Apache mod_headers custom header

You need to use the

ExpiresActive On

directive wherever you want to apply Expires headers, for example

<Location / >    
   ExpiresActive On
   ExpiresByType image/png "access plus 7 days"    
   ExpiresByType image/jpg "access plus 7 days"    
   ExpiresByType image/gif "access plus 7 days"

   ExpiresByType text/html "modification plus 5 days"

   <FilesMatch "\.(gif|jpe?g|png)$">        
      Header set Cache-Control "public"    
   </FilesMatch>

   <FilesMatch "\.(html)$">        
      Header set Cache-Control "public"    
   </FilesMatch>

   <FilesMatch "\.(php)$">
      Header set Cache-Control "private"    
   </FilesMatch> 
</Location>

From the mod_headers docs:

The directives provided by mod_headers can occur almost anywhere within the server configuration. They are valid in the main server config and virtual host sections, inside , and sections, and within .htaccess files.

If you want this to apply to the whole vhost, why put it inside <Location> tags? Just put the directives inside the main vhost config.

<VirtualHost *:80>

  ServerAdmin webmaster@example.com
  ServerName  example.com
  ServerAlias www.example.com

  DocumentRoot /home/deploy/public_html/railsapp/current/public

  LogLevel warn
  ErrorLog /home/deploy/public_html/railsapp/shared/log/error.log
  CustomLog /home/deploy/public_html/railsapp/shared/log/access.log combined

  <IfModule mod_headers.c>
    Header unset X-Runtime
    Header unset X-Powered-By
  </IfModule>

</VirtualHost>

I haven't tested this so apologies in advance if it's incorrect.