Extract the nginx config for discourse to a recipe

Get the upstream servers automatically from Chef nodes

site-cookbooks/kosmos_discourse/templates/nginx_conf.erb

@@ -1,6 +1,8 @@
 # Generated by Chef
 upstream _discourse {
-  server   localhost:<%= @upstream_port %>;
+  <% @upstream_ip_addresses.each do |upstream_ip_address| -%>
+  server   <%= upstream_ip_address %>:<%= @upstream_port %>;
+  <% end -%>
 }
 
 <% if File.exist?(@ssl_cert) && File.exist?(@ssl_key) -%>