This may be an Nginx wrinkle, or it may be because I don't understand Unix permissions.
We're using Hudson CI to deploy our staging instance. So RAILS_ROOT is /var/lib/hudson/jobs/JOBNAME/workspace.
Hudson runs as hudson user
Nginx runs as www-data user
hudson and nginx are both members of the www group
root of my nginx conf points to RAILS_ROOT/public as per normal.
RAILS_ROOT/config/environment.rb is owned by www-data (so Passenger runs as www-data)
RAILS_ROOT and everything in it is owned by the www group and group has r/w/x permissions
As it stood, Nginx threw 403 permission denied when requesting any url. error.log contained entries like this: public/index.html" is forbidden (13: Permission denied).
These did not fix the or change the error (each with a stop/start of Ngnix):
chmod 777 -R RAILS_ROOT
chgrp www -R /var/lib/hudson
I also tried Nginx as root, and passenger complained that it could not find config/environment (despite the path displayed on the error page being correct).
The fix was to ensure everybody has read permissions on each directory in the heirachy. In this case chmod o+r /var/lib/hudson.
But if the group has read permissions on the directory, and nginx is a member of the owner group of the directory, why was it necessary to allow everyone read permissions? Is there something have not grokked about permissions?
$nginx -V
nginx version: nginx/0.7.61
built by gcc 4.4.1 (Ubuntu 4.4.1-4ubuntu8)
configure arguments: --prefix=/opt/nginx --add-module=/usr/lib/ruby/gems/1.8/gems/passenger-2.2.5/ext/nginx --with-http_ssl_module --with-pcre=~/src/pcre-8.00/ --with-http_stub_status_module
$cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=9.10
DISTRIB_CODENAME=karmic
DISTRIB_DESCRIPTION="Ubuntu 9.10"
