.htaccess redirect http to https

Update 2016

As this answer receives some attention, I want to hint to a more recommended way on doing this using Virtual Hosts: Apache: Redirect SSL

<VirtualHost *:80>
   ServerName mysite.example.com
   Redirect permanent / https://mysite.example.com/
</VirtualHost>

<VirtualHost _default_:443>
   ServerName mysite.example.com
   DocumentRoot /usr/local/apache2/htdocs
   SSLEngine On
# etc...
</VirtualHost>

Old answer, hacky thing given that your ssl-port is not set to 80, this will work:

RewriteEngine on

# force ssl
RewriteCond     %{SERVER_PORT} ^80$
RewriteRule     ^(.*)$ https://%{SERVER_NAME}%{REQUEST_URI} [L,R]

Note that this should be your first rewrite rule.

Edit: This code does the following. The RewriteCond(ition) checks wether the ServerPort of the request is 80 (which is the default http-port, if you specified another port, you would have to adjust the condition to it). If so, we match the whole url (.*) and redirect it to a https-url. %{SERVER_NAME} may be replaced with a specific url, but this way you don't have to alter the code for other projects. %{REQUEST_URI} is the portion of the url after the TLD (top-level-domain), so you will be redirected to where you came from, but as https.

I force the https with following code:

RewriteEngine on
RewriteCond %{HTTPS} off
RewriteRule ^(.*)$ https://%{HTTP_HOST}/$1 [R=301,L]

I use the following to successfully redirect all pages of my domain from http to https:

RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

Note this will redirect using the 301 'permanently moved' redirect, which will help transfer your SEO rankings.

To redirect using the 302 'temporarily moved' change [R=302,L]

This is the best for www and for HTTPS, for proxy and no proxy users.

RewriteEngine On

### WWW & HTTPS

# ensure www.
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^ https://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

# ensure https
RewriteCond %{HTTP:X-Forwarded-Proto} !https
RewriteCond %{HTTPS} off
RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

### WWW & HTTPS