', entry.url, headers.size);

    phantomas.incrMetric("headersCount", headers.count);
    phantomas.incrMetric("headersSize", entry.headersSize);

    phantomas.incrMetric("headersRecvCount", headers.count);
    phantomas.incrMetric("headersRecvSize", entry.headersSize);

    // skip HTTP 204 No Content responses
    if (entry.status !== 204 && headers.size > entry.transferedSize) {
      phantomas.incrMetric("headersBiggerThanContent");
      phantomas.addOffender("headersBiggerThanContent", {
        url: entry.url,
        contentSize: entry.transferedSize,
        headersSize: entry.headersSize,
      });
    }
  });
};