X-Magento-Cache-Control Header Extra Variables

Question

Has anyone else had the issue with 2.2.6 and Varnish 5, where extra variables are included in the header?

My header retruns;

X-Magento-Cache-Control: max-age=86400, public, s-maxage=86400, max-age=0, no-cache, s-maxage=10

Where i would expect it to return;

X-Magento-Cache-Control: max-age=86400, public, s-maxage=86400

Does anyone know how this is possible please?

Answer 1

Apache module Mod_pagespeed was adding the extra headers in apache which were then appended to the magento headers.

Turns out that it only happens if varnish is enabled in the backend. If you run varnish and set the back end to built in cache then the pagespeed headers are not appended to the magento headers.