===== Redirect http to https apache =====
Tested on Debian.

Modify /etc/apache2/sites-enabled/000-default.conf:
<code>
        RewriteEngine On
        RewriteCond %{HTTPS} off
        RewriteRule (.*) https://%{SERVER_NAME}/$1 [R,L]
        #ServerAdmin webmaster@localhost
        #DocumentRoot /var/www/html
</code>

==== References ====
  * https://www.sslshopper.com/apache-redirect-http-to-https.html