default.rb

hosts = Hash.new

search(:node, "*") do |server|
  hosts[server[:ipaddress]] << server[:hostname]
end

template "/tmp/hosts" do
  source "hosts.erb"
  mode 0644
  owner "root"
  group "root"
  variables(
            :hostname => node[:hostname],
            :ipaddress => node[:ipaddress],
            :hosts => hosts
            )
end

hosts.erb

127.0.0.1       localhost
<%= @ipaddress %>       <%= "#{@hostname}.local #{@hostname}" %>

# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts

<% @hosts.each do |ip,host| %>
<%= "#{ip} #{host}" %>
<% end %>