Generic way to force https and redirect to naked domain

.htaccess

RewriteEngine On

# Remove www (do it first in case https is not supported by subdomain)
RewriteCond %{HTTP_HOST} ^www.(.+)$ [NC]
RewriteRule ^(.*)$ https://%1/$1 [R=301,L]

# Force https...
# ... if not local
RewriteCond %{SERVER_NAME} !=127.0.0.1
RewriteCond %{SERVER_NAME} !=localhost
# ... and not activated
RewriteCond %{HTTPS} !=on
# ... and proxy (on Heroku, for instance)
#RewriteCond %{HTTP:X-Forwarded-Proto} .
#RewriteCond %{HTTP:X-Forwarded-Proto} !https
# ... Redirect:
RewriteRule ^/?(.*) https://%{SERVER_NAME}/$1 [R,L]