multisite environment à la doodlekit.com

multisite_before_filter.rb

# How-to set up a multi-site environment like the one in doodlekit.com
# every top-level object has a site_id
# The sites table holds all the information for each site, including the name, and what I call a 'handle'.
# The handle is used for many things, but mainly for the sub-domain.
# There is a separate field for the domain # name, so that we can support both the sub-domain, and a custom domain name at the same time.  
# For every request a before_filter runs which looks something like this:

def load_site
  if request.domain == DOODLEKIT_DOMAIN
    sub_domain = request.subdomains.last || 'default'
    @site = Site.find_by_handle(sub_domain)
  else
    @site = Site.find_by_domain(request.domain)
  end
  if @site.nil?
    @site = Site.find_default
  end
  if session[:current_user] &&
      session[:current_user].site_id != @site.id &&
      !session[:current_user].is_system
    session[:current_user] = nil
  end
end

# Basically if the root domain name is 'doodlekit.com', then it takes the last sub-domain element and looks up that handle.
# Otherwise it looks it up by the domain name.  If both of these fail, then just use the default site.
# The @site instance variable is then used to pull up features, menus, pages, layouts, etc. 
# Whenever I decide to implement object caching, the Site object will definitely be the first to go in there.   
# As far as DNS, all I have to do is setup everything as a CNAME to doodlekit.com. There's no Apache config or anything.