I use this, which works for me:
# cat /etc/lighttpd/conf.d/https-redirect.conf
$HTTP["scheme"] == "http" {
# capture vhost name with regex conditiona -> %0 in redirect pattern
# must be the most inner block to the redirect rule
$HTTP["host"] =~ ".*" {
url.redirect = (".*" => "https://%0$0")
}
}