gistfile1.rb

["cert1", "cert2"].each do |cert| 
  cookbook_file "#{node[:nginx][:dir]}/ssl/#{cert}" do
    owner node[:nginx][:user]
    mode "0600"
    source "ssl/#{cert}"
    notifies :run, "execute[add chain certificate #{cert}]"
    notifies :restart, "service[nginx]"
  end

  execute "add chain certificate #{cert}" do
    action :nothing
    command "cat #{node[:nginx][:dir]}/ssl/#{cert} #{chain_cert} > #{node[:nginx][:dir]}/ssl/composite-#{cert}"
  end
end