Protecting the content of public/ in a Rails app

I'm maintaining a Rails app that has content in the public/ folder that will now need to be protected by a login. We're considering moving those folders of files into a path outside of public/ and writing a Rails controller to serve up 开发者_开发百科the content.

Before we begin writing this, I was curious if anyone else has ran into this sort of problem? I looked for some gems / plugins that might already do this but didn't find anything. Has anyone created a gem for this?

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I've done this on a site where people pay to download certain files, and the files are stored in RAILS_ROOT/private. The first thing to know is that you want the web server to handle sending the file, otherwise your app will be held up transmitting large files and this will quickly bring your site to a halt if you have any kind of download volume. So, if you need to check authorization in a controller, then you also need a way to pass control of the download back to the web server. The best way of doing this (that I know of) is the X-Sendfile header, which is supported by Nginx, Apache (with module), and others. With X-Sendfile configured, when your web server receives a X-Sendfile header from your app, it takes over sending the file to the client.

Once you have X-Sendfile working for your web server, a private controller method like this is helpful:

##
# Send a protected file using the web server (via the x-sendfile header).
# Takes the absolute file system path to the file and, optionally, a MIME type.
#
def send_file(filepath, options = {})
  options[:content_type] ||= "application/force-download"
  response.headers['Content-Type'] = options[:content_type]
  response.headers['Content-Disposition'] = "attachment; filename=\"#{File.basename(filepath)}\""
  response.headers['X-Sendfile'] = filepath
  response.headers['Content-length'] = File.size(filepath)
  render :nothing => true
end

Then your controller action could look something like this:

##
# Private file download: check permission first.
#
def download
  product = Product.find_by_filename!(params[:filename])
  if current_user.has_bought?(product) or current_user.is_superuser?
    if File.exist?(path = product.filepath)
      send_file path, :content_type => "application/pdf"
    else
      not_found
    end
  else
    not_authorized
  end
end

Obviously your authorization method will vary and you'll need to change the headers if you're offering files other than PDFs or you want the file to be viewed in the browser (get rid of application/force-download content type).

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You could use Amazon S3. You could use the controllers to generate and serve up the urls behind your secure area, and it also has a feature that basically makes resources available only for a certain amount of time once a url is generated.

Check out this url: http://docs.amazonwebservices.com/AmazonS3/2006-03-01/index.html?RESTAuthentication.html

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AFAIK, X-SendFile is not supported by nginx. Nginx has its own extension allowing this, called X-Accel-Redirect.

You will find more information about this here : https://www.nginx.com/resources/wiki/start/topics/examples/xsendfile/

There is also a rails plugin implementig this feature, on github: goncalossilva/X-Accel-Redirect

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If you want to tie content delivery with your Rails authentication and authorization system, then you essentially have to put the content behind a controller.

If you are looking at a more simple login approach, you can handle it with HTTP Auth and settings in your hosting environment (using htaccess, for example).

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Making the file available at an unpredictable URL is a simple solution currently used in some production systems.

E.g.: GitLab. The following image was uploaded to an issue of a private repository, https://gitlab.com/cirosantilli/test-private/issues/1, but you can still see it:

Note the unguessable 90574279de prefix automatically added to the URL.

Bitbucket (non-Rails) also uses this technique.