nginx rewrite rules with Passenger - ruby-on-rails

Question

I'm trying to migrate to nginx from Apache using Passenger in both instances to host a Rails app. The app takes a request, which is for an image- if the image exists at /system/logos/$requestedimage then it should get served, or it should be allowed to hit the Rails app to generate it if needed (where it is then cached to /system/logos).
In Apache I used the following:
RewriteCond %{DOCUMENT_ROOT}/system/logos/%{REQUEST_FILENAME} -f
RewriteRule ^/(.*)$ http://assets.clg.eve-metrics.com/system/logos/$1
This worked fine. The assets. subdomain is another subdomain but with the same root, just Passenger disabled, specifically set up for hosting static files (expires-wise).
In nginx I am using the following:
server {
listen 80;
passenger_enabled on;
server_name clg.eve-metrics.com www.clg.eve-metrics.com;
root /opt/www/clg/current/public;
gzip on;
gzip_min_length 1000;
gzip_proxied expired no-cache no-store private auth;
gzip_types text/plain application/xml text/css application/javascript;
gzip_disable msie6;
error_page 500 502 503 504 /50x.html;
location = /50x.html {
}
if (-f $document_root/system/logos$request_filename) {
rewrite ^/(.*)$ http://assets.clg.eve-metrics.com/system/logos/$1 break;
}
}
This doesn't work so well. At all, in fact. It never redirects to the cached path and it never hits the Rails app. It's like nginx is assuming it's a static asset so not passing it on to Passenger. Is there a way to stop this behaviour so it hits the app?

Answer 1

My rails application is running on nginx and passenger. I have moved my rails cache directory from the default /public to /public/system/cache/. To make it work, I had to insert this into my vhost config file:
if (-f $document_root/system/cache/$uri/index.html) {
rewrite (.*) /system/cache/$1/index.html break;
}
if (-f $document_root/system/cache/$uri.html) {
rewrite (.*) /system/cache/$1.html break;
}
I remember that I too tried to make it work with $request_filename, but didn't get it to work. Try with $uri instead and see if it works :-)

Answer 2

James, please try this configuration file
https://gist.github.com/711913
and pay attention on this location config:
location ~* \.(png|gif|jpg|jpeg|css|js|swf|ico)(\?[0-9]+)?$ {
access_log off;
expires max;
add_header Cache-Control public;
}
passenger won't let Rails to manage your assets files if you have right permissions (user run nginx should has permissions to access to file directly)