serving_files_with_nginx.txt

# Assumptions:

* Rails 3.2.x
* nginx
* capistrano deploy
* "X-Accel-Mapping header missing" messages in nginx error.log file
* You want to serve static files with nginx instead of Rails

# nginx configuration:

passenger_set_cgi_param HTTP_X_ACCEL_MAPPING "/home/user/rails_app/shared/files/=/documents/";
passenger_pass_header X-Accel-Redirect;

location ~ ^/documents/(\d\d\d)/(\d\d\d)/(\d\d\d)/(.*)$ {
  alias /home/user/rails_app/shared/files/$1/$2/$3/$4;
  internal;
}

# DocumentsController:
def index
  @document = Document.find(params[:id])
  # @document.path #=> /home/user/releases/20130111141529/files/000/000/001/file.txt
  send_file @document.path.sub(/releases\/\d{14}/, 'shared')
end

# Rails: config/environments/production.rb
config.action_dispatch.x_sendfile_header = 'X-Accel-Redirect'

# Request: 
http://localhost:3000/documents/1

# References:

* http://stackoverflow.com/questions/954470/serving-large-files-through-nginx-via-rails-2-3-using-x-sendfile
* http://airbladesoftware.com/notes/rails-nginx-x-accel-mapping
* http://wiki.nginx.org/HttpCoreModule#alias
* http://greenlegos.wordpress.com/2011/09/12/sending-files-with-nginx-x-accel-redirect/
* http://stackoverflow.com/questions/6237016/message-x-accel-mapping-header-missing-in-nginx-error-log