How to force a browser to refresh a cached version

Question

I have a website that because of an ill-prepared apache conf file has instructed users to cache a website URL several years into the future. As a result, when a person visits the site, they often make no attempt to even request the page. The browser just loads the HTML from cache.

This website is about to get a major update, and I would like for users to be able to see it. Is there a way for me to force a user to actually re-request the webpage? I fear that for some users, unless they happen to press F5, they may see the old webpage for several years.

Answer 1

You can make all the necessary changes inside the HTML files, like

<meta http-equiv="cache-control" content="no-cache, must-revalidate, post-check=0, pre-check=0" />
<meta http-equiv="cache-control" content="max-age=0" />
<meta http-equiv="expires" content="0" />
<meta http-equiv="expires" content="Tue, 01 Jan 1980 1:00:00 GMT" />
<meta http-equiv="pragma" content="no-cache" />

But also, you can explicitely tell Apache to use mod_expires.c module, and add a couple of directives to httpd.conf file:

<IfModule mod_expires.c>
  # Turn on the module.
  ExpiresActive on
  # Set the default expiry times.
  ExpiresByType text/html "modification plus 5 seconds"
  ExpiresByType text/javascript "modification plus 5 seconds"
  ExpiresDefault "access plus 2 days"
</IfModule>

This way you add the http headers cache-control and expires, to responses, in order for thw browser to update the cache 5 seconds after the file was modified in the origin, for those kinds of files, and 2 days after being accessed by the browser for all the other kinds of files.

Hope this helps.

Answer 2

It is arguable that if your "major update" is just in a few (2 or 3) weeks, you only need to reconfigure your apache conf now (no far future stuff for html - only for assets and content that will most likely never change). The Firefox cache is ~50MB by default and that is not much because images get also cached and modern websites have a lot of content.

Not perfect - but thats what I would do - when I don't want to or can't change the URL's ;)