Install procedures to enable W3TC as a WordPress MU (must-use) plugin.

w3tc-mu.md

###W3TC MU-Plugins Install

1. ####Add Apache Rewrite Rule -> .htaccess:

   • RewriteRule ^wp-content/plugins/w3-total-cache(/.*|)$ /wp-content/mu-plugins/w3-total-cache$1 [L,NC]

2. ####Add WP-Config Option -> wp-config.php:

   • define('W3TC_DIR', dirname(FILE).'/wp-content/mu-plugins/w3-total-cache');

3. ####Add w3tc plugin -> mu-plugins/:

   • Upload entire plugin to mu-plugins/w3-total-cache/

4. ####Add mu-plugin wrapper file -> mu-plugins/w3-total-cache.php

   • <?php require WPMU_PLUGIN_DIR.'/w3-total-cache/w3-total-cache.php';

Some notes on the above.

• The apache rewrite makes the wp-admin side pretty and redirects all assets for js/css to the mu-plugins url.
• The wp-config.php constant simply ensures all php scripts for W3TC point to the mu-plugins path.
• The latter two edits simply make the plugin must-use in WP so that it is always on, and cannot be updated automatically.

The most important config to setup is to enable all caching modes—page caching, browser cache and db caching.

@wturnerharris These notes were fantastically helpful and saved me a lot of time, thanks!

Are you still using w3tc in the mu-plugins context? The problem I'm running into now is that the activation hook doesn't run when the plugin is in mu-plugins, so for new sites, the wp_x_w3tc_cdn_queue table doesn't get created. I'm working on a solution, but just thought I'd check if you'd also run into this.

Also for whoever it helps, I have forked this gist and updated the rewrite rule for nginx as opposed to apache.

I also had to set another constant:

define( 'W3TC_EXTENSION_DIR', WP_CONTENT_DIR' . '/mu-plugins' );