Force SSL to codeigniter 3

.htaccess

RewriteEngine On
RewriteCond %{HTTPS} !=on
RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

<IfModule mod_rewrite.c>
    RewriteEngine on
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteRule ^ index.php [L]
</IfModule>

config.php

$config['base_url'] = 'https://my.domain/';