matthewwhitworth.com

• Published:February 6th, 2008
• Comments:No Comments
• Category:Diary, Meta, Tech

I’ve spent the last few days investigating Plone as a potential replacement for WordPress for the okcomputer.org web site, but, as is frequently the case when experimenting with new technology around here, I’ve been beating my head against the wall trying to get my Plone installation to work behind an Apache proxy. I could successfully pull up the main page’s content in my browser, but none of the Cascading Style Sheets or Javascript files were making it. The result was less than inspiring. So while I was waiting for the tornadoes to pass through tonight, I fired up my browser, tailed my log files and started beating on it.

First off, the mod_rewrite rule from the RewriteRuleWitch wasn’t matching. Fantastic. Here’s what it gave me:

RewriteRule ^($|/.*) \
http://127.0.0.1:8080/VirtualHostBase/\
http/%{SERVER_NAME}:80/okcomputer/VirtualHostRoot$1 [L,P]

The root document was matching, but nothing else was. After setting my RewriteLogLevel to 9, I saw that the URI as it was being tested against the regex didn’t begin with a /. So I removed the slash from the regex and added one to the substitution pattern:

RewriteRule ^($|.*) \
http://127.0.0.1:8080/VirtualHostBase/\
http/%{SERVER_NAME}:80/okcomputer/VirtualHostRoot/$1 [L,P]

Now the RewriteRule was matching, but the proxied requests were generating 400 errors on the Zope HTTP server. The obvious culprits were the spaces in some of the URL’s, specifically in URL’s containing the string “Plone Default”. My browser was (correctly) escaping the spaces as “%20”, but by the time mod_rewrite had processed the request and passed it on to mod_proxy the spaces were back resulting in a malformed HTTP request.

I found the fix for this last bit at Velo World. The trick is to define a RewriteMap and then use mod_rewrite’s built in escape function, like so:

RewriteMap escape int:escape
...
RewriteEngine On
RewriteRule ^($|.*) \
http://127.0.0.1:8081/VirtualHostBase/\
http/%{SERVER_NAME}:80/okcomputer/VirtualHostRoot/${escape:$1} [L,P]

And success! But what a pain in the ass! I’d love to blame mod_rewrite, but I’m sure there’s some valid reason it doesn’t re-escape substitutions by default. Instead I’ll blame Plone. Why? Why do you put spaces in your %$#@! URL’s. And given the number of pages on the web explaining how to set up Plone behind an Apache server with mod_rewrite and mod_proxy — including Plone’s own documentation — how come none of them mentioned this? Very frustrated, but the problem is fixed, the tornadoes have passed, it’s going on 2:00 AM, I’m going to bed.

UPDATE 2/14/2008: Special thanks to Sascha, who’s been helping me debug my RewriteRule issue.  The Witch’s rule should work, I just can’t figure out why apache is stripping that slash of the front of my URI’s.  I’m not using a RewriteBase, and the RewriteRule isn’t an a .htaccess file, so I just have no idea what the problem is.