I want to follow Google's directive in terms of cache headers for images, scripts and styles.
After reading symfony's documentation about http cache, I decided to install FOSHttpCacheBundle. The I set up rules for path like ^/Resources/ or ^/css/. I then fail to see it the proper headers for my images using Chrome's console.
Alternatively, I have read that, since my server is handling the resource, this is not Symfony that deals with this matter (yet I read in the doc that Symfony Proxy was good for shared-hosting servers, which is what I have).
So should I just add lines to my .htaccess as explained in here, or am I simply misusing FOSHttpCacheBundle? (Or both.)
Static files (including javascript files, CSS stylesheets, images, fonts...) are served directly by the web server. As the PHP module is not even loaded for such files, you must configure the server to set proper HTTP headers. You can do it using a .htaccess file if you use Apache but doing it directly in httpd.conf/apache2.conf/vhost conf (depending of your configuration) will be better from a performance point of view.
If you also want want to set HTTP cache headers for dynamic content (HTML generated by Symfony...), then you must use FosHttpCache or any other method provided by Symfonny such as the @Cache annotation.