Don't think of doing this kind of thing on a live box

local-development.conf

set $site $host;

# Strip www. prefix
if ($site ~ "^(w{3}\.)?(.*)$") {
  set $site $2;
}

# Strip TLD prefix
if ($site ~ "^(.*)(\.[a-z]{3})$") {
  set $site $1;
}

# Set webroot based on the domain name i.e. $site is `example` for the domain `www.example.dev`
set $webroot /var/www/$site/public;

# Webroot for this domain could not be found 
if (!-d $webroot) {
   set $webroot /var/www/default;
}

root $webroot;