One Post-WordPress-3.1 Plugin Upgrade – and The Challenge of “mu-plugins”

After the upgrade of the site to WordPress 3.1, a couple of users noticed one little detail… they couldn’t use the new YouTube embed codes – the ones that use the <iframe> tag so that the video can be viewed on different devices like the iPad and iPhone that don’t, well, support Flash.

Now what was strange was that this had worked perfectly fine before. Two years ago I’d installed the Unfiltered MU plugin specifically to allow anyone with “Editor” access or above to be able to embed iframes or anything else they wanted.

Care to guess the problem?

Yep… I hadn’t updated the Unfiltered MU plugin since that first installation.

Oops.

A quick visit to the Unfiltered MU plugin site got me the latest version and very quickly our folks were back in action embedding iframes. Obviously something in WP 3.x broke whatever was in the old version of the Unfiltered Mu plugin I had installed.

The Problem With “mu-plugins”

And therein lies the problem with the mu-plugins directory inside of WordPress.

You have NO way of knowing when any plugins in that directory need updating.

To review, in a WordPress 3.x Multi-Site (formerly known as “WordPress MU”), there are TWO directories into which you can place plugins:

• wp-content/plugins – where all regular plugins go. These get activated for each blog or now can be activated network wide… but through the WP admin interface.
• wp-content/mu-plugins – where previously (in WPMU) all “network-wide” plugins went. There is no admin interface to activate these plugins… place a plugin in this directory and it is immediately activated.

The mu-plugins directory still works in WP 3.x Multi-Site and still does the same activation across all your blogs. Some plugins may still need to be placed there.

The challenge is, as I said, that you don’t see the update status of the plugins in mu-plugins in all the spiffy update/upgrade interfaces now in WordPress 3.x.

There are really two paths I can see:

1. Someone adds a function to WordPress to treat mu-plugins like the regular plugins directory… perhaps just under the “Network Admin” tab.
2. Plugin authors allow their code to move out of mu-plugins into the regular plugins directory and then be activated network/site-wide.

This second path seems to be what the Unfiltered Mu folks now allow, per the installation page, which is probably what I’ll end up doing with this plugin in the long-term. This allows it to make use of the standard upgrade notification while also allowing it to be activated across the entire network of sites.

We’ll see what direction the WordPress community goes… in the meantime, if you ever installed “Unfiltered Mu” in the past… you probably want to see about upgrading if you haven’t already

Related posts:

1. Adding the “Unfiltered MU” plugin to WordPress MU to allow all embeds
2. planetOzh: massive review of 43 WordPress plugins (for WordPress Plugin Competition 2009)
3. The challenge of embedding XML into a WordPress MU blog entry
4. Editorial Calendar – a great WordPress plugin to help you plan out your content
5. Successful upgrade to WPMU 1.5.1 – with some lessons learned