To redirect http requests to https on your Apache web server use .htaccess and add the following rewrite rules.
RewriteEngine On
RewriteCond %{SERVER_PORT} ^80$
RewriteRule ^(.*) https://%{SERVER_NAME}/$1 [R,L]
You can also add it inside the virtual host entry of the domain for which you need this redirect.
Tags: apache, mod_rewrite, redirect, URL redirect