only one can rule the world

upstreams.conf.erb

#cartmans
upstream wo {
    <%- @wo.each do |host| %>
    server <%= host %>:80<%- if @wo.length > 1 and @wo.index(host) != 0 %> backup<%- end %>;
    <%- end %>
}
#cartmans2
upstream wo2 { 
    <%- @wo.each do |host| %>
    server <%= host %>:80<%- if @wo.length > 1 and @wo.index(host).modulo(2) != 1 %> backup<%- end %>;
    <%- end %>
}