gistfile1.rb

# multi instance stuff
if @node[:postfix_multi]  
    # loop over all multi instances and asemble templates.
    postconf = Hash.new

    @node[:postfix_multi].each do |instance, settings|  
        # convert postfix config into hash to merge into 
        # mult-instance config 
        h = Hash.new
        @node[:postfix].each do |k,v|
            h[k] = v
        end
        postconf = h.merge(settings)
        h.clear

        template "/etc/#{instance}/main.cf" do
            source "main.cf.fm.erb"
            notifies :reload, resources(:service => "postfix")
            # so much pain here.. need to pass in an array. may as well sort it.
            #  could also use .to_a  to flatten this.
            variables(:postconf => postconf.sort)
        end
        postconf.clear
    end
end

gistfile2.txt

<% @postconf.each do |k, v| -%>
<%= k %>=<%= v %>
<% end -%>