Require a sub-directory of a website to only be accessible using a https / ssl connection

If for example you want to allow http access to your whole site but require https for /admin/ then use the following either in your httpd.conf or .htaccess file located in the root of the website.

RewriteEngine On

RewriteCond %{SERVER_PORT} 80
RewriteCond %{REQUEST_URI} admin
RewriteRule ^(.*)$ https://www.example.com$1 [R,L]