On Sun, Jun 5, 2011 at 13:42, Joshua Marantz <jmara...@google.com> wrote: > This is a case where the content varies based on user-agent. The > recommendation on the mod_deflate doc page is add vary:user-agent for any > non-image. Can you think of a case where the absence of a vary:user-agent > header causes broken behavior when the content doesn't vary? > > I'm not objecting to setting vary:user-agent when content varies: that's > what it's for. I'm objecting to setting vary:user-agent when content does > *not* vary. The mod_deflate documentation unambiguously recommends setting > vary:user-agent, and my feeling is that this is to work around a bug that > exists only in IE5 or pre-2007 patch of IE6.
Sorry, Joshua, we're conflating things. You raised two issues in your original post: 1. Updating the mod_deflate documentation. Seems reasonable. The Vary: UA recommendation was added in 2002 during a general clean-up of the mod_deflate documentation and the commit log doesn't tell why. You could open a bugzilla issue or raise it on the httpd-dev mailing list (the former is the proper channel but the bugzilla is something of a graveyard). 2. mod_pagespeed second-guessing the user's intent. That still seems like an unambiguously bad idea. To touch on Magento again, its documentation links (or linked) directly to that section of the mod_deflate docs and people are using that. If your module scans for and neutralizes that Header directive, you will break someone's site.
