Question

Is it possible to modify the HEADER in Rails 3 when someone requests an image? For example:

http://localhost:3000/assets/myimg.png

I want to add Access-Control-Allow-Origin: “*” to the headers so I can download image files remotely via JavaScript.

UPDATE 1

I have the answer for images under the assets folder to change the headers, but now I also need to do the same thing for public images. I tried the same method below, but no luck.

Example url would be

http://localhost:3000/images/stuff.png

I tried the Rack MiddleWare, but it doesn’t run the call method when going to a public image. I also tried LocationMatch (on a production environment), same no luck.

What do I try for the public images end to change Headers?

UPDATE 2

So, I did manage to get it working via LocationMatch, but the images can not cache. Is there a way to disable image caching via apache?

Answer 1

Assets will be “compiled” and served directly by the web server (Nginx/Apache) so Rails will not serve it in production. You will need to modify the configuration of your web server to add headers.

Something like this in Apache.

<LocationMatch "^/assets/.*$">
  Header add Access-Control-Allow-Origin "*"
  ...
</LocationMatch>

And this in Nginx.

location ~ ^/assets/ {
  add_header Access-Control-Allow-Origin *;
  ...
}

See this guide for further details on precompiling assets.

Update: If you need to apply headers in the development environment you can do so with some custom rack middleware. See this gist for an example.