Modules that break caching, and how to fix them
Admin (v. 2.0)
Problem
Adds a DrupalAdminToolbar cookie that is needed server-side to prevent "slow load JS flicker"
Solution
Most users won't have access to the admin toolbar, so this is probably a moot point
More Info
See this exchange with module's maintainer, yhahn, on #open-atrium:
EvanDonovan: it is checked server side for rather trivial stuff | |
<EvanDonovan> | yhahn: if it were not present would that be bad. |
<yhahn> | well not trivial but I believe you could exclude it if it is an issue |
<yhahn> | it basically sets the initial css classes for the toolbar/body |
<EvanDonovan> | b/c if i strip it in Varnish VCL then it won't be there |
<EvanDonovan> | ah ok |
<EvanDonovan> | i was hoping that would only happen client-side |
<yhahn> | it's there to prevent slow-load js flicker |
<EvanDonovan> | i will not strip it if the server-side checks are done in the theming layer |
<EvanDonovan> | yeah, that makes sense |
<EvanDonovan> | i will keep it then |
<EvanDonovan> | most of the time it will be moot point |
<yhahn> | cools |
<EvanDonovan> | b/c most users with access to admin toolbar will not be anonymous |
Autologout
Problem
Adds a "autologout_hits" cookie to anonymous pages.
Solutions
Disable the module
(Question: is this cookie necessary server-side? If not, then it could be stripped out in vcl_recv, without disabling the module.)
CiviCRM
Problem
Adds an empty $_SESSION["CiviCRM"] to many types of pages, which creates a session cookie unnecessarily. Two hooks that this happens for are: hook_user() and hook_block().
Solution
In civicrm/drupal/civicrm.module:
Change the bottom of the civicrm_initialize() function to the following:
// fix needed for Pressflow lazy session initialization -
// if $_SESSION['CiviCRM'] is empty, unset it
if(empty($_SESSION['CiviCRM'])) {
unset($_SESSION['CiviCRM']); }
return true;
This will ensure that the CiviCRM session variable is only set as needed, and keep other pages cacheable by an external system.
As yet untested solution (from dlobo in #civicrm):
In civicrm/CRM/Core/Session.php:
Remove the $this->create(); line from the session's constructor function. Following patch is pasted from IRC and may need modification to apply. If so, please update this listing. Also, update if this works, so it can become the recommended solution.
svn diff CRM/Core/Session.php
Index: CRM/Core/Session.php
===================================================================
--- CRM/Core/Session.php (revision 26441)
+++ CRM/Core/Session.php (working copy)
@@ -84,8 +84,6 @@
function __construct()
{
$this->_session =& $_SESSION;
- $this->create();
}
Collapsiblock
Problem
Sets a cookie that is only needed on client-side.
Solution
Varnish
Modify the line that strips out cookies in vcl_recv:
// Remove has_js and Google Analytics __* cookies. Also remove collapsiblock cookies. set req.http.Cookie = regsuball(req.http.Cookie, "(^|;\s*)(__[a-z]+|__utma_a2a|has_js|collapsiblock)=[^;]*", "");
Global Redirect
Problem
When Global Redirect is enabled, http://www.example.com/node?page=X will always receive a 301 Moved Permanently.
Solutions
Varnish
Add the following to vcl_recv
if (req.url ~ "node\?page=[0-9]+$") {
set req.url = regsub(req.url, "node(\?page=[0-9]+$)", "\1");
return (lookup);
}
Masquerade
Problem
Masquerade will start a $_SESSION value on every pageload in hook_init, thus creating a session cookie and breaking caching.
Solutions
Patch/Fix for Module
This patch was applied to version 6.x-1.7.
mobile_tools
Problem
Mobile_tools will add to the = $_SESSION value on every pageload, thus creating a session cookie and breaking caching.
Solutions
Do it in Varnish
I have not done this yet, but here are examples:
http://www.varnish-cache.org/trac/wiki/VCLExampleRedirectInVCL
http://www.varnish-cache.org/trac/wiki/VCLExampleHostnameRemapping
The mobile_tools PHP code has a much more complete regex of mobile user agents, that should probably be copied into any vcl solution.