Force www subdomain in lighttpd and preserve path

Question

I would like to setup my lighttpd powered website to redirect users to the www subdomain when browsing the site without the subdomain. I would also like it to preserve the trailing URL and serve the redirect as a permanent 301 redirect. What sort of rules would I need to throw into my lighttpd.conf file?

example.com -> www.example.com
example.com/pagename -> www.example.com/pagename

Answer 1

This will redirect all requests on example.com to www.example.com while preserving the original path:

$HTTP["host"] =~ "^example\.com$" {
  url.redirect = ( "^/(.*)" => "http://www.example.com/$1" )
}