Rails page caching is pretty simple to get working usually. If you’re new to caching in Rails, there’s plenty of good tutorials out there to get you up and running in no time like this one from Rails Envy. Rails is a resource hog and on my servers I’ve got about two dozen apps running. Combined they use up most of my memory and on peek hours can push the server to the brink of disaster so caching is extremely important to keeping things under control. The last thing I feel like doing is having to offload some apps to another server. I’ve used fragment and action caching with great success but wanted to use page caching on a new app I am building. The problem I have been having was that the pages were being cached properly but Apache wasn’t serving them up. I tried a whole slew of different tweaks to my Apache configuration before finally finding the problem. I found the problem by including the following in my Apache configuration:

Using that debug information I was able to toy with the rewrite settings that were suggested by the many tutorials out there and find the problem. Most Rails page caching posts I found that used Apache and mongrel_cluster had a suggested rewrite configuration like this:

Now, this may be specific to my Apache configuration but what I found was that the rules weren’t rewriting to the correct urls. They were missing / and ending up relative. The way I fixed it was pretty trivial but took me some time to discover so I figured I post it. The solution ended up being like this:

I added some preceding /’s and removed the / after cache on the second rule since the $1 got translated with the /. This modified configuration got my page caching working properly.

This entry was posted on Saturday, May 17th, 2008 at 11:14 pm and is filed under Apache, Ruby on Rails. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.