multisite

I had a fun afternoon a few months back when all the imagecache images broke on a site I'd just taken live. I've just figured it out, so I'm telling you about it.

This was the situation:

• subsite.client.com was where I was developing the site, one of a family of multisites.
• subsite.com was a parked domain that went to just this site. It was this I'd just pointed to the IP of the box and that wasn't showing any images.

On the development domain, all worked fine. On the subsite domain, nothing.

The problem is that if you go to admin/settings/file-system you get a different thing depending on the domain! Each time, you get 'sites/CURRENT_DOMAIN/files', and the reason is this function:

So if the files directory has not been explicitly set and you're just relying on defaults, you're getting the wrong one.

I don't follow the internal workings of the file system or imagecache (or even symlinks which I consider dark magic on the commandline) to know if this breaking of imagecache is a bug or not.

But at least this is a ten-second fix on future sites. You'll find me here reading this post when I next have to set one up.

I've been putting off setting up multisite on my localhost for ages, mostly because in the past I've found getting Apache virtual hosts to work can be a bit tricky: not impossible, but the sort of thing where I could easily lose an hour on a minor thing I've forgotten to do. And after all, with a shiny new iMac and a hard drive whose proportions I can't even remember, why not just 'drush dl' all over again?

But I'm actually working on a multisite project at the moment, and suddenly getting this to work becomes more interesting than having another SVN copy of my code kicking around.

Given multisite can respond to subfolders, I was wondering if this could work when Drupal itself is in a subfolder, like this:

Turns out it can. Suppose you want a new subsite called 'drupal-subsite'. Here's what to do in your webroot:

Your lolcathost(*) sees just another subfolder that's a site; the symbolic link sends you to the existing Drupal folder; and finally, the multisite system sees that you're browsing 'localhost/drupal-subsite' and selects the localhost.drupal-subsite folder as the one holding your site.

You can also have your subsite explicitly sit below the main site like this:

In which case your sites folder is localhost.drupal-multisite.drupal-subsite and the symlink should be inside the multisite folder:

So when I next get a moment I'll consolidate the various test sites I have, and when I have more than one patch on the go that I want to keep segregated, I can just add a multisite, get a fresh CVS copy of the code, and get going.

I've added details to the documentation too.

(*) yes, I keep typing it like that.